Backend computer with SLC4.4 Linux did'not work as mserver because some security
protection under iptables service (could not connect with frontend computers).
The connection established if to make ( under root ) iptables disable
by command: service iptables stop, or much more gently
just to accept mserver port with command (under root):
iptables -I INPUT -p tcp --dport 1175 -j ACCEPT
( in /etc/service 
  midas    1175/tcp       #Midas server)
To check which ports is open
it is possible to use the command: "netstat -n" to see digital numbers of ports.

Hi All,

I'm testing MIDAS SVN rev-4113 on Scientific Linux 5.1 (i386) and the Analyzer 
can't start as Daemon. What I mean "can't" is that it stops running 
immediately without leaving any error messages. However, it can run offline or 
without becoming a Daemon. I have tested with ROOT 5.14e/5.16/5.18 and 
the "Experiment" example coming with MIDAS and this problem always happens. 
Any ideas?

Best Regards,
Jimmy

A major change was made to mhttpd, changing all internal URLs to relative paths.
This allows proxy access to mhttpd via an apache server for example, which might
be needed to securely access an experiment from outside the lab through a
firewall. Following setting can be places into the Apache configuration,
assuming the experiment runs on machine "online1.your.domain", and apache on a
publically available machine "www.your.domain":

Redirect permanent /online1 http://www.your.domain/online1
ProxyPass /online1/ http://online1.your.domain/

<Location "/online1">
  AuthType Basic
  AuthName ...
  AuthUserFile ...
  Require user ...
</Location>

If the the URL http://www.your.domain/online1 is accessed, it gets redirected
(after optional authentication) to http://online1.your.domain. If you click on
the mhttpd history page for example, mhttpd would normally redirect this to 

http://online1.your.domain/HS/

but this is not correct since you want to go through the proxy www.your.domain.
The new relative redirection inside mhttpd now redirects the history page
correctly to

http://www.your.domain/onlin1/HS/

I had to change many places inside mhttpd to make this work, and I'm not 100%
sure if I covered all occurrences. So if you upgrade to mhttpd revision 4115 and
observe some error accessing some pages, please report it to me.

- Stefan

> A major change was made to mhttpd, changing all internal URLs to relative paths.
> This allows proxy access to mhttpd via an apache server for example, which might
> be needed to securely access an experiment from outside the lab through a
> firewall.

It is good to see improvements to the MIDAS URLs. We have been successfully running
mhttpd behind an apache SSL/HTTPS proxy without these changes, but our case was very
limited to one experiment, one mhttpd behind one proxy. I hope to test these changes
in the near future at CERN, I guess we will hear if things broke. I am especialloy
worried about the function for "split mhttpd history generator" via "/History/URL".
I remember it was hard to get it right and I hope if this function did not survive
this update, it will be easy to resurrect.
K.O.

I'm using midas to read data from a waveform digitizer at event rates of
10-30kHz. To accomplish this the digitizer is read via Block transfers and the
raw data put into a single MIDAS event.  Thus a MIDAS event could contain upto
250 physical events and at maximum 350kBytes.  In the analyzer modules I had
been analyzing the first physics event contained in a MIDAS event with no
problem.  Recently I tried to analyze all the physical events.  At low rates,
100hz-1khz, this was no problem, 1-5 physical events in a MIDAS event.  At
higher rates 10-20kHz, where there are about 40physical events per MIDAS event,
 the analyzer keeps up for a  few seconds then seg faults with " 'shared object
read from target memory' has disappear; keeping it symbols".  Any suggestions as
to why the analyzer is crashing would be very helpful.

Thanks,

Robert     

> I'm using midas to read data from a waveform digitizer at event rates of
> 10-30kHz. To accomplish this the digitizer is read via Block transfers and the
> raw data put into a single MIDAS event.  Thus a MIDAS event could contain upto
> 250 physical events and at maximum 350kBytes.  In the analyzer modules I had
> been analyzing the first physics event contained in a MIDAS event with no
> problem.  Recently I tried to analyze all the physical events.  At low rates,
> 100hz-1khz, this was no problem, 1-5 physical events in a MIDAS event.  At
> higher rates 10-20kHz, where there are about 40physical events per MIDAS event,
>  the analyzer keeps up for a  few seconds then seg faults with " 'shared object
> read from target memory' has disappear; keeping it symbols".  Any suggestions as
> to why the analyzer is crashing would be very helpful.

I personally have never seen this error message. The analyzer is designed such that
it produces "back pressure" if the data rate is higher than the analysis rate and
you have "request all events" on. The only thing I can image are the following two
issues:

- At higher rate where you have more than 40 physical events per MIDAS event, there
is some bug in your analysis code which gets exploited only in that case. Maybe some
temporary array which is only 35 entries long or something like this.

- The back pressure mentioned above will slow down the frontend. If your computer
busy logic is not working correctly, you might get more triggers than you can
acquire. Maybe then the data gets screwed up and the analyzer chokes on it.

Finding the exact reason is not simple. For sure you have to run the analyzer inside
the debugger, to see exactly where the segfault happens. You then maybe have to
produce some dummy data in the frontend (like always sending the same event) to
disentangle some possible trigger problems from other problems.

Best regards,

  Stefan

In revision 4090 I implemented ODB links to individual array elements. Now you
can have for example:

Key name                        Type    #Val  Size  Last Opn Mode Value
---------------------------------------------------------------------------
array                           INT     10    4     2m   0   RWD
                                        [0]             0
                                        [1]             0
                                        [2]             123
                                        [3]             0
                                        [4]             0
                                        [5]             0
                                        [6]             0
                                        [7]             0
                                        [8]             0
                                        [9]             0
element2 -> /array[2]           INT     1     4     3m   0   RWD  123

In this case, the link "element2" points to the third element of "array", but is
treated like a single value. This links are very useful for example for the
"Edit on start" parameters, which can now point to individual array elements.
The same is true for the "Links BOR" when the logger writes to a MySQL database.

This modification required major modifications in the ODB. I have carefully
tested the example experiment from the distribution to verify that everything is
fine, but I'm not 100% sure that I covered all possible situations. So if you
update to revision 4090+ and you observe some strange behavior related to links
in the ODB, please report.

There are following two new functions related to this change: 

  db_get_link()
  db_get_link_data()

They are counterparts of db_get_key() and db_get_data(), respectively, but
without following links in the ODB. These functions are probably not of much use
outside odbedit and mhttpd, which are supposed to display links explicitly. Most
user applications want to follow links without even knowing that these are links.

Hi,
   has anyone managed to get midas to work on a x86_64 processor. I followed the
instructions for the 64-bit opteron but i am getting runtime error when trying
the examples.

 When running example/basic/odb_test I getting errors like

[odb.c:6818:db_get_record] struct size mismatch for "/Alarms/Alarms/Demo ODB"
(464 instead of 452)
[odb.c:6818:db_get_record] struct size mismatch for "/Alarms/Alarms/Demo ODB"
(464 instead of 452)
[midas.c:16576:al_check] Cannot get alarm record

Any ideas what is wrong?

>    has anyone managed to get midas to work on a x86_64 processor. I followed the
> instructions for the 64-bit opteron but i am getting runtime error when trying
> the examples.


We run 64-bit MIDAS on RHEL4 with 64-bit ROOT and everything generally works,
except for compatibility problems with 32-bit MIDAS.

Everything should work if you ensure that on your 64-bit machine everything is
compiled 64-bit (including the mserver - we always forget to install the correct version
to /usr/local/bin). 32-bit MIDAS programs running on other machine
can talk to 64-bit MIDAS via the mserver.

The big problem is that 64-bit and 32-bit ODB turned out to be incompatible - several data
fields have different sizes - and we did not decide yet how to fix this. Any fix will involve
breaking the binary ODB for one of the two platforms (we could break both, just to be fair, heh!)

>  When running example/basic/odb_test I getting errors like
> [odb.c:6818:db_get_record] struct size mismatch for "/Alarms/Alarms/Demo ODB" (464 instead of 452)

Yes, data size mismatch errors indicates that you mixed 32-bit and 64-bit MIDAS. Recompile everyting
as 64-bit, remove all the dot-ODB files, remove all the shared memory segments (ipcrm),
then everything should work.

K.O.

> We run 64-bit MIDAS on RHEL4 with 64-bit ROOT and everything generally works,
> except for compatibility problems with 32-bit MIDAS.
> 
> The big problem is that 64-bit and 32-bit ODB turned out to be incompatible ...

I have now identified 3 data structures that change size when compiled with "-m64":

EVENT_REQUEST: stores a pointer to a function. Pointer size is 4 bytes with -m32 and 8 bytes with -m64.
This structure is part of an array inside BUFFER_HEADER, resulting in a sizable size mismatch between 32
bit and 64 bit shared memory data buffers.

The fix is simple: the function pointer is not used anywhere. Replace is with a "DWORD unused_filler"
makes -m32 and -m64 data buffers compatible. (But breaks compatibility with previous -m64 compiled midas).

CHN_SETTINGS and CHN_STATISTICS: apparently, -m32 and -m64 GCC has different packing rules and in -m64
mode, 4 bytes of padding are added to these data structures. Size size mismatch appears to be benign,
but will result in "size mismatch" complaints from ODB.

The fix is simple: adding "__attribute__ ((__packed__))" to the definition of the data structure makes
-m64 identical to -m32.

The "svn diff" of changes involved is attached below.

The biggest problem here is that making 32-bit ODB and 64-bit ODB compatible requires breaking one or
the other (My proposed changes break the 64-bit version. Alternatively, one could add explicit padding
to these data structures and break the 32-bit ODB).

I think it is important to make 32-bit and 64-bit code compatible: at TRIUMF we have to use a mixed
environment because out latest host computers all run 64-bit Linux while all our VME processors and all
older machines can only run 32-bit code; this incompatibility causes us weekly headaches.

Any thoughts?

K.O.

(this output of svn diff is doctored for clarity)

ladd00:midas$ svn diff
Index: include/midas.h
===================================================================
--- include/midas.h     (revision 3744)
+++ include/midas.h     (working copy)
-   void (*dispatch) (HNDLE, HNDLE, EVENT_HEADER *, void *);
+   INT unused; // was void (*dispatch) (HNDLE, HNDLE, EVENT_HEADER *, void *);
 } EVENT_REQUEST;
 
--- include/msystem.h   (revision 3744)
+++ include/msystem.h   (working copy)

+#define PACKED __attribute__ ((__packed__))  <--- this goes into midas.h inside the #ifdef "we use GCC"
 
-typedef struct {
+typedef struct PACKED { ... CHN_SETTINGS
 
-typedef struct {
+typedef struct PACKED { ... CHN_STATISTICS

> The biggest problem here is that making 32-bit ODB and 64-bit ODB compatible requires breaking one or
> the other (My proposed changes break the 64-bit version. Alternatively, one could add explicit padding
> to these data structures and break the 32-bit ODB).
> 
> I think it is important to make 32-bit and 64-bit code compatible: at TRIUMF we have to use a mixed
> environment because out latest host computers all run 64-bit Linux while all our VME processors and all
> older machines can only run 32-bit code; this incompatibility causes us weekly headaches.
> 
> Any thoughts?

I agree to make 32-bit and 64-bit compatible. In the long run, everything will be 64-bit, so I would suggest
in breaking the 32-bit ODB, add some padding there where needed, probably with some conditional compiling.
This ensures to keep the native 64-bit packing, which probably will be somehow optimized for 64-bit
architectures and therefore might be a bit faster in the long run, when most systems are 64-bit. After this
has been implemented and well tested, I would go with an official announcement of the 32-bit break in the ODB,
and release a new version, so people can update from a TAR file if necessary. Existing ODB's can be converted
to the new format by exporting them in XML form and importing them again after the upgrade.

> I agree to make 32-bit and 64-bit compatible. In the long run, everything will be 64-bit, so I would suggest
> in breaking the 32-bit ODB, add some padding there where needed, probably with some conditional compiling.

I now have the patches to implement this. Changes turned out to be minimal:

1) midas.h: remove unused field "dispatch" from EVENT_REQUEST and bump DATABASE_VERSION from 2 to 3
2) msystem.h: add 32-bit padding to CHN_STATISTICS and CHN_SETTINGS

(Pedantic note: the C/C++ languages permit compilers to arbitrary pad data members inside structures and one is
not supposed to rely on the specific layout of "struct"s, they could changing from day to day depending on
compiler vendor, version, 32/64 bit, optimization level, etc. This is quite silly, but I guess it was the only way
"they" could agree on a standard)

In practice, compilers are will behaved and one can follow simple rules and stay out of trouble.
1) if all data members are of the same size -> no padding
2) do not use "double" (64-bit) and "short" (16-bit), make all char[] arrays divisible by 4 -> size of everything
is 32-bit, see rule 1
3) if you have to use "short", they have to come in pairs to keep everything else aligned to 32-bit
4) if you have to use "double" (or uint64_t), keep them aligned to 64-bit, i.e. struct { int a,b,c; double x;} is
*bad* (4-byte padding may be added between c and x). struct { int a,b,c,d; double x; } is good.

Below are is "svn diff include/midas.h include/msystem.h". These changes have been tested on SL4 32-bit and
64-bit, SL5 32/64, F7 32/64 and SL4/ICC (Intel compiler) 32 bit and 64 bit.

The testing was done by adding checks on sizes of all struct's kept on ODB, i.e.
   assert(sizeof(CHN_SETTINGS        ) ==    640); // ODB v3 with padding
   assert(sizeof(CHN_STATISTICS      ) ==     32); // ODB v3 with padding
   ... etc ...

K.O.

ladd03:midas$ svn diff include/midas.h include/msystem.h
Index: include/midas.h
===================================================================
--- include/midas.h     (revision 3798)
+++ include/midas.h     (working copy)
@@ -38,7 +38,7 @@
  *  @{  */

 /* has to be changed whenever binary ODB format changes */
-#define DATABASE_VERSION 2
+#define DATABASE_VERSION 3

 /* MIDAS version number which will be incremented for every release */
 #define MIDAS_VERSION "2.0.0"
@@ -810,8 +810,6 @@
    short int event_id;           /**< event ID                        */
    short int trigger_mask;       /**< trigger mask                    */
    INT sampling_type;            /**< GET_ALL, GET_SOME, GET_FARM     */
-                                 /**< dispatch function */
-   void (*dispatch) (HNDLE, HNDLE, EVENT_HEADER *, void *);
 } EVENT_REQUEST;

 typedef struct {
Index: include/msystem.h
===================================================================
--- include/msystem.h   (revision 3798)
+++ include/msystem.h   (working copy)
@@ -454,6 +454,7 @@
    INT event_id;
    INT trigger_mask;
    DWORD event_limit;
+   INT pad; // FIXME 64-bit "double" should be 64-bit aligned
    double byte_limit;
    double tape_capacity;
    char subdir_format[32];
@@ -465,6 +466,7 @@
    double bytes_written;
    double bytes_written_total;
    INT files_written;
+   INT pad; // FIXME pad data structure to be 64-bit aligned
 } CHN_STATISTICS;

 typedef struct {
ladd03:midas$

> > I agree to make 32-bit and 64-bit compatible. In the long run, everything will be 64-bit, so I would suggest
> > in breaking the 32-bit ODB, add some padding there where needed, probably with some conditional compiling.
> 
> I now have the patches to implement this. Changes turned out to be minimal:
> 
> 1) midas.h: remove unused field "dispatch" from EVENT_REQUEST and bump DATABASE_VERSION from 2 to 3
> 2) msystem.h: add 32-bit padding to CHN_STATISTICS and CHN_SETTINGS

The padding of CHN_STATISTICS and CHN_SETTINGS is not working right - somehow mhttpd and mlogger keep recreating the
data in ODB and erasing the padding fields. I am looking into this.

K.O.

> > > I agree to make 32-bit and 64-bit compatible. In the long run, everything will be 64-bit, so I would suggest
> > > in breaking the 32-bit ODB, add some padding there where needed, probably with some conditional compiling.
> > 1) midas.h: remove unused field "dispatch" from EVENT_REQUEST and bump DATABASE_VERSION from 2 to 3
> > 2) msystem.h: add 32-bit padding to CHN_STATISTICS and CHN_SETTINGS

I am now trying a different solution of to fixing the issue of CHN_STATISTICS and CHN_SETTINGS changing size.

1) midas.h: (same as before) remove unused field "dispatch" from EVENT_REQUEST and bump DATABASE_VERSION from 2 to 3
2) msystem.h: in CHN_STATISTICS and CHN_SETTINGS change type of "event_limit" and "files_written" from int to "double".

Below are the latest ODBv3 meta patches:

ladd03:midas$ svn diff
Index: include/midas.h
===================================================================
--- include/midas.h     (revision 3844)
+++ include/midas.h     (working copy)
 /* has to be changed whenever binary ODB format changes */
-#define DATABASE_VERSION 2
+#define DATABASE_VERSION 3
.........
    short int trigger_mask;       /**< trigger mask                    */
    INT sampling_type;            /**< GET_ALL, GET_SOME, GET_FARM     */
-                                 /**< dispatch function */
-   void (*dispatch) (HNDLE, HNDLE, EVENT_HEADER *, void *);
 } EVENT_REQUEST;

Index: include/msystem.h
===================================================================
--- include/msystem.h   (revision 3845)
+++ include/msystem.h   (working copy)
-"Event limit = DWORD : 0",\
+"Event limit = DOUBLE : 0",\
..................
-"Files written = INT : 0",\
+"Files written = DOUBLE : 0",\
..................
-   DWORD event_limit;
+   double event_limit;
..................
-   INT files_written;
+   double files_written;

K.O.

These changes to make 32-bit and 64-bit ODB binary compatible with each other are now commited to midas svn, revision 4080.

Starting with this revision, ODB version changes from 2 to 3, breaking binary compatibility with previous releases.

Before upgrading to this revision, save your ODB as an XML file, *and* try to reload it, to catch any potential problems with parsing of the XML file.

Part of this commit are checks for sizes of important midas data structures stored in ODB shared memory - if the compiled size does not match the expected 
value, binary compatibility is broken and the program will abort - to avoid further corruption of ODB shared memory. This feature is only enabled on Linux and 
it is expected to trigger only on compiler malfunctions (generates wrong data size) and on accidental or intentional changes to important data structures in 
midas, to warn the user that they broke ODB binary compatibility.

K.O.

> > > > I agree to make 32-bit and 64-bit compatible. In the long run, everything will be 64-bit, so I would suggest
> > > > in breaking the 32-bit ODB, add some padding there where needed, probably with some conditional compiling.
> > > 1) midas.h: remove unused field "dispatch" from EVENT_REQUEST and bump DATABASE_VERSION from 2 to 3
> > > 2) msystem.h: add 32-bit padding to CHN_STATISTICS and CHN_SETTINGS
> 
> I am now trying a different solution of to fixing the issue of CHN_STATISTICS and CHN_SETTINGS changing size.
> 
> 1) midas.h: (same as before) remove unused field "dispatch" from EVENT_REQUEST and bump DATABASE_VERSION from 2 to 3
> 2) msystem.h: in CHN_STATISTICS and CHN_SETTINGS change type of "event_limit" and "files_written" from int to "double".
> 
> Below are the latest ODBv3 meta patches:
> 
> ladd03:midas$ svn diff
> Index: include/midas.h
> ===================================================================
> --- include/midas.h     (revision 3844)
> +++ include/midas.h     (working copy)
>  /* has to be changed whenever binary ODB format changes */
> -#define DATABASE_VERSION 2
> +#define DATABASE_VERSION 3
> .........
>     short int trigger_mask;       /**< trigger mask                    */
>     INT sampling_type;            /**< GET_ALL, GET_SOME, GET_FARM     */
> -                                 /**< dispatch function */
> -   void (*dispatch) (HNDLE, HNDLE, EVENT_HEADER *, void *);
>  } EVENT_REQUEST;
> 
> Index: include/msystem.h
> ===================================================================
> --- include/msystem.h   (revision 3845)
> +++ include/msystem.h   (working copy)
> -"Event limit = DWORD : 0",\
> +"Event limit = DOUBLE : 0",\
> ..................
> -"Files written = INT : 0",\
> +"Files written = DOUBLE : 0",\
> ..................
> -   DWORD event_limit;
> +   double event_limit;
> ..................
> -   INT files_written;
> +   double files_written;
> 
> K.O.

I upgraded from 1.9.5 to the latest on SVN an it works fine

While working on improvements to the MIDAS history system, I understood the data
format of the MIDAS .hst files and wrote a standalone program to extract data
from them, called mhdump.

mhdump is intended to be easier to use, compared to mhist. By default it reads
and decodes all the data in the given .hst files, with options to limit the
decoding to specified events and tags, and an option to omit the event and tag
names from the output.

mhdump is completely standalone and does not require MIDAS header files and
libraries.

The mhdump source code and a description of the .hst file format are here:
http://daq-plone.triumf.ca/SR/MIDAS/utils/mhdump/

I hope people find this program useful. If you have any feedback (patches, bug
reports, requests for improvements), please post them as replies to this forum
message.

K.O.

> I hope people find this program useful. If you have any feedback (patches, bug
> reports, requests for improvements), please post them as replies to this forum
> message.

I wouldn't mind putting this into the midas distribution. Put it under utils/, add
an entry to the Makefile, and fix that warning:


mhdump.cxx: In function `int readHstFile(FILE*)':
mhdump.cxx:161: warning: comparison between signed and unsigned integer expressions

> > I hope people find this program useful. If you have any feedback (patches, bug
> > reports, requests for improvements), please post them as replies to this forum
> > message.
> 
> I wouldn't mind putting this into the midas distribution. Put it under utils/, add
> an entry to the Makefile, and fix that warning:
> 
> 
> mhdump.cxx: In function `int readHstFile(FILE*)':
> mhdump.cxx:161: warning: comparison between signed and unsigned integer expressions

Done and done.

The program mhdump, a standalone decoder for midas history files, is now in midas svn.

K.O.

Dear MIDAS users,

I want to add several .root-files produced by the MIDAS analyzer, in a fast 
and convenient way. ROOT's hadd fails because it does not know how to treat 
TFolders. I guess this problem is not unique to me, so I hope that somebody of 
you might already have found a solution.

Why don't I just run "analyzer -r 1 10000"?
We have taken lots of runs under (rapidly) varying conditions, so it would be 
lots of "-r". And the analysis is quite involved, so rerunning all data takes 
about one hour on a fast PC making this quite painful.
Therefore, I would like to rerun all data only once, and then add the result 
files depending on different criteria.

Of course, I tried to write a script that does the adding. But somehow it is 
incredibly slow. And I am not the Master Of C++, too.

Is there any deeper reason for MIDAS using TFolders, not TDirectorys? ROOT's 
hadd can treat TDirectory. Can I simply patch "my" MIDAS? Is there general 
interest in a change like this? (Does anyone have experience with the speed of 
hadd?)

Looking forward to comments from the Forum.

Cheers,

Randolf

The following program handles regular directories in a file, or folders (ugh).
Most histograms are added bin by bin.

For scaler events it is convenient to see the counts as a function of time (ala
sclaer history plots in mhttpd).  If the histogram looks like a scaler plot versus
time, then new bins are added on to the end (or into the middle!) of the histogram.

All different versions of cuts are kept.

TTrees are not explicitly supported, so probably don't do the right thing...

John.

> Dear MIDAS users,
> 
> I want to add several .root-files produced by the MIDAS analyzer, in a fast 
> and convenient way. ROOT's hadd fails because it does not know how to treat 
> TFolders. I guess this problem is not unique to me, so I hope that somebody of 
> you might already have found a solution.
> 
> Why don't I just run "analyzer -r 1 10000"?
> We have taken lots of runs under (rapidly) varying conditions, so it would be 
> lots of "-r". And the analysis is quite involved, so rerunning all data takes 
> about one hour on a fast PC making this quite painful.
> Therefore, I would like to rerun all data only once, and then add the result 
> files depending on different criteria.
> 
> Of course, I tried to write a script that does the adding. But somehow it is 
> incredibly slow. And I am not the Master Of C++, too.
> 
> Is there any deeper reason for MIDAS using TFolders, not TDirectorys? ROOT's 
> hadd can treat TDirectory. Can I simply patch "my" MIDAS? Is there general 
> interest in a change like this? (Does anyone have experience with the speed of 
> hadd?)
> 
> Looking forward to comments from the Forum.
> 
> Cheers,
> 
> Randolf

Dear Forum,

I have this beautiful Intel Quadcore with fast disks, but MIDAS does obviously 
only make use of one CPU at a time. Has anyboy of you already done some work 
on making MIDAS parallel? Event-based data analysis should be the best 
candidate for this.

Has anybody done this with PVM? There is some PVM-related stuff in the MIDAS 
sources, but I got the impression this works only with HBOOK, not with ROOT. 
Or am I wrong?
But then PVM is probably also not the most efficient thing one ONE machine 
with multiple CPUs, right? And finally, with PVM we're back to 
adding .root-files efficiently (see my previous post).

Any thoughts?

Cheers,

Randolf

> I have this beautiful Intel Quadcore with fast disks, but MIDAS does obviously 
> only make use of one CPU at a time. Has anyboy of you already done some work 
> on making MIDAS parallel? Event-based data analysis should be the best 
> candidate for this.

There are ring buffer routines rb_xxx for distributed event analysis, but this is
currently only implemented in the front-end framework. These routines are pretty
simple, and their integration into the analyzer should not be very difficult.
Unfortunately I don't have time for that right now. We do our analysis such that we
analyze four different runs in parallel on a quadcore machine.

- Stefan

Dear Stephan,

I am writting on behalf of the LiBeRACE collaboration
at Berkeley/Livermore.

We are trying to use midas (2.0.0) for our acquisition system.
However we had some difficulties to compile it on LINUX Fedora
Core 6 with gcc 4.1.1
I tried to trace back the problem and I found that _syscall0 in
system.c is actually an obsolete call (since gcc 4.x apparently).
Playing with assembly language being behond my competence, I would 
like to know if you ever came across this situation recently and
if you have any suggestion(s).

With my best regards
Julien GIBELIN


------------------------------------------------------
GIBELIN Julien

Lawrence Berkeley National Laboratory
Nuclear Science Division
One Cyclotron Rd.
MS 88R0192
BERKELEY, CA 94720-8101

Tel: +1 (510) 495-2695
Fax: +1 (510) 486-7983
------------------------------------------------------

> Dear Stephan,
> 
> I am writting on behalf of the LiBeRACE collaboration
> at Berkeley/Livermore.
> 
> We are trying to use midas (2.0.0) for our acquisition system.
> However we had some difficulties to compile it on LINUX Fedora
> Core 6 with gcc 4.1.1
> I tried to trace back the problem and I found that _syscall0 in
> system.c is actually an obsolete call (since gcc 4.x apparently).
> Playing with assembly language being behond my competence, I would 
> like to know if you ever came across this situation recently and
> if you have any suggestion(s).

The '_syscall0' function call was replaced by 'syscall' in SVN revision 3583. I
would recommend that you switch to the current SVN version (see
http://ladd00.triumf.ca/~daqweb/doc/midas/html/quickstart.html on how to obtain
the SVN version). If the problem still persists, please let us know.

- Stefan

Hi,
    I found that midas banks can be given an extra 32 bits of zeros when
trying to keep to 32bit boundary on my x86_64. 

This can be fixed by changing (in midas.h)
#define ALIGN8(x)  (((x)+7) & ~7)
to
#define ALIGN8(x)  (((x)+3) & ~3)

Is there any bad consequences doing this?

> Hi,
>     I found that midas banks can be given an extra 32 bits of zeros when
> trying to keep to 32bit boundary on my x86_64. 
> 
> This can be fixed by changing (in midas.h)
> #define ALIGN8(x)  (((x)+7) & ~7)
> to
> #define ALIGN8(x)  (((x)+3) & ~3)
> 
> Is there any bad consequences doing this?

Yes. ALIGN8 means 'align to 8-byte boundary' (64-bit), and if you change that, you
break the code at various locations. Furthermore, 8-byte aligned access is faster
on x86_64 than 4-byte aligned access, so you will get a performance penalty. If
course if you have very many small banks, the zero padding can cause some
overhead, but in that case you could combine some data into a single bank.

The ROODY online histogram viewer and the ROOTANA midas analyzer toolkit have been updated to work 
with ROOT version 5.16 and tested on Linux (SL4.4) and MacOS (10.4.10/PPC).

This update includes the library called "TNetDirectory" for access to remote ROOT objects. This library is 
still under development, but is complete enough for use with ROODY. To try it, please specify -P9091 in 
rootana and -Plocalhost:9091 in ROODY.

K.O.

We had the problem that different experiments used different MAX_EVENT_SIZE
values (the MEG experiment actually 10 MB!). If each experiment changes the
value in midas.h and accidentally commits it, other experiments are affected.
Therefore I modified midas.h and the Makefile to accept a new environment
variable MIDAS_MAX_EVENT_SIZE. If this value is set, the Makefile passes it's
value to midas.h where it supersedes the default value which is currently at 4 MB.

PAA: Can you pleas add this to the documentation at the right spot? Thanks.

I am having problems with handling the end-of-run situation in my midas
frontend. I have a device that continuously sends data (over USB) and I read
this data in my "read_event" function.

Everything is good until the end-of-run, at which time this happens:
0) mfe.c calls my read_event() to read the data (loop until the end-of-run
transition)
1) mfe.c calls my end_of_run()
2) here, I tell the device "please stop sending data"
3) all seems good, but wait!!!
4) there is all this data generated between step 0 and step 2 still sitting
inside the device and it has nowhere to go: the run is ended, the output file is
closed, my read_event() will never be called ever again (well, until the next run).

It seems to me mfe.c needs to have one more function, something like
"pre_end_of_run()" that works like this:
0) mfe.c calls my read_event() to read the data (loop until the end-of-run
transition)
1) mfe.c calls pre_end_of_run(), here I tell the device to stop sending data
2) mfe.c calls read_event() for the very last time, to give me the opportunity
to read and send away any data I still may have.
3) mfe.c calls the end_of_run(). The run is truely finished.

Any thoughts?

K.O.

> I am having problems with handling the end-of-run situation in my midas
> frontend. I have a device that continuously sends data (over USB) and I read
> this data in my "read_event" function.
> 
> Everything is good until the end-of-run, at which time this happens:
> 0) mfe.c calls my read_event() to read the data (loop until the end-of-run
> transition)
> 1) mfe.c calls my end_of_run()
> 2) here, I tell the device "please stop sending data"
> 3) all seems good, but wait!!!
> 4) there is all this data generated between step 0 and step 2 still sitting
> inside the device and it has nowhere to go: the run is ended, the output file is
> closed, my read_event() will never be called ever again (well, until the next run).
> 
> It seems to me mfe.c needs to have one more function, something like
> "pre_end_of_run()" that works like this:
> 0) mfe.c calls my read_event() to read the data (loop until the end-of-run
> transition)
> 1) mfe.c calls pre_end_of_run(), here I tell the device to stop sending data
> 2) mfe.c calls read_event() for the very last time, to give me the opportunity
> to read and send away any data I still may have.
> 3) mfe.c calls the end_of_run(). The run is truely finished.
> 
> Any thoughts?

You can achieve the desired functionality without changing mfe.c:

0) mfe.c calls read_event
1) mfe.c calls end_of_run. Your end_of_run tells the device to stop data and flushes
the remaining data. At this point you have to re-make actually a part of the mfe.c
functionality, but basically you need a bm_compose_event() and a bm_send_event(), so
just a few lines of code. If you want to have the final event number right in your
equipment, you also need to update eq->events_sent accordingly. 

Given the fact that 99% of the experiments do not need this functionality, I propose
that we keep mfe.c and you add the few lines of code into your user part of the
specific frontend.

Stefan

I now commited the changes to mlogger (mlogger.c, msystem.h) implementing data
compression using zlib (svn revision 3845)

To enable compression, observe that mlogger is compiled with -DHAVE_ZLIB (see
the Makefile), in "/Logger/Channels/NNN/Settings", set "compression" to "1" and
the filename to "run%05d.mid.gz" (note the suffix ".gz").

In the Makefile, I only enabled HAVE_ZLIB for Linux, as that is the only
platform I tested. If somebody can test compression on Windows, please do and
let us know.

My ROOT analyzer (rootana) package can read compressed MIDAS files directly and
if one wants to add this capability to other MIDAS-related packages, one is
welcome to use my TMidasFile.cxx as an example
(http://ladd00.triumf.ca/viewcvs/rootana/trunk/TMidasFile.cxx?view=markup).

K.O.

I commited the latest driver for the Wiener CCUSB USB-CAMAC driver. It
implements all functions from mcstd.h and has been tested to be plug-compatible
with at least one of our CAMAC frontends. K.O.

> I commited the latest driver for the Wiener CCUSB USB-CAMAC driver. It
> implements all functions from mcstd.h and has been tested to be plug-compatible
> with at least one of our CAMAC frontends. K.O.

This driver is known to not work with the latest CCUSB firmware (20x, 204, 30x, 303). I know what 
modifications are required and an updated driver will be available shortly. If there is a delay, and you need the 
driver ASAP, please drop me an email.

Also, I am thinking about dropping support for the very old CCUSB firmware revisions (before 204). (Any 
comments?)

K.O.

> > I commited the latest driver for the Wiener CCUSB USB-CAMAC driver. It
> > implements all functions from mcstd.h and has been tested to be plug-compatible
> > with at least one of our CAMAC frontends. K.O.

Well, it took almost a year to finish an updated driver, which has now been
commited to MIDAS SVN (see http://savannah.psi.ch/viewcvs/trunk/drivers/camac/ccusb/?root=midas).

This supports ccusb firmware release 0x402. With earlier firmware, simple CAMAC operations should work,
but to use the readout list feature one has to have the latest main firmware (0x402 as of today) and the latest CPLD
firmware.

The driver kit includes:
- the "ccusb" driver which implements the MIDAS mcstd.h CAMAC interface;
- test_ccusb to probe the interface and generally make the lights flash;
- ccusb_flash for updating the ccusb main firmware (assembled from bits and pieces found on the CCUSB driver CD);
- feccusb, an example midas frontend, which uses the ccusb readout list feature and has extensive error handling,
should be good enough for production use (unlike the Wiener libxxusb drivers, which lack basic error handling).
- analyzer.cxx, an rootana-based example on how to decode the ccusb data;
- README file with release notes.

If you use this driver, please drop me an email (even if it works perfectly for you, hah!) - the ccusb device is very
nice but can be hard to use and I would like to hear about problems other people have with it.

Today's version of the README files is attached below:

MIDAS driver for the Wiener/JTec CC-USB CAMAC-USB interface.

Date: 22-AUG-2007/KO

Note 1: The CC-USB interface comes with a CD which contains manuals,
firmware files, Windows and Linux software. The Wiener/JTec driver
is called "libxxusb". These MIDAS/musbstd drivers were written before
libxxusb bacame available and do not use libxxusb.

This driver implements the MIDAS CAMAC interafce "mcstd.h" using
the MIDAS USB interface musbstd.h.

Note 2: There exist many revisions of CCUSB firmware. Basic CAMAC
access works in all of them, but the "readout list" feature seems
to be only functional with firmware revision 0x402 or older and
with CPLD revisions CC_atmmgr_101406.jed, CC_datamgr_021905.jed,
CC_lammgr_brdcst_041906.jed or older.

To upgrade the main CCUSB firmware, follow instructions from
the CCUSB manual. On Linux, one can use the ccusb_flash
program included with these MIDAS drivers. It is a copy
of ccusb_flash from the Wiener CD, with all the pieces
assembled into one place and with a working Makefile. (I am too
lazy to add the flashing bits to the ccusb.c driver).

To upgrade the CPLD firmware, one needs a Xilinx JTag programmer
cable (we use a "parallel port to JTag" cable provided by Wiener),
and the Xilinx software (on Linux, we use Xilinx91i). For successful
upgrade, follow instructions from Xilinx and Wiener.

Note 3: Before starting to use the CCUSB interface, one should obtain
the latest version of the CCUSB manual and firmware by downloading
the latest version the CCUSB driver CD from the Wiener web
site (registration required)

Note 4: The example CCUSB frontend assumes this hardware configuration:
LeCroy 2249A 12 channel ADC in slot 20, Kinetic Systems 3615 6 channel
scaler in slot 12. NIM trigger input connected to CCUSB input "I1"
firing at 10-100 Hz. Without the external trigger CCUSB will not
generate any data and the frontend will only give "data timeout"
errors. With the trigger, the LED on the scaler should flash at 1 Hz
and the LEDs on the CCUSB should flash at the trigger rate.

Note 5: The CCUSB interface does not reliably power up in some CAMAC
crates (this has something to do with the sequence in which
different voltages start at different times with different CAMAC
power supplies). Some newer CCUSB modules may have this
problem fixed in the hardware and in the CPLD firmware. For modules
exhibiting this problem (i.e. no USB communication after power up),
try to cycle the power several time, or implement the "hardware reset
switch" (ask Wiener).

Note 6: The CCUSB firmware is very fickle and would crash if you look
at it the wrong way. This MIDAS driver tries to avoid all known crashers
and together with the example frontend, can recover from some
of them. Other crashes cannot be recovered from other than by
a hardware reset or power cycle.

//end

I had to change the pointer type of mvme_read and mvme_write to (void *) instead
to (mvme_locaddr_t *) to avoid warnings under 64-bit linux. Please adjust your
VME drivers if necessary.

- Stefan

> I had to change the pointer type of mvme_read and mvme_write to (void *) instead
> to (mvme_locaddr_t *) to avoid warnings under 64-bit linux. Please adjust your
> VME drivers if necessary.

Updated: vmicvme.c (VMIVME-7750/7805) and gefvme.c (GEFANUC V7865)

K.O.

I commited a few minor changes to musbstd and mscb code to make them work on
MacOSX (tested on 10.3.9) and Linux (tested on Fedora 6).

The basic functions work with the MSCB USB master, but I still need to
investigate some cases where the connection hangs and usb communications do not
work until the USB cable is unplugged and plugged back in. I see this problem
both on MacOS and Linux.

Important changes:
1) mscb_select_device() does not work on both Linux and MacOS and is disabled.
Please run "msc -d usb0".
2) on Linux, the Makefile should define -DOS_LINUX and -DHAVE_LIBUSB;
   on MacOS, the Makefile should define -DOS_LINUX and -DOS_DARWIN. (This is
because MacOS is treated as a funny type of Linux).
3) when doing USB communications, one has to use the correct endpoint numbers,
which seem to be system dependant and for now, I hard code them in mscb.c for
the tested systems.

There supposed to be no changes to the Windows code, but I cannot test on
Windows, so if somebody does and finds breakage, please let me know.

K.O.

> I commited a few minor changes to musbstd and mscb code...
>
> The basic functions work with the MSCB USB master, but I still need to
> investigate some cases where the connection hangs and usb communications do not
> work until the USB cable is unplugged and plugged back in. I see this problem
> both on MacOS and Linux.

I think I fixed the hangs we see on linux and macos - at the end all I had to do is
issue a usb reset to make mscb communicate again.

Also tested on Linux FC6 and SL4.5.

K.O.

FWIW, I am running latest 32-bit MIDAS on an AM2 dual core AMD machine under 64-bit SL5. Everything 
seems to work correctly. K.O.

P.S. For the record, the compiler produces two sets of warnings:
- warning: pointer targets in passing argument 3 of â differ in signedness
- warning: dereferencing type-punned pointer will break strict-aliasing rules
(I do not understand the meaning of the second warning. type-punned pointer, huh?)
K.O.

#include <stdio.h>
  
int main(){
   int ii = 1;
   float* ff = (float*)&ii;
   *ff = 2;
   printf("%d\n", ii);
   return 0;
} 

warning: dereferencing type-punned pointer will break strict-aliasing rules

#include <stdio.h>

typedef struct xxx {int ii;} XX;
  
int main(){
   XX a;
   a.ii = 1;
   *(short*)&a.ii = 0;
   printf("%d\n", a.ii);
   return 0;
}

#include <stdio.h>
#include <string.h>
#include <malloc.h>
  
int main(){
   int *ii = (int*)malloc(8);
   ii[0] = 1;
   ii[1] = 2;
   float* ff = (float*)ii;
   ff[0] = 3;
   ff[1] = 4;
   printf("%d %d\n", ii[0], ii[1]);
   return 0;
}