Back Midas Rome Roody Rootana
  Midas DAQ System, Page 112 of 137  Not logged in ELOG logo
New entries since:Wed Dec 31 16:00:00 1969
ID Date Author Topic Subjectup
  2420   08 Aug 2022 Konstantin OlchanskiInfomidas on ubuntu LTS 22.04
reporting that as of commit 78f707c0686d22f8329c7a1f1c46d7dccf35ceff, midas builds 
without errors or warnings on Ubuntu LTS 22.04, 20.04, CentOS-7 and MacOS 12.4. 
(except for some warnings from mscb and msc). K.O.
  919   22 Oct 2013 Konstantin OlchanskiInfomidas programs "auto start", etc
MIDAS "programs" settings include: /programs/xxx/"auto start", "auto restart" and "auto stop". What do 
they do?

"auto start":

if set to "y", the program's "start command" will be unconditionally executed at the beginning of the run 
start transition.

Because there are no checks or tests, the "start command" will be executed even if the program is already 
running. It means that this function cannot be used to start frontend programs - a new copy will be 
started each time, and a previously running copy will be killed.

Also the timing of the program startup and run transition is wrong - in my tests, the program starts too 
late to see the run transition. If the program is a frontend, it will never see the begin-of-run transition.

1st conclusion: "auto start" should be "n" for frontend programs and for any other programs that are 
supposed to be continuously running (mlogger, lazylogger, etc).

2nd conclusion: "auto start" does the same thing as "/programs/execute on start run".

"auto stop":

if set to "y", the program will be stopped after the end of run. (using cm_shutdown).

"auto restart":

this has nothing to do with starting and stopping runs. Instead, it works in conjunction with the alarm 
system and the "program is not running" alarm.

The alarm system periodically calls al_check(). al_check() checks all programs defined under /Programs to 
see if they are running (using cm_exist()). If a program is not running and an alarm is defined, the alarm is 
raised ("program is not running" alarm). If there is a start command and "auto restart" is set to "y", the 
start command is executed.

When using these "auto start" and "auto restart" functions, one needs to be careful about the context 
where the start command will be executed: midas clients may be running from different directories, under 
different user names and on different computers.

In "auto start", the start command is executed from cm_transition. For remote clients, this will happen on 
the remote computer. (against the expectation that the program will be started on the main computer).

In "auto restart", the start command is executed by al_check() which always runs locally (for remote 
clients, it runs inside the mserver). So the started program will always run on the main computer, but 
maybe not in the same directory as when started from the mhttpd "programs -> start" button.

Conclusion:

"programs auto start" : works but has strange interactions and side effects, do not use it.
"programs auto stop" : works, can be used to stop programs at the end of run (but what for?)
"programs auto restart" : works, seems to work correctly, can be used to auto restart mlogger, frontends, 
etc.

K.O.
  926   06 Nov 2013 Stefan RittInfomidas programs "auto start", etc
> "programs auto start" : works but has strange interactions and side effects, do not use it.
> "programs auto stop" : works, can be used to stop programs at the end of run (but what for?)
> "programs auto restart" : works, seems to work correctly, can be used to auto restart mlogger, frontends, 

auto start and auto stop have been requested by PAA loooong time ago. Maybe he remembers if/where this has been used at all. I never used it. So if 
this is the case for others, we can easily change it and won't break anything. Like auto start can be executed before the run transition happens, check 
for a previous version of the program, and only continue when the program is actually running. Should be only a few lines of code. Auto restart is used 
successfully here at PSI, for example for the lazy logger.

/Stefan
  771   27 Jun 2011 Konstantin OlchanskiInfomidas shared memory changes
A number of changes were made to the midas shared memory implementation for
Linux and MacOS:

1) SysV or POSIX shared memory compile-type choice is removed. Both shared
memory types are compiled-in and are selected at run time.
2) the shared memory type used by an experiment is recorded in the file
.SHM_TYPE.TXT. Currently implemented are "POSIXv2_SHM" (the new default for new
experiments), "POSIX_SHM", "MMAP_SHM" and "SYSV_SHM". (see system.c) (MMAP_SHM
is fully functional but is not recommended). The POSIXv2_SHM uses an improved
filename scheme (on Linux, see "ls -l /dev/shm") and permits multiple
experiments to coexist on a MacOS computer (where there is a severe limit on
shared memory filename length).
3) following a number of mishaps where "odbedit" has been run on the wrong
computer (causing havoc with ODB and .xxx.SHM files), for each experiment, the
hostname of the computer where the ODB shared memory is meant to reside is now
recorded in the file .SHM_HOST.TXT. Typically, this is the machine running
mserver, mhttpd and mlogger. If some client is accidentally started on the wrong
machine or if MIDAS_SERVER_HOST is accidentally left undefined, MIDAS will now
print a stern message reporting the hostname mismatch, tell the user to use the
mserver and refuse to run. The user has the choice of starting the client on the
correct computer (as reported in the error message), using the mserver (start
client with -H flag) or edit/delete the .SHM_HOST.TXT file (full pathname is
reported by the error message).

With this update, MIDAS on MacOS becomes fully functional (before, only one
experiment could be used at a time).

svn rev 5105
K.O.
  773   05 Jul 2011 Konstantin OlchanskiInfomidas shared memory changes
> 2) the shared memory type used by an experiment is recorded in the file .SHM_TYPE.TXT.

An error with creating the file .SHM_TYPE.TXT was corrected in system.c svn rev 5125 - if file did not exist, it is 
created correctly, but MIDAS reports "cannot connect to ODB". Second try works correctly because the file exists 
now.

> 3) the hostname of the computer where the ODB shared memory is meant to reside is now
> recorded in the file .SHM_HOST.TXT.

This is causing problems on mobile computers where "hostname" changes all the time (i.e. set according to 
DHCP on whatever network happens to be connected).

If you run into this problem, keep deleting .SHM_HOST.TXT or use this workaround: disable the hostname check 
by making the file .SHM_HOST.TXT empty (zero length).

K.O.
  775   10 Jul 2011 Konstantin OlchanskiBug Fixmidas shared memory changes
> > 2) the shared memory type used by an experiment is recorded in the file .SHM_TYPE.TXT.
> > 3) the hostname of the computer where the ODB shared memory is meant to reside is now
> > recorded in the file .SHM_HOST.TXT.

Due to a typo in src/system.c svn rev 5125, ss_shm_delete() did not work at all. This broke "odbedit -R", "odbedit -s 5000000" (to change ODB size), etc. 
Fixed in src/system.c svn rev 5134. (It is safe to update just tis one file to fix this problem).

Sorry for the inconvenience,
K.O.
  776   11 Jul 2011 Konstantin OlchanskiBug Fixmidas shared memory changes
> > > 2) the shared memory type used by an experiment is recorded in the file .SHM_TYPE.TXT.
> > > 3) the hostname of the computer where the ODB shared memory is meant to reside is now
> > > recorded in the file .SHM_HOST.TXT.


Because the mserver did not setup correct experiment name and path, POSIX shared memory did not work at all when used with the mserver. Fixed in mserver.c rev 5135


Sorry for the inconvenience,
K.O.
  91   20 Nov 2003 Konstantin Olchanski midas timeout wraparound
While reviving midas on midtig01 after it was not used for a while, we see
this. Notice negative "last called" numbers. Looks like a time_t wraparound
somewhere...

[local:tigress:S]/>scl -w
Name                Host                Timeout    Last called
mhttpd              midtig01.triumf.ca  10000      -2037131082
Logger              midtig01.triumf.ca  10000      -2037131166
Analyzer            midtig01.triumf.ca  10000      -2037131048
JACQ                midtig01.triumf.ca  10000      -2037131667
mhttpd1             midtig01.triumf.ca  10000      325
ODBEdit             midtig01.triumf.ca  10000      829

K.O.
  805   20 Jun 2012 Konstantin OlchanskiInfomidas vme benchmarks
I am recording here the results from a test VME system using two VF48 waveform digitizers and a 64-bit 
dual-core VME processor (V7865). VF48 data suppression is off, VF48 modules set to read 48 channels, 
1000 ADC samples each. mlogger data compression is enabled (gzip -1).

Event rate is about 200/sec
VME Data rate is about 40 Mbytes/sec
System is 100% busy (estimate)

System utilization of host computer (dual-core 2.2GHz, dual-channel DDR333 RAM):

(note high CPU use by mlogger for gzip compression of midas files)

top - 12:23:45 up 68 days, 20:28,  3 users,  load average: 1.39, 1.22, 1.04
Tasks: 193 total,   3 running, 190 sleeping,   0 stopped,   0 zombie
Cpu(s): 32.1%us,  6.2%sy,  0.0%ni, 54.4%id,  2.7%wa,  0.1%hi,  4.5%si,  0.0%st
Mem:   3925556k total,  3797440k used,   128116k free,     1780k buffers
Swap: 32766900k total,        8k used, 32766892k free,  2970224k cached

  PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND                                   
 5169 trinat    20   0  246m 108m  97m R 64.3  2.8  29:36.86 mlogger                                    
 5771 trinat    20   0  119m  98m  97m R 14.9  2.6 139:34.03 mserver                                    
 6083 root      20   0     0    0    0 S  2.0  0.0   0:35.85 flush-9:3                                  
 1097 root      20   0     0    0    0 S  0.9  0.0  86:06.38 md3_raid1        

System utilization of VME processor (dual-core 2.16 GHz, single-channel DDR2 RAM):

(note the more than 100% CPU use of multithreaded fevme)

top - 12:24:49 up 70 days, 19:14,  2 users,  load average: 1.19, 1.05, 1.01
Tasks: 103 total,   1 running, 101 sleeping,   1 stopped,   0 zombie
Cpu(s):  6.3%us, 45.1%sy,  0.0%ni, 47.7%id,  0.0%wa,  0.2%hi,  0.6%si,  0.0%st
Mem:   1019436k total,   866672k used,   152764k free,     3576k buffers
Swap:        0k total,        0k used,        0k free,    20976k cached

  PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND                                   
19740 trinat    20   0  177m 108m  984 S 104.5 10.9   1229:00 fevme_gef.exe                             
 1172 ganglia   20   0  416m  99m 1652 S  0.7 10.0   1101:59 gmond                                      
32353 olchansk  20   0 19240 1416 1096 R  0.2  0.1   0:00.05 top                                        
  146 root      15  -5     0    0    0 S  0.1  0.0  42:52.98 kslowd001       

Attached are the CPU and network ganglia plots from lxdaq09 (VME) and ladd02 (host).

The regular bursts of "network out" on ladd02 is lazylogger writing mid.gz files to HADOOP HDFS.

K.O.
Attachment 1: lxdaq09cpu.gif
lxdaq09cpu.gif
Attachment 2: lxdaq09net.gif
lxdaq09net.gif
Attachment 3: ladd02cpu.gif
ladd02cpu.gif
Attachment 4: ladd02net.gif
ladd02net.gif
  806   20 Jun 2012 Konstantin OlchanskiInfomidas vme benchmarks
> I am recording here the results from a test VME system using two VF48 waveform digitizers

Note 1: data compression is about 89% (hence "data to disk" rate is much smaller than the "data from VME" rate)

Note 2: switch from VME MBLT64 block transfer to 2eVME block transfer:
- raises the VME data rate from 40 to 48 M/s
- event rate from 220/sec to 260/sec
- mlogger CPU use from 64% to about 80%

This is consistent with the measured VME block transfer rates for the VF48 module: MBLT64 is about 40 M/s, 2eVME is about 50 M/s (could be 
80 M/s if no clock cycles were lost to sync VME signals with the VF48 clocks), 2eSST is implemented but impossible - VF48 cannot drive the 
VME BERR and RETRY signals. Evil standards, grumble, grumble, grumble).

K.O.
  807   21 Jun 2012 Stefan RittInfomidas vme benchmarks
Just for completeness: Attached is the VME transfer speed I get with the SIS3100/SIS1100 interface using 
2eVME transfer. This curve can be explained exactly with an overhead of 125 us per DMA transfer and a 
continuous link speed of 83 MB/sec.
Attachment 1: Screen_Shot_2012-06-21_at_10.14.09_.png
Screen_Shot_2012-06-21_at_10.14.09_.png
  809   21 Jun 2012 Konstantin OlchanskiInfomidas vme benchmarks
> Just for completeness: Attached is the VME transfer speed I get with the SIS3100/SIS1100 interface using 
> 2eVME transfer. This curve can be explained exactly with an overhead of 125 us per DMA transfer and a 
> continuous link speed of 83 MB/sec.

What VME module is on the other end?

K.O.
  810   22 Jun 2012 Stefan RittInfomidas vme benchmarks
> > Just for completeness: Attached is the VME transfer speed I get with the SIS3100/SIS1100 interface using 
> > 2eVME transfer. This curve can be explained exactly with an overhead of 125 us per DMA transfer and a 
> > continuous link speed of 83 MB/sec.
> 
> What VME module is on the other end?
> 
> K.O.

The PSI-built DRS4 board, where we implemented the 2eVME protocol in the Virtex II FPGA. The same speed can be obtained with the commercial 
VME memory module CI-VME64 from Chrislin Industries (see http://www.controlled.com/vme/chinp1.html).

Stefan
  812   24 Jun 2012 Konstantin OlchanskiInfomidas vme benchmarks
> > > Just for completeness: Attached is the VME transfer speed I get with the SIS3100/SIS1100 interface using 
> > > 2eVME transfer. This curve can be explained exactly with an overhead of 125 us per DMA transfer and a 
> > > continuous link speed of 83 MB/sec.
>
> [with ...]  the PSI-built DRS4 board, where we implemented the 2eVME protocol in the Virtex II FPGA.

This is an interesting hardware benchmark. Do you also have benchmarks of the MIDAS system using the DRS4 (measurements
of end-to-end data rates, maximum event rate, maximum trigger rate, any tuning of the frontend program
and of the MIDAS experiment to achieve those rates, etc)?

K.O.
  813   24 Jun 2012 Konstantin OlchanskiInfomidas vme benchmarks
> > I am recording here the results from a test VME system using two VF48 waveform digitizers

(I now have 4 VF48 waveform digitizers, so the event rates are half of those reported before. Date rate
is up to 51 M/s - event size has doubled, per-event overhead is the same, so the effective data rate goes 
up).

This message demonstrates the effects of tuning the MIDAS system for high rate data taking.

Attached is the history plot of the event rate counters which show the real-time performance of the MIDAS 
system with better detail compared to the average event rate reported on the MIDAS status page. For an 
ideal real-time system, the event rate should be a constant, without any drop-outs.

Seen on the plot:

run 75: the periodic dropouts in the event rate correspond to the lazylogger writing data into HADOOP 
HDFS. Clearly the host computer cannot keep up with both data taking and data archiving at the same 
time. (see the output of "top" "with HDFS" and "without HDFS" below)

run 76: SYSTEM buffer size increased from 100Mbytes to 300Mbytes. Maybe there is an improvement.

run 77-78: "event_buffer_size" inside the multithreaded (EQ_MULTITHREAD) VME frontend increased from 
100Mbytes to 300Mbytes. (6 seconds of data at 50M/s). Much better, yes?

Conclusion: for improved real-time performance, there should be sufficient buffering between the VME 
frontend readout thread and the mlogger data compression thread.

For benchmark hardware, at 50M/s, 4 seconds of buffer space (100M in the SYSTEM buffer and 100M in 
the frontend) is not enough. 12 seconds of buffer space (300+300) is much better. (Or buy a faster 
backend computer).


P.S. HDFS data rate as measured by lazylogger is around 20M/s for CDH3 HADOOP and around 30M/s for 
CDH4 HADOOP.

P.S. Observe the ever present unexplained event rate fluctuations between 130-140 event/sec.


K.O.


---- "top" output during normal data taking, notice mlogger data compression consumes 99% CPU at 51 
M/s data rate.

top - 08:55:22 up 72 days, 17:00,  5 users,  load average: 2.47, 2.32, 2.27
Tasks: 206 total,   2 running, 204 sleeping,   0 stopped,   0 zombie
Cpu(s): 52.2%us,  6.1%sy,  0.0%ni, 34.4%id,  0.8%wa,  0.1%hi,  6.2%si,  0.0%st
Mem:   3925556k total,  3064928k used,   860628k free,     3788k buffers
Swap: 32766900k total,   200704k used, 32566196k free,  2061048k cached

  PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND                                                
 5826 trinat    20   0  437m 291m 287m R 97.6  7.6 636:39.63 mlogger                                                 
27617 trinat    20   0  310m 288m 288m S 24.6  7.5   6:59.28 mserver                                                 
 1806 ganglia   20   0  415m  62m 1488 S  0.9  1.6 668:43.55 gmond       


--- "top" output during lazylogger/HDFS activity. Observe high CPU use by lazylogger and fuse_dfs (the 
HADOOP HDFS client). Observe that CPU use adds up to 167% out of 200% available.

top - 08:57:16 up 72 days, 17:01,  5 users,  load average: 2.65, 2.35, 2.29
Tasks: 206 total,   2 running, 204 sleeping,   0 stopped,   0 zombie
Cpu(s): 57.6%us, 23.1%sy,  0.0%ni,  8.1%id,  0.0%wa,  0.4%hi, 10.7%si,  0.0%st
Mem:   3925556k total,  3642136k used,   283420k free,     4316k buffers
Swap: 32766900k total,   200692k used, 32566208k free,  2597752k cached

  PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND                                                
 5826 trinat    20   0  437m 291m 287m R 68.7  7.6 638:24.07 mlogger                                                 
23450 root      20   0 1849m 200m 4472 S 64.4  5.2  75:35.64 fuse_dfs                                                
27617 trinat    20   0  310m 288m 288m S 18.5  7.5   7:22.06 mserver                                                 
26723 trinat    20   0 38720  11m 1172 S 17.9  0.3  22:37.38 lazylogger                                              
 7268 trinat    20   0 1007m  35m 4004 D  1.3  0.9 187:14.52 nautilus                                                
 1097 root      20   0     0    0    0 S  0.8  0.0 101:45.55 md3_raid1   
Attachment 1: Scalers_(1).gif
Scalers_(1).gif
  814   25 Jun 2012 Stefan RittInfomidas vme benchmarks
> P.S. Observe the ever present unexplained event rate fluctuations between 130-140 event/sec.

An important aspect of optimizing your system is to keep the network traffic under control. I use GBit Ethernet between FE and BE, and make sure the switch 
can accomodate all accumulated network traffic through its backplane. This way I do not have any TCP retransmits which kill you. Like if a single low-level 
ethernet packet is lost due to collision, the TCP stack retransmits it. Depending on the local settings, this can be after a timeout of one (!) second, which 
punches already a hole in your data rate. On the MSCB system actually I use UDP packets, where I schedule the retransmit myself. For a LAN, 10-100ms timeout 
is there enough. The one second is optimized for a WAN (like between two continents) where this is fine, but it is not what you want on a LAN system. Also 
make sure that the outgoing traffic (lazylogger) uses a different network card than the incoming traffic. I found that this also helps a lot.

- Stefan
  815   25 Jun 2012 Konstantin OlchanskiInfomidas vme benchmarks
> > P.S. Observe the ever present unexplained event rate fluctuations between 130-140 event/sec.
> 
> An important aspect of optimizing your system is to keep the network traffic under control. I use GBit Ethernet between FE and BE, and make sure the switch 
> can accomodate all accumulated network traffic through its backplane. This way I do not have any TCP retransmits which kill you. Like if a single low-level 
> ethernet packet is lost due to collision, the TCP stack retransmits it. Depending on the local settings, this can be after a timeout of one (!) second, which 
> punches already a hole in your data rate. On the MSCB system actually I use UDP packets, where I schedule the retransmit myself. For a LAN, 10-100ms timeout 
> is there enough. The one second is optimized for a WAN (like between two continents) where this is fine, but it is not what you want on a LAN system. Also 
> make sure that the outgoing traffic (lazylogger) uses a different network card than the incoming traffic. I found that this also helps a lot.
> 

In typical applications at TRIUMF we do not setup a private network for the data traffic - data from VME to backend computer
and data from backend computer to DCACHE all go through the TRIUMF network.

This is justified by the required data rates - the highest data rate experiment running right now is PIENU - running
at about 10 M/s sustained, nominally April through December. (This is 20% of the data rate of the present benchmark).

The next highest data rate experiment is T2K/ND280 in Japan running at about 20 M/s (neutrino beam, data rate
is dominated by calibration events).

All other experiments at TRIUMF run at lower data rates (low intensity light ion beams), but we are planning for an experiment
that will run at 300 M/s sustained over 1 week of scheduled beam time.

But we do have the technical capability to separate data traffic from the TRIUMF network - the VME processors and
the backend computers all have dual GigE NICs.

(I did not say so, but obviously the present benchmark at 50 M/s VME to backend and 20-30 M/s from backend to HDFS is a GigE network).

(I am not monitoring the TCP loss and retransmit rates at present time)

(The network switch between VME and backend is a "the cheapest available" rackmountable 8-port GigE switch. The network between
the backend and the HDFS nodes is mostly Nortel 48-port GigE edge switches with single-GigE uplinks to the core router).

K.O.
  816   26 Jun 2012 Konstantin OlchanskiInfomidas vme benchmarks
> > > I am recording here the results from a test VME system using four VF48 waveform digitizers

Now we look at the detail of the event readout, or if you want, the real-time properties of the MIDAS 
multithreaded VME frontend program.

The benchmark system includes a TRIUMF-made VME-NIMIO32 VME trigger module which records the 
time of the trigger and provides a 20 MHz timestamp register. The frontend program is instrumented to 
save the trigger time and readout timing data into a special "trigger" bank ("VTR0"). The ROOTANA-based 
MIDAS analyzer is used to analyze this data and to make these plots.

Timing data is recorded like this:

NIM trigger signal ---> latched into the IO32 trigger time register (VTR0 "trigger time")
...
int read_event(pevent, etc) {
VTR0 "trigger time" = io32->latched_trigger_time();
VTR0 "readout start time" = io32->timestamp();
read the VF48 data
io32->release_busy();
VTR0 "readout end time" = io32->timestamp();
}

From the VTR0 time data, we compute these values:

1) "trigger latency" = "readout start time" - "trigger time" --- the time it takes us to "see" the trigger
2) "readout time" = "readout end time" - "readout start time" --- the time it takes to read the VF48 data
3) "busy time" = "readout end time" - "trigger time" --- time during which the "DAQ busy" trigger veto is 
active.
also computed is
4) "time between events" = "trigger time" - "time of previous trigger"

And plot them on the attached graphs:

1) "trigger latency" - we see average trigger latency is 5 usec with hardly any events taking more than 10 
usec (notice the log Y scale!). Also notice that there are 35 events that took longer that 100 usec (0.7% out 
of 5000 events).

So how "real time" is this? For "hard real time" the trigger latency should never exceed some maximum, 
which is determined by formal analysis or experimentally (in which case it will carry an experimental error 
bar - "response time is always less than X usec with probability 99.9...%" - the better system will have 
smaller X and more nines). Since I did not record the maximum latency, I can only claim that the 
"response time is always less than 1 sec, I am pretty sure of it".

For "soft real time" systems, such as subatomic particle physics DAQ systems, one is permitted to exceed 
that maximum response time, but "not too often". Such systems are characterized by the quantities 
derived from the present plot (mean response time, frequency of exceeding some deadlines, etc). The 
quality of a soft real time system is usually judged by non-DAQ criteria (i.e. if the DAQ for the T2K/ND280 
experiment does not respond within 20 msec, a neutrino beam spill an be lost and the experiment is 
required to report the number of lost spills to the weekly facility management meeting).

Can the trigger latency be improved by using interrupts instead of polling? Remember that on most 
hardware, the VME and PCI bus access time is around 1 usec and trigger latency of 5-10 usec corresponds 
to roughly 5-10 reads of a PCI or VME register. So there is not much room for speed up. Consider that an 
interrupt handler has to perform at least 2-3 PCI register reads (to determine the source of the interrupt 
and to clear the interrupt condition), it has to wake up the right process and do a rather slow CPU context 
switch, maybe do a cross-CPU interrupt (if VME interrupts are routed to the wrong CPU core). All this 
takes time. Then the Linux kernel interrupt latency comes into play. All this is overhead absent in pure-
polling implementations. (Yes, burning a CPU core to poll for data is wasteful, but is there any other use 
for this CPU core? With a dual-core CPU, the 1st core polls for data, the 2nd core runs mfe.c, the TCP/IP 
stack and the ethernet transmitter.)

2) "readout time" - between 7 and 8 msec, corresponding to the 50 Mbytes/sec VME block transfer rate. 
No events taking more than 10 msec. (Could claim hard real time performance here).

3) "busy time" - for the simple benchmark system it is a boring sum of plots (1) and (2). The mean busy 
time ("dead time") goes straight into the formula for computing cross-sections (if that is what you do).

4) "time between events" - provides an independent measurement of dead time - one can see that no 
event takes less than 7 msec to process and 27 events took longer than 10 msec (0.65% out of 4154 
events). If the trigger were cosmic rays instead of a pulser, this plot would also measure the cosmic ray 
event rate - one would see the exponential shape of the Poisson distribution (linear on Log scale, with the 
slope being the cosmic event rate).


K.O.
Attachment 1: canvas.pdf
canvas.pdf
  817   26 Jun 2012 Konstantin OlchanskiInfomidas vme benchmarks
> > > > I am recording here the results from a test VME system using four VF48 
waveform digitizers

Last message from this series. After all the tuning, I reduce the trigger rate 
from 120 Hz to 100 Hz to see
what happens when the backend computer is not overloaded and has some spare 
capacity.

event rate: 100 Hz (down from 120 Hz)
data rate: 37 Mbytes/sec (down from 50 M/s)
mlogger cpu use: 65% (down from 99%)

Attached:

1) trigger rate event plot: now the rate is solid 100 Hz without dropouts
2) CPU and Network plots frog ganglia: the spikes is lazylogger saving mid.gz 
files to HDFS storage
3) time structure plots:
a) trigger latency: mean 5 us, most below 10 us, 59 events (0.046%) longer than 
100 us, (bottom left graph) 7000 us is longest latency observed.
b) readout time is 7000-8000 us (same as before - VME data rate is independant 
from the trigger rate)
c) busy time: mean 7.2 us, 12 events (0.0094%) longer than 10 ms, longest busy 
time ever observed is 17 ms (bottom middle graph)
d) time between events is 10 ms (100 Hz pulser trigger), 1 event was missed 
about 10 times (spike at 20 ms) (0.0085%), more than 1 event missed never (no 
spike at 30 ms, 40 ms, etc).


CPU use on the backend computer:

top - 16:30:59 up 75 days, 35 min,  6 users,  load average: 0.98, 0.99, 1.01
Tasks: 206 total,   3 running, 203 sleeping,   0 stopped,   0 zombie
Cpu(s): 39.3%us,  8.2%sy,  0.0%ni, 39.4%id,  5.7%wa,  0.3%hi,  7.2%si,  0.0%st
Mem:   3925556k total,  3404192k used,   521364k free,     8792k buffers
Swap: 32766900k total,   296304k used, 32470596k free,  2477268k cached

  PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND            
 5826 trinat    20   0  441m 292m 287m R 65.8  7.6   2215:16 mlogger            
26756 trinat    20   0  310m 288m 288m S 16.8  7.5  34:32.03 mserver            
29005 olchansk  20   0  206m  39m  17m R 14.7  1.0  26:19.42 ana_vf48.exe       
 7878 olchansk  20   0   99m 3988  740 S  7.7  0.1  27:06.34 sshd               
29012 trinat    20   0  314m 288m 288m S  2.8  7.5   4:22.14 mserver            
23317 root      20   0     0    0    0 S  1.4  0.0  24:21.52 flush-9:3     


K.O.
Attachment 1: Scalers.gif
Scalers.gif
Attachment 2: ladd02-cpu.png
ladd02-cpu.png
Attachment 3: ladd02-net.png
ladd02-net.png
Attachment 4: canvas-1000-100Hz.pdf
canvas-1000-100Hz.pdf
  2583   16 Aug 2023 Konstantin OlchanskiBug Reportmidas wants to show notification?
I started to get web browser popups about "midas wants to show notifications, 
block/allow/x". is this a glitch or a new unannounced/undocumented feature? 
google chrome on macos. K.O.
ELOG V3.1.4-2e1708b5