> > for correct operation of bm_send_event() under all conditions we need to ...
> to continue computation from last message:
if I got my numbers right, for present-day hardware (1gige/10gige data rates, 100 Hz max locking rate), we should
increase the default buffer write cache size from 100 kbytes to 10 Mbytes.
this cache size will permit processing of the full mix of small/big events
at the full mix of event rates without exceeding the 100 Hz semaphore locking rate.
with the 10 Mbyte write cache, default event buffer size should be 30-40 Mbytes (current size is 33 Mbytes, so does
not need to change).
this computation is for 1 writer (1 reader, mlogger). it is a typical case for our experiments.
multiple writers can run into contention for event buffer space.
consider 10 writers want to flush their 10 Mbyte write cache all at the same time:
if buffer size is the default 33 Mbytes, the first 3 writers will have successful write cache flush,
but the other 7 will stall, there is no space in the buffer, we have to wait for mlogger to free
some (mlogger writing X Mbytes/sec will take Y milliseconds to liberate 10 Mbytes of space for the 4th writer
to successfully flush, writers 5..10 are still stalled).
but in a system with 10 writers writing at 10 Mbytes/sec (1 Hz default cache flush rate) is 100 Mbytes/sec
will likely have SYSTEM buffer size at least 200-300 Mbytes (to buffer 1-2 seconds of data against
any delays in writing to disk/network storage).
so there should be no problem in practice.