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Date:      Thu, 6 Apr 2006 03:39:30 +0300
From:      Sven Petai <hadara@bsd.ee>
To:        freebsd-performance@freebsd.org
Cc:        Mike Silbersack <silby@silby.com>
Subject:   Re: mysql tests - one more thing to try
Message-ID:  <200604060339.31800.hadara@bsd.ee>
In-Reply-To: <20060405134919.T16926@odysseus.silby.com>
References:  <20060405134919.T16926@odysseus.silby.com>

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On Wednesday 05 April 2006 21:52, Mike Silbersack wrote:

> If you're willing to spend more time looking at this, I suggest that you
> run truss or ktrace on the super-smack processes.  I did a small amount of
> mysql vs postgres vs firebird benchmarking two years ago for a class
> project, and noticed that mysql's results were showing the same phenomena
> - our test program was using more cpu than mysqld.  I run truss on our
> test program and found that it was doing ONE BYTE READS from the socket,
> rather than something larger.
>
> I never had the time to see if the problem was fixed at a later time or
> not.  You may wish to see if that same condition is still happening.

here are ktrace results for supersmack and mysqld from a dualcore opteron box 
running select smack with 100 threads and 10000 queries
os: fbsd 6.1 prerelease

==== syscall stats for supersmack ====
number of syscalls captured:  42575687
individual syscalls counts:
   read   32914539  77.31%
   gettimeofday   3865508  9.08%
   fcntl   3862708  9.07%
   write   1930922  4.54%
   break   325  0.00%
   close   301  0.00%
   setsockopt   202  0.00%
   select   192  0.00%
   semop   184  0.00%
   connect   101  0.00%
   wait4   101  0.00%
   socket   101  0.00%
   getpid   100  0.00%
   fork   100  0.00%
   exit   97  0.00%
   shutdown   96  0.00%
   mmap   27  0.00%
   access   15  0.00%
   mprotect   12  0.00%
   open   12  0.00%
   fstat   10  0.00%
   munmap   8  0.00%
   execve   7  0.00%
   ioctl   4  0.00%
   stat   3  0.00%
   sigprocmask   2  0.00%
   issetugid   2  0.00%
   lseek   1  0.00%
   sysarch   1  0.00%
   __sysctl   1  0.00%
   semget   1  0.00%
   readlink   1  0.00%
   sigaction   1  0.00%
   pipe   1  0.00%
   __semctl   1  0.00%

request sizes for syscall read
  size  count   %
---------------------------
   4    15489977  47.06%
   50    3982797  12.10%
   1    3873493  11.77%
   52    2654645  8.07%
   60    1937753  5.89%
   5    1933249  5.87%
   8192    1931176  5.87%
   53    790179  2.40%
   51    274285  0.83%
   49    23467  0.07%
   48    12943  0.04%
   1023    5301  0.02%
   47    2543  0.01%
   46    2497  0.01%
   7    101  0.00%
   24    99  0.00%
   4096    29  0.00%
   128    1  0.00%
   6    1  0.00%
   17796    1  0.00%
   30    1  0.00%
   66    1  0.00%

request sizes for syscall write
  size  count   %
---------------------------
   65    1716567  88.90%
   64    193387  10.02%
   63    20584  1.07%
   47    101  0.01%
   5    94  0.00%
   4    92  0.00%
   26    92  0.00%
   34    1  0.00%
   35    1  0.00%
   40    1  0.00%
   49    1  0.00%
   55    1  0.00%

==== syscall stats for mysqld ====

number of syscalls captured:  20743045
individual syscalls counts:
   _umtx_op   7657825  36.92%
   gettimeofday   4308736  20.77%
   read   4306035  20.76%
   write   1942882  9.37%
   sigprocmask   1680724  8.10%
   fcntl   838247  4.04%
   thr_kill   2827  0.01%
   sigwait   2403  0.01%
   setitimer   1669  0.01%
   select   698  0.00%
   setsockopt   202  0.00%
   access   101  0.00%
   accept   101  0.00%
   getsockname   101  0.00%
   open   101  0.00%
   shutdown   96  0.00%
   close   96  0.00%
   thr_new   92  0.00%
   thr_exit   87  0.00%
   break   22  0.00%

request sizes for syscall write
  size  count   %
---------------------------
   304    794935  40.92%
   303    720255  37.07%
   302    274534  14.13%
   301    111278  5.73%
   300    23412  1.21%
   299    13079  0.67%
   297    2615  0.13%
   298    2571  0.13%
   11    101  0.01%
   56    101  0.01%
   63    1  0.00%
request sizes for syscall read
  size  count   %
---------------------------
   4    2362079  54.86%
   61    1728044  40.13%
   60    194721  4.52%
   59    20993  0.49%
   43    101  0.00%
   1    96  0.00%
   31    1  0.00%



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