Good tips. I have been testing the performance difference of
system-calls, library routines, ipc implementations between Solaris
and Linux. This is one of the test codes I quickly put together to
show the difference. I'll keep your options on the table and suggest
soon as we get to this point.

many thanks.

senthil

On 7/1/08, [EMAIL PROTECTED] <[EMAIL PROTECTED]> wrote:
> Your welcome.  If the value you are incrementing is unique to each thread
> you
>  can try forcing them onto their own cache line
>
>  int value[64];
>  #define VALUE_1   0
>  #define VALUE_2 16
>  #define VALUE_3 32
>  #define VALUE_4 48
>
>  Where value would be one location for the thread.  This will remove
> potential cache thrashing going on.
>  If  you are using one value then you could try placing them together on a
> cache line (take the single miss for the lock and update).
>
>  struct data {
>    mutex lock;
>    int count;
>    int pad_to_64[14];
>  };
>
>  There are games that you need to play with the compiler/loader to get these
> lined up on their own
>  cache line, what that game is depends on the code.
>
>  Dave V
>
>
>  senthil ramanujam wrote:
>
> > Hi Dave,
> >
> > hmmm, I was kind of expecting this answer. Thanks for your analysis.
> >
> > senthil
> >
> > On 7/1/08, [EMAIL PROTECTED] <[EMAIL PROTECTED]> wrote:
> >
> >
> > > Ok, this pretty much verifies what I thought.  In the short, by running
> > > truss you have
> > >  slowed things down enough in the application to significantly remove
> the
> > > lock contention
> > >  on the program's mutex.  This is one of those performance items that
> > > appears to be contradictory
> > >  on the surface.
> > >
> > >  A bit more on this now:
> > >
> > >  Your program has a very tight loop, you acquire the lock, increment a
> > > variable and drop the
> > >  lock.  There is a whole slew of atomic_* operations that essentially
> does
> > > the same thing, just
> > >  more efficient (if they can be used depends on the case).
> > >  By being a tight loop as it is, during the operation of the program
> without
> > > truss  it ends up having
> > >  the threads queuing up on each other in attempt to acquire the lock.
> When
> > > we miss on a lock because
> > >  it is owned by another thread we end up going into a totally different
> set
> > > of lock routines which is
> > >  expensive.  By running truss what you have done is slowed things down
> > > enough to reduce the
> > >  lock contention being seen on the mutex in your program and the
> likeliness
> > > of entering the "slow" lock
> > >  path.  If you were to add work before or after the mutex operation you
> will
> > > see the same effect, and probably
> > >  even to a greater degree.
> > >  Hope this helps.
> > >
> > >
> > >  Dave Valin
> > >
> > >  senthil ramanujam wrote:
> > >
> > >
> > >
> > > > Hi Dave,
> > > >
> > > > Here is the plockstat data for both the cases. Let me know if you like
> > > > to see more details.
> > > >
> > > > Looking forward to hear your comments.
> > > >
> > > > thanks.
> > > >
> > > > senthil
> > > >
> > > >
> > > > $ plockstat -A mutex_ops -w4 -r10
> > > >  number of threads:4,   run-time (in seconds)=10
> > > >  Thread    2:   total ops: 456161,   ops/second:    45616
> > > >  Thread    0:   total ops: 452104,   ops/second:    45210
> > > >  Thread    1:   total ops: 167338,   ops/second:    16733
> > > >  Thread    3:   total ops: 174826,   ops/second:    17482
> > > > plockstat: pid 13497 has exited
> > > >
> > > > Mutex hold
> > > >
> > > > Count     nsec Lock                         Caller
> > > >
> > > >
> > > >
> > >
> -------------------------------------------------------------------------------
> > >
> > >
> > > > 1248577     1639 mutex_ops`worker_mutex       mutex_ops`do_run+0x1b2
> > > >  1851     1960 mutex_ops`worker_mutex       mutex_ops`do_run+0x1b2
> > > >   3   104789 mutex_ops`_iob+0xa8          mutex_ops`do_run+0x25a
> > > >   1    82008 libc.so.1`_uberdata+0xfc0    0x400e16
> > > >   1    42599 libc.so.1`_first_link_lock   libc.so.1`_exithandle+0x3b
> > > >   1    39967 libc.so.1`_uberdata+0x60     LM1`ld.so.1`rt_thr_init+0x29
> > > >   4     9374 libc.so.1`_uberdata+0x1040   libc.so.1`_lwp_start
> > > >   4     8402 libc.so.1`_uberdata+0x40
> libc.so.1`pthread_create+0x135
> > > >   1    32844 mutex_ops`_iob+0x28          libc.so.1`_exithandle+0x3b
> > > >   3     9736 libc.so.1`_uberdata
> > > >
> > > >
> > > libc.so.1`_thr_exit_common+0x9c
> > >
> > >
> > > >   4     6343 libc.so.1`_uberdata          mutex_ops`main+0x2e7
> > > >   1    25319 mutex_ops`_iob+0xa8          mutex_ops`do_run+0x25a
> > > >   4     6162 libc.so.1`_uberdata          mutex_ops`main+0x22e
> > > >   4     4369 libc.so.1`_uberdata
> > > >
> > > >
> > > libc.so.1`_thr_exit_common+0x9c
> > >
> > >
> > > >   2     6982 mutex_ops`worker_mutex       mutex_ops`do_run+0xea
> > > >   6     1524 libc.so.1`_uberdata+0xd40    libc.so.1`exit+0x11
> > > >   1     8422 libc.so.1`_uberdata
> > > >
> > > >
> > > libc.so.1`_thr_exit_common+0x9c
> > >
> > >
> > > >   4     1934 libc.so.1`_uberdata+0x1040   libc.so.1`_thrp_unwind+0x5e
> > > >   1     7646 0xfffffd7fff220100
> libc.so.1`_thr_exit_common+0x9c
> > > >   2     3517 mutex_ops`worker_mutex       mutex_ops`do_run+0xea
> > > >   1     6603 libc.so.1`_uberdata+0xd40    libc.so.1`libc_init+0x2c6
> > > >   4     1516 libc.so.1`_uberdata+0x1000   libc.so.1`_thrp_unwind+0x5e
> > > >   1     6029 0xfffffd7fff220080
> libc.so.1`pthread_create+0x135
> > > >   1     5789 0xfffffd7fff220080
> libc.so.1`_thr_exit_common+0x9c
> > > >   1     4387 0xfffffd7fff2200c0
> libc.so.1`pthread_create+0x135
> > > >   3     1447 libc.so.1`_uberdata+0xe80    libc.so.1`find_stack+0x18a
> > > >   3     1396 libc.so.1`_uberdata          libc.so.1`_thrp_create+0x531
> > > >   1     4078 0xfffffd7fff220100
> libc.so.1`pthread_create+0x135
> > > >   3     1309 libc.so.1`_uberdata
> libc.so.1`pthread_create+0xfe
> > > >   1     3900 0xfffffd7fff220140
> libc.so.1`pthread_create+0x135
> > > >   1     3811 0xfffffd7fff2200c0
> libc.so.1`_thr_exit_common+0x9c
> > > >   1     3436 0xfffffd7fff220140
> libc.so.1`_thr_exit_common+0x9c
> > > >   1     2827 0xfffffd7fff220080
> libc.so.1`pthread_create+0xfe
> > > >   2     1367 libc.so.1`_uberdata+0xe40    libc.so.1`_thrp_unwind+0x5e
> > > >   1     2369 libc.so.1`_uberdata+0xd40    libc.so.1`_thrp_create+0x370
> > > >   1     2341 mutex_ops`worker_mutex       mutex_ops`do_run+0x1b2
> > > >   1     2311 libc.so.1`_uberdata+0x1040   LM1`ld.so.1`rt_thr_init+0x29
> > > >   1     2056 0xfffffd7fff220100           mutex_ops`main+0x2e7
> > > >   1     1951 0xfffffd7fff2200c0           mutex_ops`main+0x2e7
> > > >   1     1863 0xfffffd7fff220140           mutex_ops`main+0x2e7
> > > >   1     1803 0xfffffd7fff220140
> libc.so.1`pthread_create+0xfe
> > > >   1     1794 libc.so.1`_uberdata          mutex_ops`main+0x22e
> > > >   1     1782 0xfffffd7fff220100
> libc.so.1`pthread_create+0xfe
> > > >   1     1671 0xfffffd7fff2200c0
> libc.so.1`pthread_create+0xfe
> > > >   1     1622 mutex_ops`_iob+0xa8          libc.so.1`_exithandle+0x3b
> > > >   1     1510 0xfffffd7fff220080           mutex_ops`main+0x2e7
> > > >   1     1508 libc.so.1`_uberdata+0xe80    libc.so.1`_thrp_create+0x531
> > > >   1     1506 libc.so.1`_uberdata+0xd40    0x400dbb
> > > >   1     1495 libc.so.1`_uberdata+0xfc0    0x400dbb
> > > >   1     1446 libc.so.1`_uberdata+0xfc0
> libc.so.1`pthread_create+0xfe
> > > >   1     1398 libc.so.1`_uberdata+0xd40    libc.so.1`_thrp_create+0x370
> > > >   1     1389 libc.so.1`_uberdata
> libc.so.1`pthread_create+0xfe
> > > >   1     1370 libc.so.1`_uberdata+0xfc0
> libc.so.1`pthread_create+0xfe
> > > >   1     1347 libc.so.1`_uberdata+0xd40    0x400dc7
> > > >   1     1310 libc.so.1`_uberdata+0xfc0    0x400dc7
> > > >   1     1194 libc.so.1`_uberdata+0xfc0
> libc.so.1`pthread_create+0xfe
> > > >   1     1177 libc.so.1`_uberdata+0xd40    libc.so.1`_thrp_create+0x370
> > > >
> > > > Mutex block
> > > >
> > > > Count     nsec Lock                         Caller
> > > >
> > > >
> > > >
> > >
> -------------------------------------------------------------------------------
> > >
> > >
> > > >  866 21921703 mutex_ops`worker_mutex       mutex_ops`do_run+0x150
> > > > 692495     8328 mutex_ops`worker_mutex       mutex_ops`do_run+0x150
> > > >   2 11086954 mutex_ops`worker_mutex       mutex_ops`do_run+0x94
> > > >   3   219879 mutex_ops`_iob+0xa8          libc.so.1`_flockget+0x1a
> > > >   1    12013 libc.so.1`_uberdata          mutex_ops`main+0x2e7
> > > >   1     2094 libc.so.1`_uberdata
> > > >
> > > >
> > > libc.so.1`_thr_exit_common+0x9c
> > >
> > >
> > > > << trusss + mutex >>
> > > > $ plockstat -A truss -fc mutex_ops -w4 -r10
> > > >  number of threads:4,   run-time (in seconds)=10
> > > >  Thread    2:   total ops: 17918909,   ops/second:  1791890
> > > >  Thread    0:   total ops: 18518051,   ops/second:  1851805
> > > >  Thread    1:   total ops: 18280090,   ops/second:  1828009
> > > >  Thread    3:   total ops: 18889775,   ops/second:  1888977
> > > >
> > > > syscall               seconds   calls  errors
> > > > _exit                    .000       1
> > > > write                    .000       5
> > > > open                     .000       3       1
> > > > close                    .000       2
> > > > stat                     .000      10       7
> > > > getpid                   .000       1
> > > > fstat                    .000       1
> > > > ioctl                    .000       1
> > > > execve                   .000       1
> > > > lwp_park                 .634   94191
> > > > lwp_unpark               .501   94191
> > > > sigaction                .000       1
> > > > getcontext               .000       1
> > > > setustack                .000       5
> > > > mmap                     .000      16
> > > > munmap                   .000       2
> > > > getrlimit                .000       1
> > > > memcntl                  .000       1
> > > > sysconfig                .000       2
> > > > yield                    .082   12845
> > > > lwp_create               .000       4
> > > > lwp_exit                 .000       4
> > > > lwp_continue             .000       4
> > > > lwp_sigmask              .000       4
> > > > lwp_private              .000       1
> > > > lwp_wait                 .000       4
> > > > lwp_mutex_wakeup         .000      10
> > > > nanosleep                .000       1
> > > > schedctl                 .000       5
> > > > resolvepath              .000       4
> > > > lwp_mutex_timedlock      .000      68
> > > > getcwd                   .000       1
> > > >                    --------  ------   ----
> > > > sys totals:             1.219  201391      8
> > > > usr time:              17.809
> > > > elapsed:               10.030
> > > > plockstat: pid 13499 has exited
> > > >
> > > > Mutex hold
> > > >
> > > > Count     nsec Lock                         Caller
> > > >
> > > >
> > > >
> > >
> -------------------------------------------------------------------------------
> > >
> > >
> > > > 257123     8166 truss`truss_lock             truss`worker_thread+0x3a7
> > > > 145651    11250 truss`truss_lock             truss`worker_thread+0x3a7
> > > > 201384     1893 truss`count_lock             truss`sysexit+0x82d
> > > >   1  2468522 libc.so.1`_uberdata+0x60     libproc.so.1`Pxcreate+0x63
> > > >   1  2447046 libnsl.so.1`_ti_userlock
> > > > libnsl.so.1`_libnsl_parent_atfork+0x10
> > > >   1  2380540 libc.so.1`_uberdata+0xfc0    libc.so.1`fork+0x130
> > > >   1  2364179 libc.so.1`_first_link_lock   libc.so.1`fork+0x130
> > > >   1  2356270 libc.so.1`libc_malloc_lock   libc.so.1`fork+0x130
> > > >   1  2337553 libc.so.1`_uberdata+0x40     libproc.so.1`Pxcreate+0x63
> > > >   4    52074 0x455478                     libproc.so.1`Lgrab+0x234
> > > >   1   144394 libc.so.1`_uberdata+0xfc0    truss`main_thread+0x1e8
> > > >   4    32702 truss`truss_lock             truss`worker_thread+0x5d6
> > > >   5    23212 0x455478                     libproc.so.1`Lfree+0x3a
> > > >   1    66469 0xfef9e1b0                   0xfef06df3
> > > >   1    64668 0xfefa12c0                   0xfef67a91
> > > >  32     1858 truss`_iob+0xa8              truss`report+0x223
> > > >   1    58652 0x455478                     libproc.so.1`Lgrab+0x234
> > > >   5    11034 libc.so.1`_uberdata
> > > >
> > > >
> > > libc.so.1`_thr_exit_common+0x9c
> > >
> > >
> > > >  32     1583 truss`_iob+0xa8              truss`prtim+0x51
> > > >  32     1547 truss`_iob+0xa8              truss`report+0x25e
> > > >   2    23108 libc.so.1`libc_malloc_lock   truss`my_realloc+0x18
> > > >  32     1412 truss`_iob+0xa8              truss`prtim+0x64
> > > >   1    40708 0xfefa12a0                   0xfef021df
> > > >   1    40112 libc.so.1`_uberdata+0x60     LM1`ld.so.1`rt_thr_init+0x29
> > > >   1    34837 libc.so.1`_first_link_lock   libc.so.1`_exithandle+0x3b
> > > >   5     6891 truss`truss_lock             truss`main_thread+0x116
> > > >   1    34270 0xfef9e5d0                   0xfef14052
> > > >   4     8244 libc.so.1`_uberdata+0x40     truss`worker_thread+0xe52
> > > >   1    31319 libc.so.1`libc_malloc_lock   truss`my_realloc+0x18
> > > >   5     6235 libc.so.1`_uberdata          truss`main_thread+0x125
> > > >   4     7557 libc.so.1`libc_malloc_lock   libproc.so.1`Lgrab+0xd3
> > > >   5     6010 libc.so.1`_uberdata+0x1040   libc.so.1`_lwp_start
> > > >   1    29687 libc.so.1`libc_malloc_lock   truss`main+0x4ac
> > > >   1    28272 libc.so.1`mktemp_lock.0      truss`main+0xdb4
> > > >   1    26436 truss`truss_lock             truss`worker_thread+0x5d6
> > > >   1    25322 truss`_iob+0xa8              libc.so.1`_exithandle+0x3b
> > > >   1    25197 libc.so.1`libc_malloc_lock   truss`my_realloc+0x18
> > > >   4     6142 libc.so.1`_uberdata          truss`worker_thread+0xe34
> > > >   1    21847 libc.so.1`libc_malloc_lock   truss`my_calloc+0x18
> > > >   1    19740 libproc.so.1`minfd_lock.0    libproc.so.1`set_minfd+0x46
> > > >   1    17725 0xfffffd7fff060140
> libc.so.1`_thr_exit_common+0x9c
> > > >   1    14834 libc.so.1`libc_malloc_lock   truss`free_private+0x44
> > > >   5     2865 libc.so.1`libc_malloc_lock   truss`my_realloc+0x18
> > > >   1    12900 0xfffffd7fff200080           truss`Xcritical+0x46
> > > >   5     2470 libc.so.1`_uberdata
> > > >
> > > >
> > > libc.so.1`_thr_exit_common+0x9c
> > >
> > >
> > > >   1    12239 libc.so.1`__sbrk_lock
> > > >
> > > >
> > > libc.so.1`_malloc_unlocked+0x10d
> > >
> > >
> > > >   1    12155 0xfef9e1f0                   0xfef0703b
> > > >   1    12062 libc.so.1`libc_malloc_lock   truss`my_realloc+0x18
> > > >   6     2004 truss`count_lock             truss`worker_thread+0x108a
> > > >   1    11918 libc.so.1`_uberdata+0x40     truss`main_thread+0x1ed
> > > >   5     2347 truss`count_lock             truss`worker_thread+0xb09
> > > >   1    11608 0xfef9f708                   0xfef26ac9
> > > >   5     2215 libc.so.1`libc_malloc_lock
> > > >
> > > >
> > > libproc.so.1`Lfree_internal+0x67
> > >
> > >
> > > >   1    10685 libc.so.1`update_lock
> libctf.so.1`_libctf_init+0x10
> > > >   1    10092 libc.so.1`_uberdata          libproc.so.1`Pxcreate+0x63
> > > >   5     2016 libc.so.1`_uberdata+0x1040   libc.so.1`_thrp_unwind+0x5e
> > > >   1     9656 0x455478                     libproc.so.1`Pfree+0x117
> > > >   2     4810 libc.so.1`__sbrk_lock        libc.so.1`realloc+0x235
> > > >   5     1871 0xfffffd7fff200080           truss`Xcritical+0x46
> > > >   6     1543 libc.so.1`_uberdata+0xd40    libc.so.1`exit+0x11
> > > >   5     1744 libc.so.1`libc_malloc_lock   truss`free_private+0x55
> > > >   5     1738 libc.so.1`_uberdata+0x1000   libc.so.1`_thrp_unwind+0x5e
> > > >   5     1688 libc.so.1`libc_malloc_lock   truss`free_private+0x66
> > > >   1     8407 truss`count_lock             truss`setup_basetime+0x60
> > > >   1     8252 libc.so.1`libc_malloc_lock   truss`my_realloc+0x18
> > > >   2     4044 libc.so.1`__sbrk_lock        libc.so.1`malloc+0x2d
> > > >   1     8072 libc.so.1`libc_malloc_lock   libproc.so.1`Lgrab+0x72
> > > >   5     1612 libc.so.1`_uberdata+0x1000   libc.so.1`_thrp_unwind+0x5e
> > > >   1     8046 libc.so.1`libc_malloc_lock   truss`my_realloc+0x18
> > > >   5     1543 libc.so.1`libc_malloc_lock   truss`my_realloc+0x18
> > > >   2     3818 libc.so.1`__sbrk_lock        libc.so.1`realloc+0x235
> > > >   4     1897 libc.so.1`_uberdata          libc.so.1`thr_create+0x3f
> > > >   1     7516 0xfef9e5d0                   0xfef14052
> > > >   5     1497 libc.so.1`libc_malloc_lock   truss`my_realloc+0x18
> > > >   1     7375 0xfffffd7fff060080           truss`main_thread+0x1ed
> > > >   1     7372 libc.so.1`_uberdata          truss`create_thread+0x58
> > > >   1     6977 libc.so.1`_uberdata+0xd40    libc.so.1`libc_init+0x2c6
> > > >   1     6664 0xfefa1f80                   0xfef63d56
> > > >   4     1663 libc.so.1`_uberdata+0xe80    libc.so.1`find_stack+0x18a
> > > >   1     6569 0xfffffd7fff060180
> libc.so.1`_thr_exit_common+0x9c
> > > >   2     3186 libc.so.1`__sbrk_lock        libc.so.1`malloc+0x2d
> > > >   1     6260 libc.so.1`_uberdata+0x1000   truss`main+0xf8
> > > >   1     5847 libc.so.1`libc_malloc_lock   libproc.so.1`Lgrab+0xd3
> > > >   1     5799 libc.so.1`_uberdata+0x60
> > > >
> > > >
> > > libnsl.so.1`_libnsl_lock_init+0x86
> > >
> > >
> > > >   1     5664 0xfffffd7fff060140           truss`worker_thread+0xe52
> > > >   1     5502 0xfefa2240                   0xfef734b2
> > > >   4     1338 libc.so.1`_uberdata          libc.so.1`_thrp_create+0x531
> > > >   1     5248 0xfffffd7fff0600c0           truss`worker_thread+0xe52
> > > >   1     5204 libc.so.1`__sbrk_lock
> > > >
> > > >
> > > libc.so.1`_malloc_unlocked+0x10d
> > >
> > >
> > > >   1     5141 truss`count_lock             truss`per_proc_init+0xe1
> > > >   1     5105 0xfefa10e0                   0xfef62237
> > > >   1     4904 0xfefa10e0                   0xfef62237
> > > >   3     1613 libc.so.1`libc_malloc_lock   truss`free_private+0x44
> > > >   1     4403 libc.so.1`_uberdata+0x140    truss`main+0xbeb
> > > >   1     4245 0xfffffd7fff060100           truss`worker_thread+0xe52
> > > >   1     3702 0xfffffd7fff0600c0
> libc.so.1`_thr_exit_common+0x9c
> > > >   1     3469 truss`_iob+0xa8              truss`report+0x418
> > > >   2     1702 libc.so.1`libc_malloc_lock   truss`my_realloc+0x18
> > > >   1     3396 0xfffffd7fff060100
> libc.so.1`_thr_exit_common+0x9c
> > > >   2     1641 libc.so.1`_uberdata+0xe40    libc.so.1`_thrp_unwind+0x5e
> > > >   2     1514 truss`_iob+0xa8              truss`report+0x366
> > > >   2     1477 libc.so.1`libc_malloc_lock   truss`my_realloc+0x18
> > > >   2     1369 libc.so.1`libc_malloc_lock   truss`sysentry+0x4e7
> > > >   1     2653 0xfffffd7fff060080           libc.so.1`thr_create+0x3f
> > > >   1     2646 libc.so.1`_uberdata+0x140    truss`main+0xbff
> > > >   1     2528 truss`truss_lock             truss`main_thread+0x116
> > > >   1     2470 libc.so.1`_uberdata+0x580    truss`main+0x554
> > > >   1     2452 0xfffffd7fff200080           truss`Xcritical+0x46
> > > >   1     2391 0xfffffd7fff060080
> libc.so.1`_thr_exit_common+0x9c
> > > >   1     2223 libc.so.1`_uberdata+0x440    truss`main+0x545
> > > >   1     2219 libc.so.1`libc_malloc_lock   truss`my_realloc+0x18
> > > >   1     2203 libc.so.1`_uberdata+0x4c0    truss`main+0x518
> > > >   1     2187 libc.so.1`_uberdata+0x500    truss`main+0x527
> > > >   1     2185 libc.so.1`_uberdata+0xd40    libc.so.1`_thrp_create+0x370
> > > >   1     2182 0xfefa2280                   0xfef73271
> > > >   1     2127 0xfffffd7fff060080           truss`main_thread+0x125
> > > >   1     2113 0xfffffd7fff060180           truss`worker_thread+0xe52
> > > >   1     2090 libc.so.1`_uberdata+0x1040   LM1`ld.so.1`rt_thr_init+0x29
> > > >   1     2082 libc.so.1`libc_malloc_lock   truss`my_realloc+0x18
> > > >   1     2072 libc.so.1`_uberdata+0x540    truss`main+0x536
> > > >   1     2057 libc.so.1`_uberdata+0x180    truss`main+0xc0e
> > > >   1     2041 libc.so.1`_uberdata+0x1c0    truss`main+0xc31
> > > >   1     2035 0xfffffd7fff060140           truss`main_thread+0x125
> > > >   1     2013 0xfffffd7fff060140           libc.so.1`thr_create+0x3f
> > > >   1     1968 libc.so.1`libc_malloc_lock   truss`main+0xdf1
> > > >   1     1961 0xfefa2000                   0xfef63d56
> > > >   1     1954 libc.so.1`_uberdata          libproc.so.1`Pxcreate+0x63
> > > >   1     1927 0xfffffd7fff0600c0           truss`main_thread+0x125
> > > >   1     1923 libc.so.1`_uberdata+0x180    truss`main+0xc22
> > > >   1     1918 0xfffffd7fff060100           libc.so.1`thr_create+0x3f
> > > >   1     1917 truss`_iob+0xa8              truss`prtim+0x20
> > > >   1     1891 0xfffffd7fff060180           truss`main_thread+0x125
> > > >   1     1890 libc.so.1`_uberdata+0x1c0    truss`main+0x507
> > > >   1     1884 libc.so.1`seed_lk            truss`main+0xdb4
> > > >   1     1877 libc.so.1`libc_malloc_lock   libproc.so.1`Pfree+0x10f
> > > >   1     1875 libc.so.1`libc_malloc_lock   libproc.so.1`Pxcreate+0x52
> > > >   1     1867 libc.so.1`libc_malloc_lock   truss`main+0xdb4
> > > >   1     1832 0xfffffd7fff0600c0           libc.so.1`thr_create+0x3f
> > > >   1     1830 0xfffffd7fff060100           truss`main_thread+0x125
> > > >   1     1770 libc.so.1`_uberdata+0xfc0    libc.so.1`thr_create+0x3f
> > > >   1     1765 libc.so.1`libc_malloc_lock   truss`my_realloc+0x18
> > > >   1     1754 truss`_iob+0x28              libc.so.1`_exithandle+0x3b
> > > >   1     1732 libc.so.1`_uberdata+0xd40    truss`main+0xf8
> > > >   1     1723 libc.so.1`_uberdata+0xd40    truss`_start+0x1b
> > > >   1     1695 truss`_iob+0xa8              truss`report+0x4af
> > > >   1     1681 libc.so.1`_uberdata+0xd40
> > > >
> > > >
> > > libnsl.so.1`_libnsl_lock_init+0x86
> > >
> > >
> > > >   1     1674 libc.so.1`_uberdata+0xe80    libc.so.1`_thrp_create+0x531
> > > >   1     1649 0xfefa1f80                   0xfef63d56
> > > >   1     1648 truss`_iob+0xa8              truss`report+0x492
> > > >   1     1647 0xfef9e5d0                   0xfef14052
> > > >   1     1642 0xfffffd7fff200080           truss`Xcritical+0x46
> > > >   1     1640 truss`_iob+0xa8              truss`report+0x486
> > > >   1     1637 truss`_iob+0xa8              truss`prtim+0x20
> > > >   1     1624 0xfffffd7fff060180           libc.so.1`thr_create+0x3f
> > > >   1     1616 0xfefa2200                   0xfef01d17
> > > >   1     1608 libc.so.1`_uberdata          truss`create_thread+0x58
> > > >   1     1608 truss`_iob+0xa8              truss`prtim+0x51
> > > >   1     1547 truss`_iob+0xa8              truss`report+0x53e
> > > >   1     1547 truss`_iob+0xa8              truss`prtim+0x51
> > > >   1     1533 0xfefa2040                   0xfef63d56
> > > >   1     1518 0xfefa1f80                   0xfef63d56
> > > >   1     1505 libc.so.1`libc_malloc_lock   libproc.so.1`Pfree+0x1cf
> > > >   1     1488 0xfefa1f80                   0xfef63d56
> > > >   1     1466 truss`_iob+0xa8              truss`prtim+0x51
> > > >   1     1445 libc.so.1`libc_malloc_lock   truss`free_private+0x88
> > > >   1     1443 libc.so.1`libc_malloc_lock   truss`my_realloc+0x18
> > > >   1     1426 truss`_iob+0xa8              truss`report+0x4cb
> > > >   1     1424 truss`_iob+0xa8              truss`prtim+0x20
> > > >   1     1415 0xfef9e5d0                   0xfef14052
> > > >   1     1404 libc.so.1`_uberdata+0xfc0    libc.so.1`thr_create+0x3f
> > > >   1     1397 libc.so.1`_uberdata+0xd40    libc.so.1`_thrp_create+0x370
> > > >   1     1378 libc.so.1`_uberdata+0xd40    libc.so.1`_thrp_create+0x370
> > > >   1     1372 libc.so.1`_uberdata          libc.so.1`thr_create+0x3f
> > > >   1     1363 libc.so.1`libc_malloc_lock   truss`free_private+0x90
> > > >   1     1345 libc.so.1`_uberdata+0xd40    truss`_start+0x27
> > > >   1     1343 0xfefa1f80                   0xfef63d56
> > > >   1     1341 libc.so.1`_uberdata+0xfc0    truss`_start+0x1b
> > > >   1     1340 0xfefa2200                   0xfef01d17
> > > >   1     1324 0xfefa1f80                   0xfef63d56
> > > >   1     1284 libc.so.1`_uberdata+0xfc0    libc.so.1`thr_create+0x3f
> > > >   1     1142 libc.so.1`_uberdata+0xfc0    truss`_start+0x27
> > > >
> > > > Mutex block
> > > >
> > > > Count     nsec Lock                         Caller
> > > >
> > > >
> > > >
> > >
> -------------------------------------------------------------------------------
> > >
> > >
> > > > 124379    34360 truss`truss_lock             truss`worker_thread+0x27d
> > > > 88153     2193 truss`truss_lock             truss`worker_thread+0x27d
> > > >   3    55924 truss`truss_lock             truss`worker_thread+0x5c4
> > > >   1    12080 libc.so.1`libc_malloc_lock   libc.so.1`free+0x18
> > > >   1     2286 truss`truss_lock             truss`main_thread+0xed
> > > > $
> > > >
> > > > On 7/1/08, [EMAIL PROTECTED] <[EMAIL PROTECTED]> wrote:
> > > >
> > > >
> > > >
> > > >
> > > > > Could you please provide lockstat information from plockstat for
> each of
> > > > > these
> > > > >  cases.  I think I know what you are seeing, but I want data to back
> up
> > > > >
> > > > >
> > > >
> > > the
> > >
> > >
> > > >
> > > > > theory.
> > > > >
> > > > >  Thanks
> > > > >
> > > > >  Dave Valin
> > > > >
> > > > >
> > > > >  senthil ramanujam wrote:
> > > > >
> > > > >
> > > > >
> > > > >
> > > > >
> > > > > > Hi,
> > > > > >
> > > > > > I am seeing a strange performance behavior with pthread mutex
> > > > > > operations on my Solaris (4-core) system running S10U5.
> > > > > >
> > > > > > The issue is that if the program is run with truss enabled, I am
> > > > > > getting about 3 times more the performance of the run without
> truss
> > > > > > enabled. Strange...right?
> > > > > >
> > > > > > The C program does the following:
> > > > > >  - accept 2 parameters [number of concurrent threads(N), and
> run-time]
> > > > > >  - create and run N threads simultaneously for <run-time> seconds
> > > > > >  - each thread does the following:
> > > > > >      - acquires the pthread mutex
> > > > > >      - increases the value of it's _own_ long variable by 1
> > > > > >      - releases the pthread mutex
> > > > > >  - after run-time expires, each thread reports the value of it's
> long
> > > > > >
> > > > > >
> > > > > >
> > > > > >
> > > > > variable
> > > > >
> > > > >
> > > > >
> > > > >
> > > > > > Note that I did not use any special flags to compile it. Reply
> back to
> > > > > > this email if you like to take a look at the program source code.
> > > > > >
> > > > > > Let's look at the program without truss enabled.
> > > > > >
> > > > > > $ mutex_ops -w4 -r10
> > > > > >  number of threads:4,   run-time (in seconds)=10
> > > > > >  Thread    1:   total ops: 4580775,   ops/second:   458077
> > > > > >  Thread    3:   total ops: 3798001,   ops/second:   379800
> > > > > >  Thread    0:   total ops: 4867850,   ops/second:   486785
> > > > > >  Thread    2:   total ops: 4925299,   ops/second:   492529
> > > > > > $
> > > > > > <<vmstat 1>>
> > > > > >  kthr      memory            page            disk          faults
> > > > > >
> > > > > >
> > > > >
> > > >
> > > cpu
> > >
> > >
> > > >
> > > > >
> > > > > >  r b w   swap  free  re  mf pi po fr de sr s0 s1 -- --   in   sy
> cs
> > > > > >
> > > > > >
> > > > >
> > > >
> > > us
> > >
> > >
> > > >
> > > > >
> > > > > >
> > > > > >
> > > > > sy id
> > > > >
> > > > >
> > > > >
> > > > >
> > > > > >  0 0 0 17121968 14961748 22 205 0 0 0 0  0  0  0  0  0 7960 16218
> > > > > >
> > > > > >
> > > > >
> > > >
> > > 16155 28
> > >
> > >
> > > >
> > > > >
> > > > > >
> > > > > >
> > > > > 2 71
> > > > >
> > > > >
> > > > >
> > > > >
> > > > > >  0 0 0 17121968 14961748 0 0 0  0  0  0  0  0  0  0  0 19914 41572
> > > > > >
> > > > > >
> > > > >
> > > >
> > > 41568
> > >
> > >
> > > >
> > > > >
> > > > > >
> > > > > >
> > > > > 81 3 16
> > > > >
> > > > >
> > > > >
> > > > >
> > > > > >  1 0 0 17121968 14961748 0 0 0  0  0  0  0  0  0  0  0 18711 39086
> > > > > >
> > > > > >
> > > > >
> > > >
> > > 38937
> > >
> > >
> > > >
> > > > >
> > > > > >
> > > > > >
> > > > > 80 3 17
> > > > >
> > > > >
> > > > >
> > > > >
> > > > > >  0 0 0 17121968 14961748 0 0 0  0  0  0  0  0  0  0  0 19006 39373
> > > > > >
> > > > > >
> > > > >
> > > >
> > > 39382
> > >
> > >
> > > >
> > > > >
> > > > > >
> > > > > >
> > > > > 80 3 17
> > > > >
> > > > >
> > > > >
> > > > >
> > > > > >  0 0 0 17121968 14961748 0 0 0  0  0  0  0  0  0  0  0 18719 39151
> > > > > >
> > > > > >
> > > > >
> > > >
> > > 39007
> > >
> > >
> > > >
> > > > >
> > > > > >
> > > > > >
> > > > > 80 3 16
> > > > >
> > > > >
> > > > >
> > > > >
> > > > > >  0 0 0 17121968 14961748 0 0 0  0  0  0  0  0  0  0  0 19560 41243
> > > > > >
> > > > > >
> > > > >
> > > >
> > > 40963
> > >
> > >
> > > >
> > > > >
> > > > > >
> > > > > >
> > > > > 81 4 16
> > > > >
> > > > >
> > > > >
> > > > >
> > > > > >  0 0 0 17121968 14961748 0 0 0  0  0  0  0  0  0  0  0 20498 43671
> > > > > >
> > > > > >
> > > > >
> > > >
> > > 43203
> > >
> > >
> > > >
> > > > >
> > > > > >
> > > > > >
> > > > > 81 4 16
> > > > >
> > > > >
> > > > >
> > > > >
> > > > > >  0 0 0 17121968 14961748 0 0 0  0  0  0  0  0  0  0  0 20857 44636
> > > > > >
> > > > > >
> > > > >
> > > >
> > > 44014
> > >
> > >
> > > >
> > > > >
> > > > > >
> > > > > >
> > > > > 80 4 15
> > > > >
> > > > >
> > > > >
> > > > >
> > > > > >  0 0 0 17121968 14961748 0 0 0  0  0  0  0  0  0  0  0 19149 41239
> > > > > >
> > > > > >
> > > > >
> > > >
> > > 40583
> > >
> > >
> > > >
> > > > >
> > > > > >
> > > > > >
> > > > > 80 4 16
> > > > >
> > > > >
> > > > >
> > > > >
> > > > > >  0 0 0 17121968 14961748 0 0 0  0  0  0  0  0  0  0  0 21019 44189
> > > > > >
> > > > > >
> > > > >
> > > >
> > > 43995
> > >
> > >
> > > >
> > > > >
> > > > > >
> > > > > >
> > > > > 81 4 15
> > > > >
> > > > >
> > > > >
> > > > >
> > > > > >  0 0 0 17122372 14962176 7 29 0 0  0  0  0  0  0  0  0 13062 27003
> > > > > >
> > > > > >
> > > > >
> > > >
> > > 26973
> > >
> > >
> > > >
> > > > >
> > > > > >
> > > > > >
> > > > > 46 2 52
> > > > >
> > > > >
> > > > >
> > > > >
> > > > > >  0 0 0 17122372 14962176 0 0 0  0  0  0  0  0  0  0  0  461  160
> 274
> > > > > >
> > > > > >
> > > > >
> > > >
> > > 0
> > >
> > >
> > > >
> > > > >
> > > > > >
> > > > > >
> > > > > 0 100
> > > > >
> > > > >
> > > > >
> > > > >
> > > > > > As you can see above that I am executing the program with 4
> concurrent
> > > > > > threads for 10 seconds. The output shows that each thread has
> acquired
> > > > > > the mutex lock about 400,000 times a second. The vmstat shows that
> the
> > > > > > program used about 80% of usertime, 4%system and ~15% idle. So far
> so
> > > > > > good.
> > > > > >
> > > > > > Now, let's look into program with truss case.
> > > > > >
> > > > > > $ truss -fc mutex_ops -w4 -r10
> > > > > >  number of threads:4,   run-time (in seconds)=10
> > > > > >  Thread    0:   total ops: 13419838,   ops/second:  1341983
> > > > > >  Thread    2:   total ops: 13959115,   ops/second:  1395911
> > > > > >  Thread    1:   total ops: 13414291,   ops/second:  1341429
> > > > > >  Thread    3:   total ops: 13535670,   ops/second:  1353567
> > > > > >
> > > > > > syscall               seconds   calls  errors
> > > > > > _exit                    .000       1
> > > > > > write                    .000       5
> > > > > > open                     .000       3       1
> > > > > > close                    .000       2
> > > > > > stat                     .000      10       7
> > > > > > getpid                   .000       1
> > > > > > fstat                    .000       1
> > > > > > ioctl                    .000       1
> > > > > > execve                   .000       1
> > > > > > lwp_park                 .905  106423
> > > > > > lwp_unpark               .757  106423
> > > > > > sigaction                .000       1
> > > > > > getcontext               .000       1
> > > > > > setustack                .000       5
> > > > > > mmap                     .000      16
> > > > > > munmap                   .000       2
> > > > > > getrlimit                .000       1
> > > > > > memcntl                  .000       1
> > > > > > sysconfig                .000       2
> > > > > > yield                    .182   26004
> > > > > > lwp_create               .000       4
> > > > > > lwp_exit                 .000       4
> > > > > > lwp_continue             .000       4
> > > > > > lwp_sigmask              .000       4
> > > > > > lwp_private              .000       1
> > > > > > lwp_wait                 .000       4
> > > > > > lwp_mutex_wakeup         .000       9
> > > > > > nanosleep                .000       1
> > > > > > schedctl                 .000       5
> > > > > > resolvepath              .000       4
> > > > > > lwp_mutex_timedlock      .000      32
> > > > > > getcwd                   .000       1
> > > > > >                   --------  ------   ----
> > > > > > sys totals:             1.846  238977      8
> > > > > > usr time:              21.363
> > > > > > elapsed:               10.060
> > > > > > $
> > > > > >
> > > > > > <<vmstat 1>>
> > > > > >  kthr      memory            page            disk          faults
> > > > > >
> > > > > >
> > > > >
> > > >
> > > cpu
> > >
> > >
> > > >
> > > > >
> > > > > >  r b w   swap  free  re  mf pi po fr de sr s0 s1 -- --   in   sy
> cs
> > > > > >
> > > > > >
> > > > >
> > > >
> > > us
> > >
> > >
> > > >
> > > > >
> > > > > >
> > > > > >
> > > > > sy id
> > > > >
> > > > >
> > > > >
> > > > >
> > > > > >  0 0 0 17122372 14962176 0 0 0  0  0  0  0  0  0  0  0  529  262
> 335
> > > > > >
> > > > > >
> > > > >
> > > >
> > > 0
> > >
> > >
> > > >
> > > > >
> > > > > >
> > > > > >
> > > > > 0 100
> > > > >
> > > > >
> > > > >
> > > > >
> > > > > >  0 0 0 17121240 14960660 153 632 0 0 0 0 0  0  0  0  0 25259 91754
> > > > > > 87992 37 15 48
> > > > > >  0 0 0 17121104 14960524 0 0 0  0  0  0  0  0  0  0  0 62751
> 178228
> > > > > > 179102 57 33 10
> > > > > >  0 0 0 17121104 14960524 0 0 0  0  0  0  0  0  0  0  0 56922
> 169565
> > > > > > 168507 59 30 11
> > > > > >  0 0 0 17121104 14960524 0 0 0  0  0  0  0  0  0  0  0 60935
> 178967
> > > > > > 178535 58 32 10
> > > > > >  0 0 0 17121104 14960524 0 0 0  0  0  0  0  0  0  0  0 61581
> 180239
> > > > > > 179751 58 32 10
> > > > > >  0 0 0 17121104 14960524 0 0 0  0  0  0  0  0  0  0  0 61486
> 181664
> > > > > > 180513 58 33 10
> > > > > >  1 0 0 17121104 14960524 0 0 0  0  0  0  0  0  0  0  0 67941
> 186205
> > > > > > 190703 55 35 10
> > > > > >  0 0 0 17121104 14960524 0 0 0  0  0  0  0  0  0  0  0 59981
> 175708
> > > > > > 175758 58 32 10
> > > > > >  1 0 0 17121104 14960524 0 0 0  0  0  0  0  0  0  0  0 60485
> 174557
> > > > > > 175091 58 32 11
> > > > > >  1 0 0 17121104 14960524 0 0 0  0  0  0  0  0  0  0  0 62799
> 178328
> > > > > > 179880 57 32 10
> > > > > >  0 0 0 17122236 14962040 8 17 0 0  0  0  0  0  0  0  0 19483 58122
> > > > > > 58317 19 10 71
> > > > > >  0 0 0 17122236 14962040 0 0 0  0  0  0  0  0  0  0  0  449  160
> 279
> > > > > >
> > > > > >
> > > > >
> > > >
> > > 0
> > >
> > >
> > > >
> > > > >
> > > > > >
> > > > > >
> > > > > 0 100
> > > > >
> > > > >
> > > > >
> > > > >
> > > > > > Can you spot the issue? I used the same parameters(4 concurrent
> > > > > > threads, 10 seconds run-time), but this time *with truss enabled*.
> The
> > > > > > output shows that each thread has acquired the mutex lock about
> > > > > > 1,300,000 times a second. vmstat shows that the program is using a
> lot
> > > > > > more system time than before. However, I don't know how truss can
> > > > > > cause the system time to go up, which ultimately increases the
> > > > > > performance. Am I missing something?
> > > > > >
> > > > > > BTW, I confirmed the mutex locks generated by the program using
> > > > > > dtrace. The values are indeed correct for both the cases.
> > > > > >
> > > > > > Any inputs/comments are appreciated.
> > > > > >
> > > > > > thanks.
> > > > > >
> > > > > > senthil
> > > > > > _______________________________________________
> > > > > > perf-discuss mailing list
> > > > > > perf-discuss@opensolaris.org
> > > > > >
> > > > > >
> > > > > >
> > > > > >
> > > > > >
> > > > > >
> > > > >
> > > > >
> > > >
> > >
> > >
> >
>
>
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