Date: Sun, 15 Apr 2012 18:16:13 +0000 From: Alexander Best <arundel@freebsd.org> To: Alexander Leidinger <Alexander@Leidinger.net> Cc: freebsd-emulation@freebsd.org Subject: Re: [PATCH] pipe2 for Linuxulator Message-ID: <20120415181613.GA52958@freebsd.org> In-Reply-To: <20120415144155.GA15993@freebsd.org> References: <20120415000246.0000736b@unknown> <20120415000216.GA53624@freebsd.org> <20120415101157.GA67049@freebsd.org> <20120415112308.GA77985@freebsd.org> <20120415134444.000005cc@unknown> <20120415115112.GA83717@freebsd.org> <20120415143441.00000948@unknown> <20120415130306.GA95208@freebsd.org> <20120415163059.0000715d@unknown> <20120415144155.GA15993@freebsd.org>
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On Sun Apr 15 12, Alexander Best wrote:
> On Sun Apr 15 12, Alexander Leidinger wrote:
> > On Sun, 15 Apr 2012 13:03:06 +0000 Alexander Best <arundel@freebsd.org>
> > wrote:
> >
> > > On Sun Apr 15 12, Alexander Leidinger wrote:
> > > > On Sun, 15 Apr 2012 11:51:12 +0000 Alexander Best
> > > > <arundel@freebsd.org> wrote:
> > > >
> > > > > ahh ok. i've managed to get some stats via stats_timing.d. this
> > > > > is a snapshot during which a newly loaded tab in chromium was
> > > > > unresponsive for about 5 seconds. without the linux flash plugin
> > > > > running i never experienced such lock ups.
> > > > >
> > > > > i've attached the d-script stats.
> > > >
> > > > What about the trace_futexes script and the two check_* scripts? The
> > > > stats show that there is a lot of work spend in the futexes.
> > >
> > > i'm having problems with those scripts. they have a negative impact
> > > on the linux processes. when i have the player at www.mixcloud.com
> > > running and run those scripts the music stops and the flash graphics
> > > get all distorted. here's some output from the trace_futexes.d script:
> > >
> > > otaku% sudo ./trace_futexes.d
> > > dtrace: 808 dynamic variable drops with non-empty dirty list
> > > dtrace: 833 failed speculations (available buffer(s) still busy)
> >
> > You should increase the buffers in the scripts, they are overflowing.
> >
> > [...]
> > > ERROR: missing_access_check in linuxulator32:futex:futex_atomic_op
> >
> > This is missing code in the kernel... or a superfluous comment.
> >
> > > kernel`ia32_syscall+0x299
> > > kernel`0xffffffff805b05e5
> > >
> > > dtrace: ERROR: open failed: No such file or directory
> > > `0x287b6533
> > > Fatal error 'mutex is on list' at line 424 in
> > > file /usr/github-freebsd-head/lib/libthr/thread/thr_mutex.c (errno =
> > > 0)
> >
> > No idea.
> >
> > > this is from the check_error.d script:
> > >
> > > otaku% sudo ./check_error.d
> > > ERROR: sleep_error in linuxulator32:futex:futex_sleep
> >
> > Well... the sx_sleep returned with a non-null value. I assume this
> > means a timeout fired. No idea if it is good or bad.
> >
> > > kernel`ia32_syscall+0x299
> > > kernel`0xffffffff805b05e5
> > >
> > > 0x287b6278
> > > 0x2a12800029d5fa5c
> > > ERROR: sleep_error in linuxulator32:futex:futex_wait
> >
> > As above.
> >
> > > kernel`ia32_syscall+0x299
> > > kernel`0xffffffff805b05e5
> > >
> > > 0x287b6278
> > > 0x2a12800029d5fa5c
> >
> > > the check_internal_locks.d scripts seems to work fine. i think we
> > > talked about the failed-speculation-warnings beforehand and that they
> > > aren't critical:
> >
> > Yes and no... you do not have enough buffers to store all the info the
> > script want to store. As such it does not work as intended.
>
> i've set
>
> #pragma D option dynvarsize=512m
> #pragma D option specsize=512m
>
> in check_internal_locks.d
>
> however i get a warning that the size got downgraded and still the buffers
> don't seem to be large enough:
>
> dtrace: dynamic variable size lowered to 256m
> dtrace: 220 failed speculations (available buffer(s) still busy)
> dtrace: 206 failed speculations (available buffer(s) still busy)
> dtrace: 205 failed speculations (available buffer(s) still busy)
> dtrace: 206 failed speculations (available buffer(s) still busy)
> dtrace: 182 failed speculations (available buffer(s) still busy)
> dtrace: 219 failed speculations (available buffer(s) still busy)
> dtrace: 194 failed speculations (available buffer(s) still busy)
> dtrace: 210 failed speculations (available buffer(s) still busy)
> dtrace: 218 failed speculations (available buffer(s) still busy)
> dtrace: 206 failed speculations (available buffer(s) still busy)
> dtrace: 222 failed speculations (available buffer(s) still busy)
> dtrace: 214 failed speculations (available buffer(s) still busy)
> dtrace: 213 failed speculations (available buffer(s) still busy)
> dtrace: 205 failed speculations (available buffer(s) still busy)
> dtrace: 216 failed speculations (available buffer(s) still busy)
> dtrace: 220 failed speculations (available buffer(s) still busy)
> dtrace: 210 failed speculations (available buffer(s) still busy)
>
> maybe the problem with the above errors was that my kernel got built with
> dtrace support, but my world didn't. i'm now rebuilding and installing world.
> maybe that fixes some of the issues.
>
> >
> >
> > > Number of locks per type:
> > > emul_shared_rlock 3
> > > emul_shared_wlock 37
> > > emul_lock 55
> > > futex_mtx 31179
here are the results for a single flash instance:
otaku% sudo time ./check_internal_locks.d
dtrace: 217 failed speculations (available buffer(s) still busy)
dtrace: 223 failed speculations (available buffer(s) still busy)
dtrace: 218 failed speculations (available buffer(s) still busy)
dtrace: 216 failed speculations (available buffer(s) still busy)
dtrace: 206 failed speculations (available buffer(s) still busy)
dtrace: 200 failed speculations (available buffer(s) still busy)
dtrace: 218 failed speculations (available buffer(s) still busy)
dtrace: 246 failed speculations (available buffer(s) still busy)
dtrace: 218 failed speculations (available buffer(s) still busy)
dtrace: 258 failed speculations (available buffer(s) still busy)
dtrace: 223 failed speculations (available buffer(s) still busy)
dtrace: 246 failed speculations (available buffer(s) still busy)
dtrace: 240 failed speculations (available buffer(s) still busy)
dtrace: 258 failed speculations (available buffer(s) still busy)
dtrace: 252 failed speculations (available buffer(s) still busy)
dtrace: 230 failed speculations (available buffer(s) still busy)
dtrace: 257 failed speculations (available buffer(s) still busy)
^C
dtrace: 227 failed speculations (available buffer(s) still busy)
Number of locks per type:
futex_mtx 4585
18,48 real 0,10 user 0,36 sys
and here for two flash tabs:
otaku% sudo time ./check_internal_locks.d
dtrace: 1148 failed speculations (available buffer(s) still busy)
dtrace: 1524 failed speculations (available buffer(s) still busy)
dtrace: 1604 failed speculations (available buffer(s) still busy)
dtrace: 1029 failed speculations (available buffer(s) still busy)
dtrace: 1471 failed speculations (available buffer(s) still busy)
dtrace: 1466 failed speculations (available buffer(s) still busy)
dtrace: 1720 failed speculations (available buffer(s) still busy)
dtrace: 1049 failed speculations (available buffer(s) still busy)
dtrace: 1549 failed speculations (available buffer(s) still busy)
dtrace: 1421 failed speculations (available buffer(s) still busy)
dtrace: 1595 failed speculations (available buffer(s) still busy)
dtrace: 1097 failed speculations (available buffer(s) still busy)
dtrace: 1853 failed speculations (available buffer(s) still busy)
dtrace: 1900 failed speculations (available buffer(s) still busy)
dtrace: 1729 failed speculations (available buffer(s) still busy)
dtrace: 1389 failed speculations (available buffer(s) still busy)
dtrace: 1314 failed speculations (available buffer(s) still busy)
dtrace: 1712 failed speculations (available buffer(s) still busy)
^C
dtrace: 1615 failed speculations (available buffer(s) still busy)
Number of locks per type:
futex_mtx 29364
19,41 real 0,09 user 0,32 sys
...and for three flash tabs:
otaku% sudo time ./check_internal_locks.d
dtrace: 535 failed speculations (available buffer(s) still busy)
dtrace: 213 failed speculations (available buffer(s) still busy)
dtrace: 282 failed speculations (available buffer(s) still busy)
dtrace: 571 failed speculations (available buffer(s) still busy)
dtrace: 666 failed speculations (available buffer(s) still busy)
dtrace: 857 failed speculations (available buffer(s) still busy)
dtrace: 1310 failed speculations (available buffer(s) still busy)
dtrace: 1277 failed speculations (available buffer(s) still busy)
dtrace: 118 failed speculations (available buffer(s) still busy)
dtrace: 1503 failed speculations (available buffer(s) still busy)
dtrace: 2069 failed speculations (available buffer(s) still busy)
dtrace: 3562 failed speculations (available buffer(s) still busy)
dtrace: 6561 failed speculations (available buffer(s) still busy)
dtrace: 3750 failed speculations (available buffer(s) still busy)
dtrace: 2569 failed speculations (available buffer(s) still busy)
dtrace: 1362 failed speculations (available buffer(s) still busy)
dtrace: 2722 failed speculations (available buffer(s) still busy)
dtrace: 3461 failed speculations (available buffer(s) still busy)
dtrace: 2579 failed speculations (available buffer(s) still busy)
dtrace: 3451 failed speculations (available buffer(s) still busy)
dtrace: 2325 failed speculations (available buffer(s) still busy)
^C
dtrace: 2632 failed speculations (available buffer(s) still busy)
Number of locks per type:
emul_shared_wlock 14
emul_lock 20
futex_mtx 45571
22,46 real 0,11 user 0,35 sys
i've tuned the script to have the maximum buffer size of 256 megabyte via
#pragma D option dynvarsize=256m
#pragma D option specsize=256m
...still the buffers seem to be too small.
also...even after installing a fresh kernel and world with dtrace enabled,
the "check_error.d" and "trace_futexes.d" fail and sometimes even render
the flash instance unusable.
cheers.
alex
> >
> > Depending on how long you traced: that's a lot of futex operations.
>
> i traced for ~ 5 seconds. i'll make sure to prepend the time command to any
> dtrace script next time to give you more exact numbers.
>
> cheers.
> alex
>
> >
> > Bye,
> > Alexander.
> >
> > --
> > http://www.Leidinger.net Alexander @ Leidinger.net: PGP ID = B0063FE7
> > http://www.FreeBSD.org netchild @ FreeBSD.org : PGP ID = 72077137
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