Re: Wow... (<-- blown away at performance)

From: Alexander Best <arundel_at_freebsd.org>
Date: Tue, 22 Feb 2011 22:33:14 +0000
On Tue Feb 22 11, Alexander Best wrote:
> On Tue Feb 22 11, Brandon Gooch wrote:
> > On Tue, Feb 22, 2011 at 2:31 PM, Alexander Best <arundel_at_freebsd.org> wrote:
> > > On Tue Feb 22 11, Garrett Cooper wrote:
> > >> On Tue, Feb 22, 2011 at 2:10 AM, Eir Nym <eirnym_at_gmail.com> wrote:
> > >> > On 22 February 2011 11:15, Garrett Cooper <yanegomi_at_gmail.com> wrote:
> > >> >>    I don't know what to say, but r218938 screams with flash videos
> > >> >> (native Linux speed). Not sure if it's the new binutils or if it's the
> > >> >> new linuxulator patches, but I can run multiple instances of youtube
> > >> >> in parallel (5 total with other miscellaneous flash animation) without
> > >> >> it totally lagging out Firefox/X11, and it appears to close the
> > >> >> instances of firefox properly now. Hopefully this version fares better
> > >> >> than r218113 did (I think I hit a kernel bug after 2 weeks uptime,
> > >> >> where my system just hardlocked for no apparent reason).
> > >> >>    Anyhow, hope others have similar results.
> > >> >> Cheers!
> > >> >> -Garrett
> > >> >>
> > >> >> $ uname -a
> > >> >> FreeBSD bayonetta.local 9.0-CURRENT FreeBSD 9.0-CURRENT #0 r218938M:
> > >> >> Mon Feb 21 23:10:51 PST 2011
> > >> >> gcooper_at_bayonetta.local:/usr/obj/usr/src/sys/BAYONETTA  amd64
> > >> >
> > >> > Which FlashPlayer version do you test? Adobe has made significant
> > >> > performance changes in 10.2 (from 10.1). You can search for StageVideo
> > >> > performance to learn more about. Youtube already use them since 10.2
> > >> > beta
> > >>
> > >>     linux-f10-flashplugin-10.1r102.65 . The performance increases are
> > >> claimed to be "up to 85%" on the Stage Video site, but I'm seeing a
> > >> more than 200% increase (now it actually scales between multiple
> > >> instances, instead of croaks with one instance, tiling up and down the
> > >> screen when moving the window slider for instance or switching tabs).
> > >> Besides, it seems like it needs external support from the video
> > >> driver, and I'm not sure that that bridge exists in the linuxulator.
> > >>     Also, it looks like npviewer.bin still hangs to resources on until
> > >> Firefox closes (or I kill it :)..), so something still needs to be
> > >> resolved there, but that isn't a regression (it's acted that way for
> > >> ages), and shouldn't be too hard to do.
> > >
> > > i think the problem with npviewer.bin having to be killed by hand is a futex
> > > issue in combination with a high number of threads. this is the output of a
> > > test from darren hart's futex test suite under freebsd 9.0:
> > >
> > > futex_wait: Measure FUTEX_WAIT operations per second
> > >        Arguments: iterations=100000000 threads=1
> > > Result: 18622 Kiter/s
> > > futex_wait: Measure FUTEX_WAIT operations per second
> > >        Arguments: iterations=100000000 threads=2
> > > Result: 15469 Kiter/s
> > > futex_wait: Measure FUTEX_WAIT operations per second
> > >        Arguments: iterations=100000000 threads=3
> > > Result: 12713 Kiter/s
> > > futex_wait: Measure FUTEX_WAIT operations per second
> > >        Arguments: iterations=100000000 threads=4
> > > Result: 12247 Kiter/s
> > > futex_wait: Measure FUTEX_WAIT operations per second
> > >        Arguments: iterations=100000000 threads=5
> > > Result: 11814 Kiter/s
> > > futex_wait: Measure FUTEX_WAIT operations per second
> > >        Arguments: iterations=100000000 threads=6
> > > Result: 13468 Kiter/s
> > > futex_wait: Measure FUTEX_WAIT operations per second
> > >        Arguments: iterations=100000000 threads=8
> > > Result: 12061 Kiter/s
> > > futex_wait: Measure FUTEX_WAIT operations per second
> > >        Arguments: iterations=100000000 threads=10
> > > Result: 12854 Kiter/s
> > > futex_wait: Measure FUTEX_WAIT operations per second
> > >        Arguments: iterations=100000000 threads=12
> > > Result: 12999 Kiter/s
> > > futex_wait: Measure FUTEX_WAIT operations per second
> > >        Arguments: iterations=100000000 threads=16
> > > Result: 12402 Kiter/s
> > > futex_wait: Measure FUTEX_WAIT operations per second
> > >        Arguments: iterations=100000000 threads=24
> > > Result: 9815 Kiter/s
> > > futex_wait: Measure FUTEX_WAIT operations per second
> > >        Arguments: iterations=100000000 threads=32
> > > Result: 8518 Kiter/s
> > > futex_wait: Measure FUTEX_WAIT operations per second
> > >        Arguments: iterations=100000000 threads=64
> > >        ERROR: Resource temporarily unavailable: pthread_create
> > > Result: ERROR
> > > futex_wait: Measure FUTEX_WAIT operations per second
> > >        Arguments: iterations=100000000 threads=128
> > >        ERROR: Resource temporarily unavailable: pthread_create
> > > Result: ERROR
> > > futex_wait: Measure FUTEX_WAIT operations per second
> > >        Arguments: iterations=100000000 threads=256
> > >        ERROR: Resource temporarily unavailable: pthread_create
> > > Result: ERROR
> > > futex_wait: Measure FUTEX_WAIT operations per second
> > >        Arguments: iterations=100000000 threads=512
> > >        ERROR: Resource temporarily unavailable: pthread_create
> > > Result: ERROR
> > > futex_wait: Measure FUTEX_WAIT operations per second
> > >        Arguments: iterations=100000000 threads=1024
> > >        ERROR: Resource temporarily unavailable: pthread_create
> > > Result: ERROR
> > >
> > > cheers.
> > > alex
> > 
> > Have you found any method or workaround to mitigate this issue?

i did a ktrace -i and linux_kdump run and the results are quite interesting.
with only 1 thread linux_sys_futex() *never* failed with EAGAIN. starting
with 2 threads however i'm seeing an increasing number of linux_sys_futex()
failures (all with EAGAIN).

the overhead is quite massive. linux_kdump > /tmp/futex-failure produced 941
megs of output. doing
grep -v "futex_wait" futex-failure > futex-grep
produces an output of 192K!! so it's quite obvious that the futex_wait stuff
is responsible for causing massive activity, due to the constant failures and
retries.

here's a bit of output:

 32126 futex_wait RET   linux_sys_futex -1 errno 35 Resource temporarily unavailable
 32125 futex_wait RET   linux_sys_futex 0
 32126 futex_wait CALL  linux_sys_futex(0xffffdb5c,0x81,0x1,0,0,0)
 32126 futex_wait RET   linux_sys_futex 0
 32126 futex_wait CALL  linux_sys_futex(0xffffdb5c,0x81,0x1,0,0,0)
 32125 futex_wait CALL  linux_sys_futex(0xffffdb5c,0x80,0x2,0,0,0)
 32126 futex_wait RET   linux_sys_futex 0
 32125 futex_wait RET   linux_sys_futex -1 errno 35 Resource temporarily unavailable
 32126 futex_wait CALL  linux_sys_futex(0xffffdb5c,0x80,0x2,0,0,0)
 32125 futex_wait CALL  linux_sys_futex(0xffffdb5c,0x81,0x1,0,0,0)
 32126 futex_wait RET   linux_sys_futex -1 errno 35 Resource temporarily unavailable
 32125 futex_wait RET   linux_sys_futex 0
 32126 futex_wait CALL  linux_sys_futex(0xffffdb5c,0x81,0x1,0,0,0)
 32126 futex_wait RET   linux_sys_futex 0
 32126 futex_wait CALL  linux_sys_futex(0xffffdb5c,0x80,0x2,0,0,0)
 32125 futex_wait CALL  linux_sys_futex(0xffffdb5c,0x81,0x1,0,0,0)
 32126 futex_wait RET   linux_sys_futex -1 errno 35 Resource temporarily unavailable
 32125 futex_wait RET   linux_sys_futex 0
 32126 futex_wait CALL  linux_sys_futex(0xffffdb5c,0x81,0x1,0,0,0)
 32126 futex_wait RET   linux_sys_futex 0
 32126 futex_wait CALL  linux_sys_futex(0xffffdb5c,0x80,0x2,0,0,0)
 32125 futex_wait CALL  linux_sys_futex(0xffffdb5c,0x81,0x1,0,0,0)
 32126 futex_wait RET   linux_sys_futex -1 errno 35 Resource temporarily unavailable
 32125 futex_wait RET   linux_sys_futex 0
 32126 futex_wait CALL  linux_sys_futex(0xffffdb5c,0x81,0x1,0,0,0)
 32126 futex_wait RET   linux_sys_futex 0
 32126 futex_wait CALL  linux_sys_futex(0xffffdb5c,0x81,0x1,0,0,0)
 32125 futex_wait CALL  linux_sys_futex(0xffffdb5c,0x80,0x2,0,0,0)
 32126 futex_wait RET   linux_sys_futex 0
 32125 futex_wait RET   linux_sys_futex -1 errno 35 Resource temporarily unavailable
 32125 futex_wait CALL  linux_sys_futex(0xffffdb5c,0x81,0x1,0,0,0)
 32126 futex_wait CALL  linux_sys_futex(0xffffdb5c,0x80,0x2,0,0,0)
 32125 futex_wait RET   linux_sys_futex 0
 32126 futex_wait RET   linux_sys_futex -1 errno 35 Resource temporarily unavailable
 32126 futex_wait CALL  linux_sys_futex(0xffffdb5c,0x80,0x2,0,0,0)
 32125 futex_wait CALL  linux_sys_futex(0xffffdb5c,0x81,0x1,0,0,0)
 32126 futex_wait RET   linux_sys_futex -1 errno 35 Resource temporarily unavailable
 32125 futex_wait RET   linux_sys_futex 0
 32126 futex_wait CALL  linux_sys_futex(0xffffdb5c,0x81,0x1,0,0,0)
 32126 futex_wait RET   linux_sys_futex 0
 32126 futex_wait CALL  linux_sys_futex(0xffffdb5c,0x80,0x2,0,0,0)
 32125 futex_wait CALL  linux_sys_futex(0xffffdb5c,0x81,0x1,0,0,0)
 32126 futex_wait RET   linux_sys_futex -1 errno 35 Resource temporarily unavailable
 32125 futex_wait RET   linux_sys_futex 0
 32126 futex_wait CALL  linux_sys_futex(0xffffdb5c,0x81,0x1,0,0,0)
 32126 futex_wait RET   linux_sys_futex 0
 32126 futex_wait CALL  linux_sys_futex(0xffffdb5c,0x80,0x2,0,0,0)
 32125 futex_wait CALL  linux_sys_futex(0xffffdb5c,0x81,0x1,0,0,0)
 32126 futex_wait RET   linux_sys_futex -1 errno 35 Resource temporarily unavailable
 32125 futex_wait RET   linux_sys_futex 0
 32126 futex_wait CALL  linux_sys_futex(0xffffdb5c,0x81,0x1,0,0,0)
 32126 futex_wait RET   linux_sys_futex 0
 32126 futex_wait CALL  linux_sys_futex(0xffffdb5c,0x80,0x2,0,0,0)
 32125 futex_wait CALL  linux_sys_futex(0xffffdb5c,0x81,0x1,0,0,0)
 32126 futex_wait RET   linux_sys_futex -1 errno 35 Resource temporarily unavailable

cheers.
alex

> 
> no. i've increased the kern.threads.max_threads_per_proc value, but that had
> no effect. so it seems to be a bug in the linuxulator's futex implementation.
> 
> cheers.
> alex
> 
> > 
> > -Brandon
> 
> -- 
> a13x

-- 
a13x
Received on Tue Feb 22 2011 - 21:33:14 UTC

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