svn commit: r333744 - in head/sys: kern sys
Matthew Macy
mmacy at freebsd.org
Thu Jun 7 02:12:05 UTC 2018
On Wed, Jun 6, 2018 at 12:03 PM, Peter Holm <peter at holm.cc> wrote:
> On Thu, May 17, 2018 at 05:59:35PM +0000, Matt Macy wrote:
>> Author: mmacy
>> Date: Thu May 17 17:59:35 2018
>> New Revision: 333744
>> URL: https://svnweb.freebsd.org/changeset/base/333744
>>
>> Log:
>> AF_UNIX: make unix socket locking finer grained
>>
>> This change moves to using a reference count across lock drop / reacquire
>> to guarantee liveness.
>>
>> Currently sends on unix sockets contend heavily on read locking the list lock.
>> unix1_processes in will-it-scale peaks at 6 processes and then declines.
>>
>> With this change I get a substantial improvement in number of operations per second
>> with 96 processes:
>>
>> x before
>> + after
>> N Min Max Median Avg Stddev
>> x 11 1688420 1696389 1693578 1692766.3 2971.1702
>> + 10 63417955 71030114 70662504 69576423 2374684.6
>> Difference at 95.0% confidence
>> 6.78837e+07 +/- 1.49463e+06
>> 4010.22% +/- 88.4246%
>> (Student's t, pooled s = 1.63437e+06)
>>
>> And even for 2 processes shows a ~18% improvement.
>> "Small" iron changes (1, 2, and 4 processes):
>>
>> x before1
>> + after1.2
>> +------------------------------------------------------------------------+
>> | + |
>> | x + |
>> | x + |
>> | x + |
>> | x ++ |
>> | xx ++ |
>> |x x xx ++ |
>> | |__________________A_____M_____AM____||
>> +------------------------------------------------------------------------+
>> N Min Max Median Avg Stddev
>> x 10 1131648 1197750 1197138.5 1190369.3 20651.839
>> + 10 1203840 1205056 1204919 1204827.9 353.27404
>> Difference at 95.0% confidence
>> 14458.6 +/- 13723
>> 1.21463% +/- 1.16683%
>> (Student's t, pooled s = 14605.2)
>>
>> x before2
>> + after2.2
>> +------------------------------------------------------------------------+
>> | +|
>> | +|
>> | +|
>> | +|
>> | +|
>> | +|
>> | x +|
>> | x +|
>> | x xx +|
>> |x xxxx +|
>> | |___AM_| A|
>> +------------------------------------------------------------------------+
>> N Min Max Median Avg Stddev
>> x 10 1972843 2045866 2038186.5 2030443.8 21367.694
>> + 10 2400853 2402196 2401043.5 2401172.7 385.40024
>> Difference at 95.0% confidence
>> 370729 +/- 14198.9
>> 18.2585% +/- 0.826943%
>> (Student's t, pooled s = 15111.7)
>>
>> x before4
>> + after4.2
>> N Min Max Median Avg Stddev
>> x 10 3986994 3991728 3990137.5 3989985.2 1300.0164
>> + 10 4799990 4806664 4806116.5 4805194 1990.6625
>> Difference at 95.0% confidence
>> 815209 +/- 1579.64
>> 20.4314% +/- 0.0421713%
>> (Student's t, pooled s = 1681.19)
>>
>> Tested by: pho
>> Reported by: mjg
>> Approved by: sbruno
>> Sponsored by: Limelight Networks
>> Differential Revision: https://reviews.freebsd.org/D15430
>>
>> Modified:
>> head/sys/kern/uipc_usrreq.c
>> head/sys/sys/unpcb.h
>>
>> Modified: head/sys/kern/uipc_usrreq.c
>> ==============================================================================
>> --- head/sys/kern/uipc_usrreq.c Thu May 17 17:57:41 2018 (r333743)
>
> This commit seems to cause this:
>
> 20180606 20:44:37 all (1/1): datagram.sh
> panic: _mtx_lock_sleep: recursed on non-recursive mutex unp_mtx @ ../../../kern/uipc_usrreq.c:354
>
> cpuid = 91
> time = 1528310678
> KDB: stack backtrace:
> db_trace_self_wrapper() at db_trace_self_wrapper+0x2b/frame 0xfffffe00f3a2bcd0
> vpanic() at vpanic+0x1a3/frame 0xfffffe00f3a2bd30
> doadump() at doadump/frame 0xfffffe00f3a2bdb0
> __mtx_lock_sleep() at __mtx_lock_sleep+0x49d/frame 0xfffffe00f3a2be30
> __mtx_lock_flags() at __mtx_lock_flags+0xf9/frame 0xfffffe00f3a2be80
> unp_connectat() at unp_connectat+0x2ec/frame 0xfffffe00f3a2c110
> soconnectat() at soconnectat+0xe8/frame 0xfffffe00f3a2c160
> kern_connectat() at kern_connectat+0x10f/frame 0xfffffe00f3a2c1c0
> sys_connect() at sys_connect+0x77/frame 0xfffffe00f3a2c200
> amd64_syscall() at amd64_syscall+0x2a7/frame 0xfffffe00f3a2c330
> fast_syscall_common() at fast_syscall_common+0x101/frame 0xfffffe00f3a2c330
> --- syscall (98, FreeBSD ELF64, sys_connect), rip = 0x80040081a, rsp = 0x7fffffffe2e8, rbp = 0x7fffffffe770 ---
> KDB: enter: panic
> [ thread pid 1276 tid 100966 ]
> Stopped at kdb_enter+0x3b: movq $0,kdb_why
> db> x/s version
> version: FreeBSD 12.0-CURRENT #0 r333744: Wed Jun 6 20:35:18 CEST 2018\012 pho at flix1a.netperf.freebsd.org:/usr/src/sys/amd64/compile/PHO\012
> db>
I fixed this in 334175 and 334185.
>
> The stack trace is different on HEAD:
>
> panic: mutex unp not owned at ../../../kern/uipc_usrreq.c:879
> cpuid = 47
> time = 1528311629
> KDB: stack backtrace:
> db_trace_self_wrapper() at db_trace_self_wrapper+0x2b/frame 0xfffffe00ee593ca0
> vpanic() at vpanic+0x1a3/frame 0xfffffe00ee593d00
> panic() at panic+0x43/frame 0xfffffe00ee593d60
> __mtx_assert() at __mtx_assert+0xb4/frame 0xfffffe00ee593d70
> uipc_disconnect() at uipc_disconnect+0x93/frame 0xfffffe00ee593dc0
> soclose() at soclose+0xa5/frame 0xfffffe00ee593e30
> closef() at closef+0x1f5/frame 0xfffffe00ee593ec0
> fdescfree_fds() at fdescfree_fds+0x90/frame 0xfffffe00ee593f10
> fdescfree() at fdescfree+0x480/frame 0xfffffe00ee593fd0
> exit1() at exit1+0x500/frame 0xfffffe00ee594040
> sigexit() at sigexit+0xae8/frame 0xfffffe00ee594220
> postsig() at postsig+0x1cf/frame 0xfffffe00ee5942f0
> ast() at ast+0x4b8/frame 0xfffffe00ee594330
> doreti_ast() at doreti_ast+0x1f/frame 0x7fffffffe760
> KDB: enter: panic
> [ thread pid 1013 tid 100834 ]
> Stopped at kdb_enter+0x3b: movq $0,kdb_why
> db> x/s version
> version: FreeBSD 12.0-CURRENT #0 r334723: Wed Jun 6 20:53:32 CEST 2018\012 pho at flix1a.netperf.freebsd.org:/usr/src/sys/amd64/compile/PHO\012
> db>
I'll take a look.
-M
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