svn commit: r333744 - in head/sys: kern sys
Peter Holm
peter at holm.cc
Wed Jun 6 19:03:57 UTC 2018
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>
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>
- Peter
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