From: Simon Kirby <sim@hostway.ca>
To: linux-kernel@vger.kernel.org,
Shawn Bohrer <shawn.bohrer@gmail.com>,
Eric Dumazet <eric.dumazet@gmail.com>
Subject: sys_epoll_wait high CPU load in 2.6.37
Date: Tue, 25 Jan 2011 16:09:32 -0800 [thread overview]
Message-ID: <20110126000932.GA23089@hostway.ca> (raw)
Hello!
Since upgrading 2.6.36 -> 2.6.37, dovecot's "anvil" process seems to end
up taking a lot more time in "top", and "perf top" shows output like this
(system-wide):
samples pcnt function DSO
_______ _____ _____________________________ __________________________
2405.00 68.8% sys_epoll_wait [kernel.kallsyms]
33.00 0.9% mail_cache_lookup_iter_next libdovecot-storage.so.0.0.0
30.00 0.9% _raw_spin_lock [kernel.kallsyms]
...etc...
It only wakes up 5-10 times per second or so (on this box), and does
stuff like this:
epoll_wait(12, {{EPOLLIN, {u32=19417616, u64=19417616}}}, 25, 2147483647) = 1
read(29, "PENALTY-GET\t192.168.31.10\n"..., 738) = 26
write(29, "0 0\n"..., 4) = 4
epoll_wait(12, {{EPOLLIN, {u32=19395632, u64=19395632}}}, 25, 2147483647) = 1
read(18, "LOOKUP\tpop3/192.168.31.10/tshield"..., 668) = 58
write(18, "0\n"..., 2) = 2
epoll_wait(12, {{EPOLLIN, {u32=19373072, u64=19373072}}}, 25, 2147483647) = 1
read(7, "CONNECT\t3490\tpop3/192.168.31.10/t"..., 254) = 64
epoll_wait(12, {{EPOLLIN, {u32=19373072, u64=19373072}}}, 25, 2147483647) = 1
read(7, "DISCONNECT\t3482\tpop3/192.168.31.1"..., 190) = 62
Anything obvious here? anvil talks over UNIX sockets to the rest of
dovecot, and uses epoll_wait. So, suspect commits might be:
95aac7b1cd224f568fb83937044cd303ff11b029
5456f09aaf88731e16dbcea7522cb330b6846415
or other bits from
git log v2.6.36..v2.6.37 net/unix/af_unix.c fs/eventpoll.c
I suspect it has something to do with that "infinite value" check removal
in that first commit. It doesn't show up easily on a test box, but I can
try reverting 95aac7b1cd in production if it's not obvious.
Simon-
next reply other threads:[~2011-01-26 0:09 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-01-26 0:09 Simon Kirby [this message]
2011-01-26 7:18 ` sys_epoll_wait high CPU load in 2.6.37 Eric Dumazet
2011-01-26 11:16 ` Eric Dumazet
2011-01-26 15:31 ` Davide Libenzi
2011-01-26 15:43 ` Eric Dumazet
2011-01-26 15:52 ` Davide Libenzi
2011-01-26 15:59 ` Eric Dumazet
2011-01-26 16:13 ` Eric Dumazet
2011-01-26 17:20 ` Shawn Bohrer
2011-01-26 17:51 ` Eric Dumazet
2011-01-26 18:06 ` Davide Libenzi
2011-01-26 18:18 ` Eric Dumazet
2011-01-26 18:45 ` Eric Dumazet
2011-01-28 0:17 ` Davide Libenzi
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