Yes, I did, but have no effect.
I want to ask is, why David's patch not used. Thanks. Cong Wang said, at 2/27/2016 2:29 PM: > On Fri, Feb 26, 2016 at 8:40 PM, zhao ya <marywangran0...@gmail.com> wrote: >> From: Zhao Ya <marywangran0...@gmail.com> >> Date: Sat, 27 Feb 2016 10:06:44 +0800 >> Subject: [PATCH] IPIP tunnel performance improvement >> >> bypass the logic of each packet's own neighbour creation when using >> pointopint or loopback device. >> >> Recently, in our tests, met a performance problem. >> In a large number of packets with different target IP address through >> ipip tunnel, PPS will decrease sharply. >> >> The output of perf top are as follows, __write_lock_failed is of the first: >> - 5.89% [kernel] [k] __write_lock_failed >> -__write_lock_failed a >> -_raw_write_lock_bh a >> -__neigh_create a >> -ip_finish_output a >> -ip_output a >> -ip_local_out a >> >> The neighbour subsystem will create a neighbour object for each target >> when using pointopint device. When massive amounts of packets with diff- >> erent target IP address to be xmit through a pointopint device, these >> packets will suffer the bottleneck at write_lock_bh(&tbl->lock) after >> creating the neighbour object and then inserting it into a hash-table >> at the same time. >> >> This patch correct it. Only one or little amounts of neighbour objects >> will be created when massive amounts of packets with different target IP >> address through ipip tunnel. >> >> As the result, performance will be improved. > > Well, you just basically revert another bug fix: > > commit 0bb4087cbec0ef74fd416789d6aad67957063057 > Author: David S. Miller <da...@davemloft.net> > Date: Fri Jul 20 16:00:53 2012 -0700 > > ipv4: Fix neigh lookup keying over loopback/point-to-point devices. > > We were using a special key "0" for all loopback and point-to-point > device neigh lookups under ipv4, but we wouldn't use that special > key for the neigh creation. > > So basically we'd make a new neigh at each and every lookup :-) > > This special case to use only one neigh for these device types > is of dubious value, so just remove it entirely. > > Reported-by: Eric Dumazet <eric.duma...@gmail.com> > Signed-off-by: David S. Miller <da...@davemloft.net> > > which would bring the neigh entries counting problem back... > > Did you try to tune the neigh gc parameters for your case? > > Thanks. >
