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From: Eric Dumazet <eric.dumazet@gmail.com>
To: David Miller <davem@davemloft.net>
Cc: therbert@google.com, alexander.h.duyck@intel.com, netdev@vger.kernel.org
Subject: Re: Performance regression on kernels 3.10 and newer
Date: Sat, 06 Sep 2014 07:45:04 -0700	[thread overview]
Message-ID: <1410014704.11872.16.camel@edumazet-glaptop2.roam.corp.google.com> (raw)
In-Reply-To: <20140821.162406.2076033247433267586.davem@davemloft.net>

On Thu, 2014-08-21 at 16:24 -0700, David Miller wrote:
> From: Tom Herbert <therbert@google.com>
> Date: Thu, 14 Aug 2014 16:25:53 -0700
> 
> > I don't know if it's the same problem, but I did post a patch back in
> > January that would resolve false sharing of dst->__refcnt and rt_genid
> > in the same cacheline. We could revisit that if it helps.
> 
> I think that regardless of what happens in the discussion here, you
> should repost that patch.

I believe this wont be necessary, the real meat is elsewhere.

There are very few cases where we really need to keep the dst attached
to skb.

Its mostly because of IP early demux, and its possible to take care of
the fast path (where sk->sk_rx_dst is set), and simply drop dst before
prequeue in this case.

Same stuff for the backlog, used when socket is owned by user.

I'll send a patch.

  reply	other threads:[~2014-09-06 14:45 UTC|newest]

Thread overview: 57+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-08-14 18:19 Performance regression on kernels 3.10 and newer Alexander Duyck
2014-08-14 18:46 ` Eric Dumazet
2014-08-14 19:50   ` Eric Dumazet
2014-08-14 19:59   ` Rick Jones
2014-08-14 20:31     ` Alexander Duyck
2014-08-14 20:51       ` Eric Dumazet
2014-08-14 20:46     ` Eric Dumazet
2014-08-14 23:16   ` Alexander Duyck
2014-08-14 23:20     ` David Miller
2014-08-14 23:25       ` Tom Herbert
2014-08-21 23:24         ` David Miller
2014-09-06 14:45           ` Eric Dumazet [this message]
2014-09-06 15:27             ` Eric Dumazet
2014-09-06 15:46               ` Eric Dumazet
2014-09-06 16:38                 ` Eric Dumazet
2014-09-06 18:21                   ` Eric Dumazet
2014-09-07 19:05                     ` [PATCH net] ipv6: refresh rt6i_genid in ip6_pol_route() Eric Dumazet
2014-09-07 22:54                       ` David Miller
2014-09-08  4:18                         ` Eric Dumazet
2014-09-08  4:27                           ` David Miller
2014-09-08  4:43                             ` Eric Dumazet
2014-09-08  4:59                               ` David Miller
2014-09-08  5:07                                 ` Eric Dumazet
2014-09-08  8:11                                   ` Nicolas Dichtel
2014-09-08 10:28                                     ` Eric Dumazet
2014-09-08 12:16                                       ` Nicolas Dichtel
2014-09-08 18:48                                   ` Vlad Yasevich
2014-09-09 12:58                                   ` Hannes Frederic Sowa
2014-09-10  9:31                                     ` [PATCH net-next] ipv6: implement rt_genid_bump_ipv6 with fn_sernum and remove rt6i_genid Hannes Frederic Sowa
2014-09-10 13:26                                       ` Vlad Yasevich
2014-09-10 13:42                                         ` Hannes Frederic Sowa
2014-09-10 20:09                                       ` David Miller
2014-09-11  8:30                                         ` Hannes Frederic Sowa
2014-09-11 12:22                                           ` Vlad Yasevich
2014-09-11 12:40                                             ` Hannes Frederic Sowa
2014-09-11 12:05                                         ` Hannes Frederic Sowa
2014-09-11 14:19                                           ` Vlad Yasevich
2014-09-11 14:32                                             ` Hannes Frederic Sowa
2014-09-11 14:44                                               ` Vlad Yasevich
2014-09-11 14:47                                                 ` Hannes Frederic Sowa
2014-09-08 15:06               ` [PATCH v2 net-next] tcp: remove dst refcount false sharing for prequeue mode Eric Dumazet
2014-09-08 21:21                 ` David Miller
2014-09-08 21:30                   ` Eric Dumazet
2014-09-08 22:41                     ` David Miller
2014-09-09 23:56                     ` David Miller
2014-08-15 17:15       ` Performance regression on kernels 3.10 and newer Alexander Duyck
2014-08-15 17:59         ` Eric Dumazet
2014-08-15 18:49         ` Tom Herbert
2014-08-15 19:10           ` Alexander Duyck
2014-08-15 22:16             ` Tom Herbert
2014-08-15 23:23               ` Alexander Duyck
2014-08-18  9:03                 ` David Laight
2014-08-18 15:22                   ` Alexander Duyck
2014-08-18 15:29                     ` Rick Jones
2014-08-21 23:51         ` David Miller
2014-08-14 23:48     ` Eric Dumazet
2014-08-15  0:33       ` Rick Jones

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