From: Eric Dumazet <dada1@cosmosbay•com>
To: "David S. Miller" <davem@davemloft•net>
Cc: netdev@oss•sgi.com
Subject: Re: [PATCH] Add prefetches in net/ipv4/route.c
Date: Thu, 28 Jul 2005 22:56:32 +0200 [thread overview]
Message-ID: <42E94680.8060309@cosmosbay.com> (raw)
In-Reply-To: <20050728.123922.126777020.davem@davemloft.net>
David S. Miller a écrit :
> From: Eric Dumazet <dada1@cosmosbay•com>
> Date: Thu, 28 Jul 2005 17:52:04 +0200
>
>
>>[NET] : Adds prefetches in route hash list traversals.
>>
>>The actual code doesnt use a prefetch enabled macro like
>>list_for_each_rcu(), so manually add prefetch() hints.
>
>
> and the measured performance improvement is?
>
>
Half the improvement we could get if only fl.fl4_dst, and other fields were not so far away from the u.rt_next field. (0xE8 on x86_64)
For good performance, one should of course choose a big route cache hash size, and in this case, prefetchs are useless, and even cost an
extra load : prefetch(rth->u.rt_next) imply the load of the rt_next pointer at the start of rth structure, while the fl fields are on a
different cache line)
But in case of DDOS, prefetches are a win.
I did not test a solution using two prefetches...
Other patches using prefetches will follow.
Eric
next prev parent reply other threads:[~2005-07-28 20:56 UTC|newest]
Thread overview: 63+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-05-11 21:15 [TG3]: Add hw coalescing infrastructure David S. Miller
2005-05-11 21:17 ` Michael Chan
2005-05-12 2:28 ` David S. Miller
2005-05-12 7:53 ` Robert Olsson
2005-06-22 15:25 ` [TG3]: About " Eric Dumazet
2005-06-22 19:03 ` Michael Chan
2005-07-04 21:22 ` Eric Dumazet
2005-07-04 21:26 ` David S. Miller
2005-07-04 21:39 ` Eric Dumazet
2005-07-04 21:49 ` David S. Miller
2005-07-04 22:31 ` Eric Dumazet
2005-07-04 22:47 ` David S. Miller
2005-07-04 22:55 ` Eric Dumazet
2005-07-04 22:57 ` Eric Dumazet
2005-07-04 23:01 ` David S. Miller
2005-07-05 7:38 ` [PATCH] loop unrolling in net/sched/sch_generic.c Eric Dumazet
2005-07-05 11:51 ` Thomas Graf
2005-07-05 12:03 ` Thomas Graf
2005-07-05 13:04 ` Eric Dumazet
2005-07-05 13:48 ` Thomas Graf
2005-07-05 15:58 ` Eric Dumazet
2005-07-05 17:34 ` Thomas Graf
2005-07-05 21:22 ` David S. Miller
2005-07-05 21:33 ` Thomas Graf
2005-07-05 21:35 ` David S. Miller
2005-07-05 23:16 ` Eric Dumazet
2005-07-05 23:41 ` Thomas Graf
2005-07-05 23:45 ` David S. Miller
2005-07-05 23:55 ` Thomas Graf
2005-07-06 0:32 ` Eric Dumazet
2005-07-06 0:51 ` Thomas Graf
2005-07-06 1:04 ` Eric Dumazet
2005-07-06 1:07 ` Thomas Graf
2005-07-06 0:53 ` Eric Dumazet
2005-07-06 1:02 ` Thomas Graf
2005-07-06 1:09 ` Eric Dumazet
2005-07-06 12:42 ` Thomas Graf
2005-07-07 21:17 ` David S. Miller
2005-07-07 21:34 ` Thomas Graf
2005-07-07 22:24 ` David S. Miller
[not found] ` <42CE22CE.7030902@cosmosbay.com>
2005-07-08 7:30 ` David S. Miller
2005-07-08 8:19 ` Eric Dumazet
2005-07-08 11:08 ` Arnaldo Carvalho de Melo
2005-07-12 4:02 ` David S. Miller
2005-07-05 21:26 ` David S. Miller
2005-07-28 15:52 ` [PATCH] Add prefetches in net/ipv4/route.c Eric Dumazet
2005-07-28 19:39 ` David S. Miller
2005-07-28 20:56 ` Eric Dumazet [this message]
2005-07-28 20:58 ` David S. Miller
2005-07-28 21:24 ` Eric Dumazet
2005-07-28 22:44 ` David S. Miller
2005-07-29 14:50 ` Robert Olsson
2005-07-29 17:06 ` Rick Jones
2005-07-29 17:44 ` Robert Olsson
2005-07-29 17:57 ` Eric Dumazet
2005-07-29 18:25 ` Rick Jones
2005-07-31 3:52 ` David S. Miller
[not found] ` <42EDDA50.4010405@cosmosbay.com>
2005-08-01 15:39 ` David S. Miller
2005-07-31 3:51 ` David S. Miller
2005-07-31 3:44 ` David S. Miller
2005-07-04 23:00 ` [TG3]: About hw coalescing infrastructure David S. Miller
2005-07-05 16:14 ` Eric Dumazet
2005-07-04 22:47 ` Eric Dumazet
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