From: Andi Kleen <andi@firstfloor.org>
To: Eric Dumazet <dada1@cosmosbay.com>
Cc: David Miller <davem@davemloft.net>,
andi@firstfloor.org, davej@redhat.com, netdev@vger.kernel.org,
j.w.r.degoede@hhs.nl
Subject: Re: cat /proc/net/tcp takes 0.5 seconds on x86_64
Date: Thu, 28 Aug 2008 09:45:36 +0200 [thread overview]
Message-ID: <20080828074536.GK26610@one.firstfloor.org> (raw)
In-Reply-To: <48B5F3E2.2000909@cosmosbay.com>
> When scanning route cache hash table, we can avoid taking locks for empty
> buckets.
I'm not sure it's worth it in this case. A rcu_read_lock() is a nop
(on non preemptible kernel) to very cheap (non atomic increment/decrement in
cached task_struct)
If you really wanted to make it faster I think a better strategy
would be to not take it every bucket, but maybe only every 100th
or so. That would still keep preempt off times reasonably low, but
even help when the table is filled. But not sure it would
be even measurable, really it should be quite cheap.
-Andi
next prev parent reply other threads:[~2008-08-28 7:43 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <bug-459782-176318@bugzilla.redhat.com>
[not found] ` <200808261549.m7QFnVUN032543@bz-web1.app.phx.redhat.com>
2008-08-26 16:37 ` cat /proc/net/tcp takes 0.5 seconds on x86_64 Dave Jones
2008-08-26 18:32 ` Eric Dumazet
2008-08-26 19:01 ` Hans de Goede
2008-08-26 20:39 ` Eric Dumazet
2008-08-26 20:58 ` Hans de Goede
2008-08-26 21:27 ` Eric Dumazet
2008-08-27 9:14 ` Hans de Goede
2008-08-27 9:05 ` David Miller
2008-08-27 9:45 ` Hans de Goede
2008-08-27 9:39 ` David Miller
2008-08-27 4:19 ` Herbert Xu
2008-08-27 9:07 ` Hans de Goede
2008-08-27 12:41 ` Andi Kleen
2008-08-27 21:29 ` Trent Piepho
2008-08-27 21:47 ` Andi Kleen
2008-08-27 22:54 ` Andi Kleen
2008-08-27 21:29 ` David Miller
2008-08-27 21:48 ` Stephen Hemminger
2008-08-27 22:09 ` David Miller
2008-08-28 6:20 ` Eric Dumazet
2008-08-28 6:51 ` David Miller
2008-08-28 7:13 ` Eric Dumazet
2008-08-28 7:57 ` David Miller
2008-08-28 9:52 ` Eric Dumazet
2008-08-28 7:26 ` Andi Kleen
2008-08-27 22:34 ` Andi Kleen
2008-08-27 22:39 ` David Miller
2008-08-27 22:57 ` Andi Kleen
2008-08-27 23:07 ` David Miller
2008-08-27 23:09 ` Eric Dumazet
2008-08-27 23:15 ` David Miller
2008-08-27 23:35 ` Andi Kleen
2008-08-27 23:43 ` Eric Dumazet
2008-08-27 23:45 ` David Miller
2008-08-28 0:40 ` Eric Dumazet
2008-08-28 7:45 ` Andi Kleen [this message]
2008-08-28 7:59 ` David Miller
2008-08-28 8:12 ` Hans de Goede
2008-08-28 8:04 ` David Miller
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