From: David Miller <davem@davemloft.net>
To: ak@suse.de
Cc: dada1@cosmosbay.com, linux@horizon.com, akepner@sgi.com,
netdev@vger.kernel.org
Subject: Re: [PATCH] NET : change layout of ehash table
Date: Fri, 09 Feb 2007 00:40:19 -0800 (PST) [thread overview]
Message-ID: <20070209.004019.75431263.davem@davemloft.net> (raw)
In-Reply-To: <p73zm7n1ygk.fsf@bingen.suse.de>
From: Andi Kleen <ak@suse.de>
Date: 09 Feb 2007 10:18:03 +0100
> David Miller <davem@davemloft.net> writes:
> >
> > I've applied this, but I _REALLY_ don't like the new multiply
> > instructions that are used now in the hash indexing paths when
> > CONFIG_SMP is set.
> >
> > I think that's a higher cost than the memory waste.
>
> You're serious? multiply on a modern CPU is _much_ cheaper than a cache miss
> e.g. a K8 can do a arbitary 64bit multiplication in 3-7 cycles.
> Any cache miss will be in the three to four digits at least.
I'm not thinking of modern CPUs, I'm think of the little
guys :-)
next prev parent reply other threads:[~2007-02-09 8:40 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-12-19 8:56 [PATCH] irlan: handle out of memory errors Akinobu Mita
2006-12-19 22:47 ` Samuel Ortiz
2007-02-07 8:12 ` David Miller
2007-02-07 10:59 ` [PATCH] NET : change layout of ehash table Eric Dumazet
2007-02-08 22:56 ` David Miller
2007-02-09 9:18 ` Andi Kleen
2007-02-09 8:40 ` David Miller [this message]
2007-02-09 8:57 ` Andi Kleen
2007-02-09 9:06 ` Eric Dumazet
2007-02-09 9:15 ` David Miller
2007-02-09 9:36 ` Eric Dumazet
2007-02-09 9:43 ` David Miller
2007-02-09 10:10 ` Andi Kleen
2007-02-09 17:44 ` [PATCH] NET : UDP can use sk_hash to speedup lookups Eric Dumazet
2007-02-09 23:45 ` David Miller
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