From: Matt Mackall <mpm@selenic.com>
To: Arnaldo Carvalho de Melo <acme@redhat.com>, linux-kernel@vger.kernel.org
Subject: Re: [RFC] Reorganizing structs to save space
Date: Tue, 3 Apr 2007 16:30:29 -0500 [thread overview]
Message-ID: <20070403213028.GV10459@waste.org> (raw)
In-Reply-To: <20070403122848.GA14224@ghostprotocols.net>
On Tue, Apr 03, 2007 at 09:28:48AM -0300, Arnaldo Carvalho de Melo wrote:
> module 16960 16848 112
That's huge.
> struct module_ref ref[255]; /* 480 16320 */
Huh. That's this:
struct module_ref
{
local_t count;
} ____cacheline_aligned;
This is horrible. Surely there's some way to do better than a
cacheline per module per possible CPU. We should only need 4 bytes per
module per online CPU.
And really, about the only case where we actually care about cacheline
bouncing here at all is on modules that do this per-packet. Just about
everyone else can get by with 4 bytes per module total.
--
Mathematics is the supreme nostalgia of our time.
prev parent reply other threads:[~2007-04-03 21:43 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-04-03 12:28 [RFC] Reorganizing structs to save space Arnaldo Carvalho de Melo
2007-04-03 21:30 ` Matt Mackall [this message]
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