From: Andi Kleen <ak@muc.de>
To: "David S. Miller" <davem@redhat.com>
Cc: akpm@digeo.com, willy@debian.org, ak@muc.de,
linux-kernel@vger.kernel.org, anton@samba.org,
schwidefsky@de.ibm.com, davidm@hpl.hp.com, matthew@wil.cx,
ralf@linux-mips.org, rth@redhat.com
Subject: Re: Reduce struct page by 8 bytes on 64bit
Date: Thu, 17 Apr 2003 17:20:21 +0200 [thread overview]
Message-ID: <20030417172021.41103@colin.muc.de> (raw)
In-Reply-To: <20030416.144035.130217416.davem@redhat.com>; from David S. Miller on Wed, Apr 16, 2003 at 11:40:35PM +0200
On Wed, Apr 16, 2003 at 11:40:35PM +0200, David S. Miller wrote:
> From: Andrew Morton <akpm@digeo.com>
> Date: Wed, 16 Apr 2003 14:43:11 -0700
>
> Well are we sure that the `flags' and `count' fields will always fall into
> the same 256-byte range? Wouldn't it subtly break if sizeof(struct page)
> became not a multiple of eight? Will the compiler pad it out anyway?
>
> As long as there is a long or pointer member, the structure
> will be required to be 8 byte or better aligned.
Yes that should be a safe assumption. mem_map will be always page aligned
and it should be a multiple of a power of 8. That makes it impossible for it
to cross a cache line.
-Andi
prev parent reply other threads:[~2003-04-17 15:09 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-04-15 11:24 Reduce struct page by 8 bytes on 64bit Andi Kleen
2003-04-16 12:45 ` David S. Miller
2003-04-16 13:22 ` Jakub Jelinek
2003-04-16 14:07 ` Andi Kleen
2003-04-16 14:26 ` David S. Miller
2003-04-16 14:43 ` Andi Kleen
2003-04-16 14:38 ` David S. Miller
2003-04-16 14:58 ` Andi Kleen
2003-04-16 14:58 ` David S. Miller
2003-04-16 14:55 ` Matthew Wilcox
2003-04-16 15:04 ` Andi Kleen
2003-04-16 15:00 ` David S. Miller
2003-04-16 15:11 ` Matthew Wilcox
2003-04-16 20:35 ` Andrew Morton
2003-04-16 21:26 ` Matthew Wilcox
2003-04-16 21:43 ` Andrew Morton
2003-04-16 21:40 ` David S. Miller
2003-04-17 15:20 ` Andi Kleen [this message]
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