From: David Howells <dhowells@redhat.com>
To: Nick Piggin <npiggin@suse.de>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Andi Kleen <ak@suse.de>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Linux Memory Management List <linux-mm@kvack.org>,
Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [patch] generic rwsems
Date: Fri, 13 Apr 2007 12:44:50 +0100 [thread overview]
Message-ID: <25428.1176464690@redhat.com> (raw)
In-Reply-To: <20070413102518.GD31487@wotan.suse.de>
Nick Piggin <npiggin@suse.de> wrote:
> I think I should put wait_lock after wait_list, so as to get a better
> packing on most 64-bit architectures.
It makes no difference. struct lockdep_map contains at least one pointer and
so is going to be 8-byte aligned (assuming it's there at all). struct
rw_semaphore contains at least one pointer/long, so it will be padded out to
8-byte size.
If you want to make a difference, you'd need to add __attribute__((packed))
but you would need to be very careful with that.
David
WARNING: multiple messages have this Message-ID (diff)
From: David Howells <dhowells@redhat.com>
To: Nick Piggin <npiggin@suse.de>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Andi Kleen <ak@suse.de>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Linux Memory Management List <linux-mm@kvack.org>,
Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [patch] generic rwsems
Date: Fri, 13 Apr 2007 12:44:50 +0100 [thread overview]
Message-ID: <25428.1176464690@redhat.com> (raw)
In-Reply-To: <20070413102518.GD31487@wotan.suse.de>
Nick Piggin <npiggin@suse.de> wrote:
> I think I should put wait_lock after wait_list, so as to get a better
> packing on most 64-bit architectures.
It makes no difference. struct lockdep_map contains at least one pointer and
so is going to be 8-byte aligned (assuming it's there at all). struct
rw_semaphore contains at least one pointer/long, so it will be padded out to
8-byte size.
If you want to make a difference, you'd need to add __attribute__((packed))
but you would need to be very careful with that.
David
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next prev parent reply other threads:[~2007-04-13 11:45 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-04-13 10:04 [patch] generic rwsems Nick Piggin
2007-04-13 10:04 ` Nick Piggin
2007-04-13 10:19 ` fastcalls, was " Christoph Hellwig
2007-04-13 10:59 ` Nick Piggin
2007-04-13 10:25 ` Nick Piggin
2007-04-13 10:25 ` Nick Piggin
2007-04-13 11:44 ` David Howells [this message]
2007-04-13 11:44 ` David Howells
2007-04-13 12:13 ` Christoph Hellwig
2007-04-13 12:13 ` Christoph Hellwig
2007-04-13 10:53 ` Andi Kleen
2007-04-13 10:53 ` Andi Kleen
2007-04-13 11:20 ` Nick Piggin
2007-04-13 11:20 ` Nick Piggin
2007-04-13 12:09 ` David Howells
2007-04-13 12:09 ` David Howells
2007-04-13 12:43 ` Nick Piggin
2007-04-13 12:43 ` Nick Piggin
2007-04-13 13:22 ` William Lee Irwin III
2007-04-13 13:22 ` William Lee Irwin III
2007-04-13 13:31 ` David Howells
2007-04-13 13:31 ` David Howells
2007-04-13 14:03 ` Nick Piggin
2007-04-13 14:03 ` Nick Piggin
2007-04-13 14:29 ` Eric Dumazet
2007-04-13 14:29 ` Eric Dumazet
2007-04-13 14:49 ` David Howells
2007-04-13 14:49 ` David Howells
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