From: Nick Piggin <nickpiggin@yahoo.com.au>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: David Howells <dhowells@redhat.com>,
torvalds@linux-foundation.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] AFS: Fix file locking
Date: Wed, 18 Jul 2007 15:56:53 +1000 [thread overview]
Message-ID: <469DABA5.9070706@yahoo.com.au> (raw)
In-Reply-To: <20070717175017.8b8a8976.akpm@linux-foundation.org>
Andrew Morton wrote:
> On Tue, 17 Jul 2007 13:47:32 +0100
> David Howells <dhowells@redhat.com> wrote:
>
>
>>+ if (type == AFS_LOCK_READ &&
>>+ vnode->flags & (1 << AFS_VNODE_READLOCKED)) {
>
>
> Here we use
>
> vnode->flags & (1 << foo)
>
>
>>+ set_bit(AFS_VNODE_LOCKING, &vnode->flags);
>
>
> and elsewhere we use set_bit(foo, &vnode->flags) and clear_bit()
>
> This is a bit strange. Does the open-coded bit-test have any performance
> benefit on any architecture? Not on x86 at least, afaik.
It uses locked operations on x86, but you can use __set_bit instead
(which should always be at least as efficient as the C version).
--
SUSE Labs, Novell Inc.
next prev parent reply other threads:[~2007-07-20 2:03 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-07-17 12:47 [PATCH] AFS: Fix file locking David Howells
2007-07-18 0:50 ` Andrew Morton
2007-07-18 5:56 ` Nick Piggin [this message]
2007-07-20 3:41 ` Andrew Morton
2007-07-20 4:59 ` Nick Piggin
2007-07-21 1:37 ` Linus Torvalds
2007-07-23 7:07 ` Nick Piggin
2007-07-23 8:50 ` Satyam Sharma
2007-07-23 9:13 ` Satyam Sharma
2007-07-23 9:13 ` David Howells
2007-07-18 9:23 ` David Howells
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