From: Nick Piggin <nickpiggin@yahoo.com.au>
To: Andrew Morton <akpm@osdl.org>
Cc: axboe@suse.de, lkml <linux-kernel@vger.kernel.org>
Subject: Re: [patch] optimise loop driver a bit
Date: Tue, 26 Apr 2005 22:12:47 +1000 [thread overview]
Message-ID: <1114517567.5097.30.camel@npiggin-nld.site> (raw)
In-Reply-To: <20050426050429.69137417.akpm@osdl.org>
On Tue, 2005-04-26 at 05:04 -0700, Andrew Morton wrote:
> Nick Piggin <nickpiggin@yahoo.com.au> wrote:
> >
> > Looks like locking can be optimised quite a lot.
>
> So I've peered suspiciously at the ->lo_pending handling for some time and
> am unconvinced. Are you sure that the error path in loop_make_request() is
> correct? The old code decremented the pending count in there.
>
Pretty sure it is correct. I'm usually wrong though :P
It decremented lo_pending because it had previously incremented it.
We do away with that and do that under a single critical section,
with the increment done _after_ all error checking. So...
> Why do we need that nasty-looking `pending' local in loop_thread()?
Don't I guess, no. If it reaches zero at any stage then that's
where it should stay. So I think you can just read lo_pending.
Nick
--
SUSE Labs, Novell Inc.
prev parent reply other threads:[~2005-04-26 12:12 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-04-25 3:58 Nick Piggin
2005-04-26 12:04 ` Andrew Morton
2005-04-26 12:12 ` Nick Piggin [this message]
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