From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id AF22E2BE637; Wed, 2 Jul 2025 18:52:14 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1751482334; cv=none; b=Ry1OHr/FHjJAhnuc14Ex7zeyLmDstYCzNwI1JC/Tv657k9UnqmMjvLOQ+49GmcrvwgL5KCxKRcjUhYZ4R9s0+IkAbbb0H/gRjq8HcgBYAdMbvqmGSOMbYeueU7x3tCmemsUQDrPJJ4wIStwX3fHw7SW6lfGV4Vqk7U1eQYyIGek= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1751482334; c=relaxed/simple; bh=OHk7XwglHJcDWN72KQjJUAxP0PTjfem32WqdpZA4khw=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=QrVl8fHwmUW/pAlCL1tOPelG2s6E2aDcWwvACJ6ch5vUNbrN+9+MWxKaSxvkzsWwMxvzrCLN/4XRubaiL8xRb4GPRMwwQ1ylpa2YyqB3vQBy4C1GnN5dBFWFXok8vHl0LRaV1QT5LgXoX5Js4Sk3e1ce9xFjgrvFKm15+TqXfk8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=iM0ZzfxT; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="iM0ZzfxT" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 45663C4CEE7; Wed, 2 Jul 2025 18:52:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1751482334; bh=OHk7XwglHJcDWN72KQjJUAxP0PTjfem32WqdpZA4khw=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=iM0ZzfxT+xq4GpA8fIVxugSeI1LBwGsjeitUjYcIA3//vGtGY55runcEoY+NiyKTy mxyi4kjHC+c7Tfgn2FJPDORAOzvmdpD53Za2drdZPFidSFt4h4roFGhyBVmoA2HEmo wSja+nZwAH0djf2ev2tfvFTvHFemJFVVGQnkoeWLJ+39aYOt6VxB3IcGpUl5Ay5TfA uFWP9Fya+UYH8gBqoZTvxzX1E7luxDgqnCh9ZPOmMJD8eOcppnI4U8liL5K3Xvizfl ieMrUgCf9gIXRBhBLPMqz37iHtde2UPEXO6o+iU7zo7Kv/GExbXDfEJ4fUwMCIIRuD ng+Cf3ERhd2fA== Date: Wed, 2 Jul 2025 11:52:13 -0700 From: "Darrick J. Wong" To: Jinliang Zheng Cc: alexjlzheng@tencent.com, brauner@kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-xfs@vger.kernel.org Subject: Re: [PATCH] iomap: avoid unnecessary ifs_set_range_uptodate() with locks Message-ID: <20250702185213.GY10009@frogsfrogsfrogs> References: <20250701184737.GA9991@frogsfrogsfrogs> <20250702120912.36380-1-alexjlzheng@tencent.com> Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250702120912.36380-1-alexjlzheng@tencent.com> On Wed, Jul 02, 2025 at 08:09:12PM +0800, Jinliang Zheng wrote: > On Tue, 1 Jul 2025 11:47:37 -0700, djwong@kernel.org wrote: > > On Tue, Jul 03, 2025 at 10:48:47PM +0800, alexjlzheng@gmail.com wrote: > > > From: Jinliang Zheng > > > > > > In the buffer write path, iomap_set_range_uptodate() is called every > > > time iomap_end_write() is called. But if folio_test_uptodate() holds, we > > > know that all blocks in this folio are already in the uptodate state, so > > > there is no need to go deep into the critical section of state_lock to > > > execute bitmap_set(). > > > > > > Although state_lock may not have significant lock contention due to > > > folio lock, this patch at least reduces the number of instructions. > > > > > > Signed-off-by: Jinliang Zheng > > > --- > > > fs/iomap/buffered-io.c | 3 +++ > > > 1 file changed, 3 insertions(+) > > > > > > diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c > > > index 3729391a18f3..fb4519158f3a 100644 > > > --- a/fs/iomap/buffered-io.c > > > +++ b/fs/iomap/buffered-io.c > > > @@ -71,6 +71,9 @@ static void iomap_set_range_uptodate(struct folio *folio, size_t off, > > > unsigned long flags; > > > bool uptodate = true; > > > > > > + if (folio_test_uptodate(folio)) > > > + return; > > > > Looks fine, but how exhaustively have you tested this with heavy IO > > workloads? I /think/ it's the case that folios always creep towards > > ifs_is_fully_uptodate() == true state and once they've gotten there > > never go back. But folio state bugs are tricky to detect once they've > > crept in. > > I tested fio, ltp and xfstests combined for about 30 hours. The command > used for fio test is: > > fio --name=4k-rw \ > --filename=/data2/testfile \ > --size=1G \ > --bs=4096 \ > --ioengine=libaio \ > --iodepth=32 \ > --rw=randrw \ > --direct=0 \ > --buffered=1 \ > --numjobs=16 \ > --runtime=60 \ > --time_based \ > --group_reporting > > ltp and xfstests showed no noticeable errors caused by this patch. I think this fine then... Reviewed-by: "Darrick J. Wong" --D > > thanks, > Jinliang Zheng. :) > > > > > --D > > > > > + > > > if (ifs) { > > > spin_lock_irqsave(&ifs->state_lock, flags); > > > uptodate = ifs_set_range_uptodate(folio, ifs, off, len); > > > -- > > > 2.49.0 > > > > > > >