From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Morton Subject: Re: [RESEND][PATCH v2] block: remove plugging at buffered write time Date: Wed, 11 Apr 2012 16:13:44 -0700 Message-ID: <20120411161344.309f12ef.akpm@linux-foundation.org> References: <20120408010600.GA31377@localhost> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: Wu Fengguang , Jens Axboe , linux-fsdevel@vger.kernel.org, LKML , Dave Chinner , Christoph Hellwig , Jan Kara , Chris Mason , Shaohua Li To: Jeff Moyer Return-path: In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org On Mon, 09 Apr 2012 10:34:44 -0400 Jeff Moyer wrote: > Wu Fengguang writes: > > > Buffered write(2) is not directly tied to IO, so it's not suitable to > > handle plug in generic_file_aio_write(). > [snip, moved] > > Note that plugging for O_SYNC writes is also removed. The user may pass > > arbitrary @size arguments, which may be much larger than the preferable > > I/O size, or may cross extent/device boundaries. Let the lower layers > > handle the plugging. Otherwise the plugging code here will turn the > > low level plugging into no-ops. > > I assume you have some numbers to back this up, right? Care to share > those? Yes please. We've broken this stuff a few times recently - we should review and test carefully. > > Also moves unplugging for direct I/O from around ->direct_IO() down to > > do_blockdev_direct_IO(). > > This could be handled in a separate patch. I think that would be better.