From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx160.postini.com [74.125.245.160]) by kanga.kvack.org (Postfix) with SMTP id C3DEC6B002C for ; Tue, 31 Jan 2012 21:26:32 -0500 (EST) Subject: Re: [PATCH] fix readahead pipeline break caused by block plug From: Shaohua Li In-Reply-To: <20120131103416.GA1661@localhost> References: <1327996780.21268.42.camel@sli10-conroe> <20120131103416.GA1661@localhost> Content-Type: text/plain; charset="UTF-8" Date: Wed, 01 Feb 2012 10:25:26 +0800 Message-ID: <1328063126.21268.54.camel@sli10-conroe> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Wu Fengguang Cc: lkml , linux-mm , Andrew Morton , Jens Axboe , Herbert Poetzl , Eric Dumazet , Vivek Goyal On Tue, 2012-01-31 at 18:34 +0800, Wu Fengguang wrote: > I'd like to propose a sister patch on the write part. It may not be > as easy to measure any performance impacts of it, but I'll try. I did think about it, the write case doesn't matter because we didn't do real IO there. I can do another patch to cleanup the code (moving it to direct_io), sounds ok? > --- > Subject: remove plugging at buffered write time > Date: Tue Jan 31 18:25:48 CST 2012 > > Buffered write(2) is not directly tied to IO, so no need to handle plug > in generic_file_aio_write(). > > CC: Jens Axboe > CC: Li Shaohua > Signed-off-by: Wu Fengguang > --- > mm/filemap.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > --- linux-next.orig/mm/filemap.c 2012-01-31 18:23:52.000000000 +0800 > +++ linux-next/mm/filemap.c 2012-01-31 18:25:38.000000000 +0800 > @@ -2267,6 +2267,7 @@ generic_file_direct_write(struct kiocb * > struct file *file = iocb->ki_filp; > struct address_space *mapping = file->f_mapping; > struct inode *inode = mapping->host; > + struct blk_plug plug; > ssize_t written; > size_t write_len; > pgoff_t end; > @@ -2301,7 +2302,9 @@ generic_file_direct_write(struct kiocb * > } > } > > + blk_start_plug(&plug); > written = mapping->a_ops->direct_IO(WRITE, iocb, iov, pos, *nr_segs); > + blk_finish_plug(&plug); > > /* > * Finally, try again to invalidate clean pages which might have been > @@ -2610,13 +2613,11 @@ ssize_t generic_file_aio_write(struct ki > { > struct file *file = iocb->ki_filp; > struct inode *inode = file->f_mapping->host; > - struct blk_plug plug; > ssize_t ret; > > BUG_ON(iocb->ki_pos != pos); > > mutex_lock(&inode->i_mutex); > - blk_start_plug(&plug); > ret = __generic_file_aio_write(iocb, iov, nr_segs, &iocb->ki_pos); > mutex_unlock(&inode->i_mutex); > > @@ -2627,7 +2628,6 @@ ssize_t generic_file_aio_write(struct ki > if (err < 0 && ret > 0) > ret = err; > } > - blk_finish_plug(&plug); > return ret; > } > EXPORT_SYMBOL(generic_file_aio_write); -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org