From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754323AbbFONDg (ORCPT ); Mon, 15 Jun 2015 09:03:36 -0400 Received: from mail-wi0-f177.google.com ([209.85.212.177]:38225 "EHLO mail-wi0-f177.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752083AbbFOND1 (ORCPT ); Mon, 15 Jun 2015 09:03:27 -0400 MIME-Version: 1.0 In-Reply-To: <557EB47F.6090708@unitedstack.com> References: <557EB47F.6090708@unitedstack.com> Date: Mon, 15 Jun 2015 16:03:25 +0300 Message-ID: Subject: Re: [PATCH RFC] storage:rbd: make the size of request is equal to the, size of the object From: Ilya Dryomov To: juncheng bai Cc: idryomov@redhat.com, Alex Elder , Josh Durgin , lucienchao@gmail.com, jeff@garzik.org, yehuda@hq.newdream.net, Sage Weil , elder@inktank.com, "linux-kernel@vger.kernel.org" , Ceph Development Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jun 15, 2015 at 2:18 PM, juncheng bai wrote: > From 6213215bd19926d1063d4e01a248107dab8a899b Mon Sep 17 00:00:00 2001 > From: juncheng bai > Date: Mon, 15 Jun 2015 18:34:00 +0800 > Subject: [PATCH] storage:rbd: make the size of request is equal to the > size of the object > > ensures that the merged size of request can achieve the size of > the object. > when merge a bio to request or merge a request to request, the > sum of the segment number of the current request and the segment > number of the bio is not greater than the max segments of the request, > so the max size of request is 512k if the max segments of request is > BLK_MAX_SEGMENTS. > > Signed-off-by: juncheng bai > --- > drivers/block/rbd.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c > index 0a54c58..dec6045 100644 > --- a/drivers/block/rbd.c > +++ b/drivers/block/rbd.c > @@ -3757,6 +3757,8 @@ static int rbd_init_disk(struct rbd_device *rbd_dev) > segment_size = rbd_obj_bytes(&rbd_dev->header); > blk_queue_max_hw_sectors(q, segment_size / SECTOR_SIZE); > blk_queue_max_segment_size(q, segment_size); > + if (segment_size > BLK_MAX_SEGMENTS * PAGE_SIZE) > + blk_queue_max_segments(q, segment_size / PAGE_SIZE); > blk_queue_io_min(q, segment_size); > blk_queue_io_opt(q, segment_size); I made a similar patch on Friday, investigating blk-mq plugging issue reported by Nick. My patch sets it to BIO_MAX_PAGES unconditionally - AFAIU there is no point in setting to anything bigger since the bios will be clipped to that number of vecs. Given that BIO_MAX_PAGES is 256, this gives is 1M direct I/Os. Thanks, Ilya