From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753013AbbAUH4p (ORCPT ); Wed, 21 Jan 2015 02:56:45 -0500 Received: from aserp1040.oracle.com ([141.146.126.69]:40393 "EHLO aserp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752838AbbAUH4a (ORCPT ); Wed, 21 Jan 2015 02:56:30 -0500 From: Bob Liu To: xen-devel@lists.xen.org Cc: david.vrabel@citrix.com, linux-kernel@vger.kernel.org, roger.pau@citrix.com, konrad.wilk@oracle.com, Bob Liu Subject: [RESEND PATCH] xen/blkfront: increase the default value of xen_blkif_max_segments Date: Wed, 21 Jan 2015 15:56:03 +0800 Message-Id: <1421826963-6497-1-git-send-email-bob.liu@oracle.com> X-Mailer: git-send-email 1.7.10.4 X-Source-IP: acsinet21.oracle.com [141.146.126.237] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The default max-segments of indirect requests was 32, so IO operations with bigger block size(>32*4k) would be split and make performance drop. Nowadays backend device usually support 512k max_sectors_kb on desktop, and usually larger on server machines connected with high-end storage system. The default max size(128k) is not appropriate anymore, this patch increases it to 128(128*4k=512k). Signed-off-by: Bob Liu --- drivers/block/xen-blkfront.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c index 2236c6f..1bf2429 100644 --- a/drivers/block/xen-blkfront.c +++ b/drivers/block/xen-blkfront.c @@ -94,9 +94,9 @@ static const struct block_device_operations xlvbd_block_fops; * by the backend driver. */ -static unsigned int xen_blkif_max_segments = 32; +static unsigned int xen_blkif_max_segments = 128; module_param_named(max, xen_blkif_max_segments, int, S_IRUGO); -MODULE_PARM_DESC(max, "Maximum amount of segments in indirect requests (default is 32)"); +MODULE_PARM_DESC(max, "Maximum amount of segments in indirect requests (default is 128)"); #define BLK_RING_SIZE __CONST_RING_SIZE(blkif, PAGE_SIZE) -- 1.7.10.4