Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751815AbbKONQy (ORCPT ); Sun, 15 Nov 2015 08:16:54 -0500 Received: from mail-wm0-f51.google.com ([74.125.82.51]:38182 "EHLO mail-wm0-f51.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751335AbbKONQu (ORCPT ); Sun, 15 Nov 2015 08:16:50 -0500 Subject: Re: [PATCH 1/9] move blk_iopoll to limit and make it generally available To: Or Gerlitz References: <1447422410-20891-1-git-send-email-hch@lst.de> <1447422410-20891-2-git-send-email-hch@lst.de> <20151114070200.GA27738@lst.de> <564846E9.9070301@dev.mellanox.co.il> Cc: Christoph Hellwig , "linux-rdma@vger.kernel.org" , Bart Van Assche , axboe@fb.com, "linux-scsi@vger.kernel.org" , Linux Kernel , Oren Duer From: Sagi Grimberg Message-ID: <564885BE.1080707@dev.mellanox.co.il> Date: Sun, 15 Nov 2015 15:16:46 +0200 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:38.0) Gecko/20100101 Thunderbird/38.3.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1729 Lines: 48 On 15/11/2015 11:04, Or Gerlitz wrote: > On Sun, Nov 15, 2015 at 10:48 AM, Sagi Grimberg > wrote: >> Or is correct, >> >> I have attempted to convert iser to use blk_iopoll in the past, however >> I've seen inconsistent performance and latency skews (comparing to >> tasklets iser is using today). This was manifested in IOPs test cases >> where I ran multiple threads with higher queue-depth and not in >> sanitized pure latency (QD=1) test cases. Unfortunately I didn't have >> the time to pick it up since. >> >> I do have every intention of testing it again with this. If it still >> exist we will need to find the root-cause of it before converting >> drivers to use it. > > Good, this way (inconsistent performance and latency skews) or another > (all shines up) -- please > let us know your findings, best through commenting within V > 0 the > cover letter posts of this series > Hi Or & Co, I ran some tests on the iser code with this patchset applied. I can confirm that I did not see any performance degradations. summary (on my test servers): 1 LUN: ~530K (IOPs) 2 LUNs: ~1080K (IOPs) 4 LUNs: ~1350K (IOPs) 8 LUNs: ~1930K (IOPs) 16 LUns: ~2250K (IOPs) These results are true both for tasklet and iopoll. So, I don't have anything smart to say here, the IO stack (block, scsi) has gone through major changes since the last time I looked into this, so it'll be pretty hard to figure out what was the root cause back then... Sagi. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/