From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 88AB6C10F11 for ; Wed, 24 Apr 2019 18:56:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5E9AD208E4 for ; Wed, 24 Apr 2019 18:56:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727847AbfDXS4I (ORCPT ); Wed, 24 Apr 2019 14:56:08 -0400 Received: from mx2.suse.de ([195.135.220.15]:57194 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727503AbfDXS4I (ORCPT ); Wed, 24 Apr 2019 14:56:08 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 05828AC32; Wed, 24 Apr 2019 18:56:06 +0000 (UTC) Subject: Re: [PATCH] block: use static bio_set for bio_split() calls To: Sagi Grimberg , Ming Lei Cc: Jens Axboe , Hannes Reinecke , Bart van Assche , Ming Lei , neilb@suse.com, linux-nvme@lists.infradead.org, linux-block@vger.kernel.org, Christoph Hellwig References: <20190418140632.60606-1-hare@suse.de> <20190418143429.GA19175@ming.t460p> <98d8549a-2663-b404-e38a-6f55dfb575bf@grimberg.me> From: Hannes Reinecke Message-ID: <69845bdb-cfc6-58d4-4fea-b06c2dd44872@suse.de> Date: Wed, 24 Apr 2019 20:56:05 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.5.1 MIME-Version: 1.0 In-Reply-To: <98d8549a-2663-b404-e38a-6f55dfb575bf@grimberg.me> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On 4/24/19 7:20 PM, Sagi Grimberg wrote: > >> per-queue bioset is used originally for avoiding deadlock, are you >> sure the static bioset is safe? > > Can you explain this? I didn't find any indication of that in the change > log history... > > Originally introduced by Kent: > -- > commit 54efd50bfd873e2dbf784e0b21a8027ba4299a3e > Author: Kent Overstreet > Date:   Thu Apr 23 22:37:18 2015 -0700 > Phew. I was wondering whether I'd been too stupid to find it. And having looked at it a bit closer, moving the bioset into the holding structure would induce more churn, as we'd need to pass the bioset into blk_queue_split(), which would mean to update all drivers (11 in total) for no real gain IMO; bio splitting shouldn't really be a regular occurrence and hence the bioset should only be used infrequently. However, I really would like to get feedback to the actual patch, as this solves a real customer issues we've had (or still have, depending on the view :-) Cheers, Hannes -- Dr. Hannes Reinecke Teamlead Storage & Networking hare@suse.de +49 911 74053 688 SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg GF: Felix Imendörffer, Mary Higgins, Sri Rasiah HRB 21284 (AG Nürnberg) From mboxrd@z Thu Jan 1 00:00:00 1970 From: hare@suse.de (Hannes Reinecke) Date: Wed, 24 Apr 2019 20:56:05 +0200 Subject: [PATCH] block: use static bio_set for bio_split() calls In-Reply-To: <98d8549a-2663-b404-e38a-6f55dfb575bf@grimberg.me> References: <20190418140632.60606-1-hare@suse.de> <20190418143429.GA19175@ming.t460p> <98d8549a-2663-b404-e38a-6f55dfb575bf@grimberg.me> Message-ID: <69845bdb-cfc6-58d4-4fea-b06c2dd44872@suse.de> On 4/24/19 7:20 PM, Sagi Grimberg wrote: > >> per-queue bioset is used originally for avoiding deadlock, are you >> sure the static bioset is safe? > > Can you explain this? I didn't find any indication of that in the change > log history... > > Originally introduced by Kent: > -- > commit 54efd50bfd873e2dbf784e0b21a8027ba4299a3e > Author: Kent Overstreet > Date:?? Thu Apr 23 22:37:18 2015 -0700 > Phew. I was wondering whether I'd been too stupid to find it. And having looked at it a bit closer, moving the bioset into the holding structure would induce more churn, as we'd need to pass the bioset into blk_queue_split(), which would mean to update all drivers (11 in total) for no real gain IMO; bio splitting shouldn't really be a regular occurrence and hence the bioset should only be used infrequently. However, I really would like to get feedback to the actual patch, as this solves a real customer issues we've had (or still have, depending on the view :-) Cheers, Hannes -- Dr. Hannes Reinecke Teamlead Storage & Networking hare at suse.de +49 911 74053 688 SUSE LINUX GmbH, Maxfeldstr. 5, 90409 N?rnberg GF: Felix Imend?rffer, Mary Higgins, Sri Rasiah HRB 21284 (AG N?rnberg)