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=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=no 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 16333C433E0 for ; Tue, 2 Feb 2021 20:49:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B664164F61 for ; Tue, 2 Feb 2021 20:49:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231768AbhBBUtZ (ORCPT ); Tue, 2 Feb 2021 15:49:25 -0500 Received: from mx2.suse.de ([195.135.220.15]:45704 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231343AbhBBUtX (ORCPT ); Tue, 2 Feb 2021 15:49:23 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1612298917; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=0AiDbdfvkfioMr2lwDiljufHKju9PMRRBj3UXL4HZ2U=; b=nrHj8GcFkfQdsyTjYI9IYx075zehjRRb2DXRpxDq3ytCLklOvbtmSrfVn19cgn+YQEDsV5 gGoCiQfdpGlSJM/Rf5vy9pzevfhcegcFgJ0VSaBKkhyWNPocsxt/Du5/OSa7qsio6tD5RT uwCioXQBLJZsz6w/zguP5+ISrtZhzXE= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id EFC5BAC55; Tue, 2 Feb 2021 20:48:36 +0000 (UTC) Message-ID: <2e4cca87aaa27220e186025573ae7c24579e8b7b.camel@suse.com> Subject: Re: [PATCH] scsi: scsi_host_queue_ready: increase busy count early From: Martin Wilck To: Don.Brace@microchip.com, john.garry@huawei.com, buczek@molgen.mpg.de, martin.petersen@oracle.com, ming.lei@redhat.com Cc: jejb@linux.vnet.ibm.com, linux-scsi@vger.kernel.org, hare@suse.de, Kevin.Barnett@microchip.com, pmenzel@molgen.mpg.de, hare@suse.com Date: Tue, 02 Feb 2021 21:48:35 +0100 In-Reply-To: References: <20210120184548.20219-1-mwilck@suse.com> <37579c64-1cdb-8864-6a30-4d912836f28a@huawei.com> <231d9fcd-14f4-6abf-c41a-56315877a3dc@molgen.mpg.de> <87b7f873-46c4-140b-ee45-f724b50b6aca@huawei.com> <361d5a2f-fb8e-c400-2818-29aea435aff2@huawei.com> Content-Type: text/plain; charset="ISO-8859-15" User-Agent: Evolution 3.38.2 MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-scsi@vger.kernel.org On Tue, 2021-02-02 at 20:04 +0000, Don.Brace@microchip.com wrote: > -----Original Message----- > From: John Garry [mailto:john.garry@huawei.com] > Subject: Re: [PATCH] scsi: scsi_host_queue_ready: increase busy count > early > > > Confirmed my suspicions - it looks like the host is sent more > commands than it can handle. We would need many disks to see this > issue though, which you have. > > So for stable kernels, 6eb045e092ef is not in 5.4 . Next is 5.10, and > I suppose it could be simply fixed by setting .host_tagset in scsi > host template there. > > Thanks, > John > -- > Don: Even though this works for current kernels, what would chances > of this getting back-ported to 5.9 or even further? > > Otherwise the original patch smartpqi_fix_host_qdepth_limit would > correct this issue for older kernels. True. However this is 5.12 material, so we shouldn't be bothered by that here. For 5.5 up to 5.9, you need a workaround. But I'm unsure whether smartpqi_fix_host_qdepth_limit would be the solution. You could simply divide can_queue by nr_hw_queues, as suggested before, or even simpler, set nr_hw_queues = 1. How much performance would that cost you? Distribution kernels would be yet another issue, distros can backport host_tagset and get rid of the issue. Regards Martin