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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=unavailable 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 27F20C48BD3 for ; Wed, 26 Jun 2019 14:22:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id EE4852085A for ; Wed, 26 Jun 2019 14:22:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727139AbfFZOWy (ORCPT ); Wed, 26 Jun 2019 10:22:54 -0400 Received: from smtp.infotech.no ([82.134.31.41]:32887 "EHLO smtp.infotech.no" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725958AbfFZOWx (ORCPT ); Wed, 26 Jun 2019 10:22:53 -0400 X-Greylist: delayed 503 seconds by postgrey-1.27 at vger.kernel.org; Wed, 26 Jun 2019 10:22:52 EDT Received: from localhost (localhost [127.0.0.1]) by smtp.infotech.no (Postfix) with ESMTP id 70355204192; Wed, 26 Jun 2019 16:14:28 +0200 (CEST) X-Virus-Scanned: by amavisd-new-2.6.6 (20110518) (Debian) at infotech.no Received: from smtp.infotech.no ([127.0.0.1]) by localhost (smtp.infotech.no [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id PwazqP0WQn-2; Wed, 26 Jun 2019 16:14:26 +0200 (CEST) Received: from [192.168.48.23] (host-45-58-224-183.dyn.295.ca [45.58.224.183]) by smtp.infotech.no (Postfix) with ESMTPA id CFD38204153; Wed, 26 Jun 2019 16:14:25 +0200 (CEST) Reply-To: dgilbert@interlog.com Subject: Re: [PATCH 0/2] scsi: add support for request batching To: Paolo Bonzini , linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: jejb@linux.ibm.com, martin.petersen@oracle.com, linux-scsi@vger.kernel.org, stefanha@redhat.com References: <20190530112811.3066-1-pbonzini@redhat.com> <746ad64a-4047-1597-a0d4-f14f3529cc19@redhat.com> From: Douglas Gilbert Message-ID: <65e5ad25-a475-989a-ce3d-400a8c90cb61@interlog.com> Date: Wed, 26 Jun 2019 10:14:23 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.1 MIME-Version: 1.0 In-Reply-To: <746ad64a-4047-1597-a0d4-f14f3529cc19@redhat.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-CA Content-Transfer-Encoding: 7bit Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On 2019-06-26 9:51 a.m., Paolo Bonzini wrote: > On 30/05/19 13:28, Paolo Bonzini wrote: >> This allows a list of requests to be issued, with the LLD only writing >> the hardware doorbell when necessary, after the last request was prepared. >> This is more efficient if we have lists of requests to issue, particularly >> on virtualized hardware, where writing the doorbell is more expensive than >> on real hardware. >> >> This applies to any HBA, either singlequeue or multiqueue; the second >> patch implements it for virtio-scsi. >> >> Paolo >> >> Paolo Bonzini (2): >> scsi_host: add support for request batching >> virtio_scsi: implement request batching >> >> drivers/scsi/scsi_lib.c | 37 ++++++++++++++++++++++--- >> drivers/scsi/virtio_scsi.c | 55 +++++++++++++++++++++++++++----------- >> include/scsi/scsi_cmnd.h | 1 + >> include/scsi/scsi_host.h | 16 +++++++++-- >> 4 files changed, 89 insertions(+), 20 deletions(-) >> > > > Ping? Are there any more objections? I have no objections, just a few questions. To implement this is the scsi_debug driver, a per device queue would need to be added, correct? Then a 'commit_rqs' call would be expected at some later point and it would drain that queue and submit each command. Or is the queue draining ongoing in the LLD and 'commit_rqs' means: don't return until that queue is empty? So does that mean in the normal (i.e. non request batching) case there are two calls to the LLD for each submitted command? Or is 'commit_rqs' optional, a sync-ing type command? Doug Gilbert