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=-5.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 6A349C83012 for ; Wed, 2 Dec 2020 12:04:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1374C206A4 for ; Wed, 2 Dec 2020 12:04:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729485AbgLBMEA (ORCPT ); Wed, 2 Dec 2020 07:04:00 -0500 Received: from mx2.suse.de ([195.135.220.15]:45838 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727100AbgLBMEA (ORCPT ); Wed, 2 Dec 2020 07:04:00 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id CF2A5AB63; Wed, 2 Dec 2020 12:03:18 +0000 (UTC) Subject: Re: [PATCH 00/13] ibmvfc: initial MQ development To: Tyrel Datwyler , james.bottomley@hansenpartnership.com Cc: martin.petersen@oracle.com, linux-scsi@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, brking@linux.ibm.com References: <20201126014824.123831-1-tyreld@linux.ibm.com> From: Hannes Reinecke Message-ID: <90e9a8ac-d2b9-bb64-7c7d-607adaea0f26@suse.de> Date: Wed, 2 Dec 2020 13:03:18 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.4.0 MIME-Version: 1.0 In-Reply-To: <20201126014824.123831-1-tyreld@linux.ibm.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/26/20 2:48 AM, Tyrel Datwyler wrote: > Recent updates in pHyp Firmware and VIOS releases provide new infrastructure > towards enabling Subordinate Command Response Queues (Sub-CRQs) such that each > Sub-CRQ is a channel backed by an actual hardware queue in the FC stack on the > partner VIOS. Sub-CRQs are registered with the firmware via hypercalls and then > negotiated with the VIOS via new Management Datagrams (MADs) for channel setup. > > This initial implementation adds the necessary Sub-CRQ framework and implements > the new MADs for negotiating and assigning a set of Sub-CRQs to associated VIOS > HW backed channels. The event pool and locking still leverages the legacy single > queue implementation, and as such lock contention is problematic when increasing > the number of queues. However, this initial work demonstrates a 1.2x factor > increase in IOPs when configured with two HW queues despite lock contention. > Why do you still hold the hold lock during submission? An initial check on the submission code path didn't reveal anything obvious, so it _should_ be possible to drop the host lock there. Or at least move it into the submission function itself to avoid lock contention. Hmm? Cheers, Hannes -- Dr. Hannes Reinecke Kernel Storage Architect hare@suse.de +49 911 74053 688 SUSE Software Solutions GmbH, Maxfeldstr. 5, 90409 Nürnberg HRB 36809 (AG Nürnberg), Geschäftsführer: Felix Imendörffer