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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 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 CC74BC54FCC for ; Tue, 21 Apr 2020 15:17:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AF37B2068F for ; Tue, 21 Apr 2020 15:17:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725987AbgDUPR3 (ORCPT ); Tue, 21 Apr 2020 11:17:29 -0400 Received: from lhrrgout.huawei.com ([185.176.76.210]:2076 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725870AbgDUPR3 (ORCPT ); Tue, 21 Apr 2020 11:17:29 -0400 Received: from lhreml724-chm.china.huawei.com (unknown [172.18.7.106]) by Forcepoint Email with ESMTP id E1CC71CC61834FD3D317; Tue, 21 Apr 2020 16:17:26 +0100 (IST) Received: from [127.0.0.1] (10.210.168.25) by lhreml724-chm.china.huawei.com (10.201.108.75) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.1913.5; Tue, 21 Apr 2020 16:17:26 +0100 Subject: Re: [PATCH] scsi: put hot fields of scsi_host_template into one cacheline To: Ming Lei , James Bottomley , , "Martin K . Petersen" CC: Bart Van Assche , Christoph Hellwig References: <20200421124952.297448-1-ming.lei@redhat.com> From: John Garry Message-ID: <367d58f7-722d-16db-3e90-50dc9fd4e078@huawei.com> Date: Tue, 21 Apr 2020 16:16:52 +0100 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.1.2 MIME-Version: 1.0 In-Reply-To: <20200421124952.297448-1-ming.lei@redhat.com> Content-Type: text/plain; charset="utf-8"; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.210.168.25] X-ClientProxiedBy: lhreml719-chm.china.huawei.com (10.201.108.70) To lhreml724-chm.china.huawei.com (10.201.108.75) X-CFilter-Loop: Reflected Sender: linux-scsi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-scsi@vger.kernel.org On 21/04/2020 13:49, Ming Lei wrote: > The following three fields of scsi_host_template are referenced in > scsi IO submission path, so put them together into one cacheline: > > - cmd_size > - queuecommand > - commit_rqs > > Cc: Bart Van Assche > Cc: Christoph Hellwig > Cc: John Garry > Signed-off-by: Ming Lei > --- > include/scsi/scsi_host.h | 67 +++++++++++++++++++++------------------- > 1 file changed, 35 insertions(+), 32 deletions(-) > > diff --git a/include/scsi/scsi_host.h b/include/scsi/scsi_host.h > index 822e8cda8d9b..959dc5160f72 100644 > --- a/include/scsi/scsi_host.h > +++ b/include/scsi/scsi_host.h > @@ -33,37 +33,12 @@ struct scsi_host_template { > struct module *module; > const char *name; > > - /* > - * The info function will return whatever useful information the > - * developer sees fit. If not provided, then the name field will > - * be used instead. > - * > - * Status: OPTIONAL > - */ > - const char *(* info)(struct Scsi_Host *); > + /* Put hot fields together in same cacheline */ > > /* > - * Ioctl interface > - * > - * Status: OPTIONAL > - */ > - int (*ioctl)(struct scsi_device *dev, unsigned int cmd, > - void __user *arg); > - > - > -#ifdef CONFIG_COMPAT > - /* > - * Compat handler. Handle 32bit ABI. > - * When unknown ioctl is passed return -ENOIOCTLCMD. > - * > - * Status: OPTIONAL > + * Additional per-command data allocated for the driver. > */ > - int (*compat_ioctl)(struct scsi_device *dev, unsigned int cmd, > - void __user *arg); > -#endif > - > - int (*init_cmd_priv)(struct Scsi_Host *shost, struct scsi_cmnd *cmd); > - int (*exit_cmd_priv)(struct Scsi_Host *shost, struct scsi_cmnd *cmd); Should new member .init_cmd_priv be included also in the "hot" group? Even if NULL generally, we still have to load that from memory to know it (is NULL) in scsi_mq_init_request() and scsi_init_command() [which are fastpath, right?] Cheers, John > + unsigned int cmd_size; > > /* > * The queuecommand function is used to queue up a scsi > @@ -111,6 +86,38 @@ struct scsi_host_template { > */ > void (*commit_rqs)(struct Scsi_Host *, u16); > > + /* > + * The info function will return whatever useful information the > + * developer sees fit. If not provided, then the name field will > + * be used instead. > + * > + * Status: OPTIONAL > + */ > + const char *(* info)(struct Scsi_Host *); > + > + /* > + * Ioctl interface > + * > + * Status: OPTIONAL > + */ > + int (*ioctl)(struct scsi_device *dev, unsigned int cmd, > + void __user *arg); > + > + > +#ifdef CONFIG_COMPAT > + /* > + * Compat handler. Handle 32bit ABI. > + * When unknown ioctl is passed return -ENOIOCTLCMD. > + * > + * Status: OPTIONAL > + */ > + int (*compat_ioctl)(struct scsi_device *dev, unsigned int cmd, > + void __user *arg); > +#endif > + > + int (*init_cmd_priv)(struct Scsi_Host *shost, struct scsi_cmnd *cmd); > + int (*exit_cmd_priv)(struct Scsi_Host *shost, struct scsi_cmnd *cmd); > + > /* > * This is an error handling strategy routine. You don't need to > * define one of these if you don't want to - there is a default > @@ -468,10 +475,6 @@ struct scsi_host_template { > */ > u64 vendor_id; > > - /* > - * Additional per-command data allocated for the driver. > - */ > - unsigned int cmd_size; > struct scsi_host_cmd_pool *cmd_pool; > > /* Delay for runtime autosuspend */ >