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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,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 9DC98C433E0 for ; Fri, 12 Jun 2020 06:06:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7E01B20838 for ; Fri, 12 Jun 2020 06:06:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726448AbgFLGGH (ORCPT ); Fri, 12 Jun 2020 02:06:07 -0400 Received: from mx2.suse.de ([195.135.220.15]:44954 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726391AbgFLGGH (ORCPT ); Fri, 12 Jun 2020 02:06:07 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id 67F77AD5E; Fri, 12 Jun 2020 06:06:07 +0000 (UTC) Subject: Re: [PATCH RFC v7 07/12] blk-mq: Add support in hctx_tags_bitmap_show() for a shared sbitmap To: John Garry , axboe@kernel.dk, jejb@linux.ibm.com, martin.petersen@oracle.com, don.brace@microsemi.com, kashyap.desai@broadcom.com, sumit.saxena@broadcom.com, ming.lei@redhat.com, bvanassche@acm.org, hare@suse.com, hch@lst.de, shivasharan.srikanteshwara@broadcom.com Cc: linux-block@vger.kernel.org, linux-scsi@vger.kernel.org, esc.storagedev@microsemi.com, chenxiang66@hisilicon.com, megaraidlinux.pdl@broadcom.com References: <1591810159-240929-1-git-send-email-john.garry@huawei.com> <1591810159-240929-8-git-send-email-john.garry@huawei.com> <9f4741c5-d117-d764-cf3a-a57192a788c3@suse.de> From: Hannes Reinecke Message-ID: <7ed6ccf1-6ad9-1df7-f55d-4ed6cac1e08d@suse.de> Date: Fri, 12 Jun 2020 08:06:00 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.8.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-scsi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-scsi@vger.kernel.org On 6/11/20 4:33 PM, John Garry wrote: >>> +static int hctx_tags_shared_sbitmap_bitmap_show(void *data, struct >>> seq_file *m) >>> +{ >>> +    struct blk_mq_hw_ctx *hctx = data; >>> +    struct request_queue *q = hctx->queue; >>> +    struct blk_mq_tag_set *set = q->tag_set; >>> +    struct sbitmap shared_sb, *sb; >>> +    int res; >>> + >>> +    if (!set) >>> +        return 0; >>> + >>> +    /* >>> +     * We could use the allocated sbitmap for that hctx here, but >>> +     * that would mean that we would need to clean it prior to use. >>> +     */ > > * > >>> +    res = sbitmap_init_node(&shared_sb, >>> +                set->__bitmap_tags.sb.depth, >>> +                set->__bitmap_tags.sb.shift, >>> +                GFP_KERNEL, NUMA_NO_NODE); >>> +    if (res) >>> +        return res; >>> +    sb = &shared_sb; >>> + >>> +    res = mutex_lock_interruptible(&q->sysfs_lock); >>> +    if (res) >>> +        goto out; >>> +    if (hctx->tags) { >>> +        hctx_filter_sb(sb, hctx); >>> +        sbitmap_bitmap_show(sb, m); >>> +    } >>> + >>> +    mutex_unlock(&q->sysfs_lock); >>> + >>> +out: >>> +    sbitmap_free(&shared_sb); >>> +    return res; >>> +} >>> + >>>   static int hctx_tags_bitmap_show(void *data, struct seq_file *m) >>>   { >>>       struct blk_mq_hw_ctx *hctx = data; >>> @@ -823,6 +884,7 @@ static const struct blk_mq_debugfs_attr >>> blk_mq_debugfs_hctx_shared_sbitmap_attrs >>>       {"busy", 0400, hctx_busy_show}, >>>       {"ctx_map", 0400, hctx_ctx_map_show}, >>>       {"tags", 0400, hctx_tags_show}, >>> +    {"tags_bitmap", 0400, hctx_tags_shared_sbitmap_bitmap_show}, >>>       {"sched_tags", 0400, hctx_sched_tags_show}, >>>       {"sched_tags_bitmap", 0400, hctx_sched_tags_bitmap_show}, >>>       {"io_poll", 0600, hctx_io_poll_show, hctx_io_poll_write}, >>> >> Ah, right. Here it is. >> >> But I don't get it; why do we have to allocate a temporary bitmap and >> can't walk the existing shared sbitmap? > > For the bitmap dump - sbitmap_bitmap_show() - it is passed a struct > sbitmap *. So we have to filter into a temp per-hctx struct sbitmap. We > could change sbitmap_bitmap_show() to accept a filter iterator - which I > think you're getting at - but I am not sure it's worth the change. Or > else use the allocated sbitmap for the hctx, as above*, but I may be > remove that (see 4/12 response). > Yes, I do think I would prefer updating sbitmap_bitmap_show() to accept a filter. Especially as Ming Lei has now updated the tag iterators to accept a filter, too, so it should be an easy change. Cheers, Hannes -- Dr. Hannes Reinecke Teamlead Storage & Networking hare@suse.de +49 911 74053 688 SUSE Software Solutions GmbH, Maxfeldstr. 5, 90409 Nürnberg HRB 36809 (AG Nürnberg), Geschäftsführer: Felix Imendörffer