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=-12.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,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 14C9FC433E1 for ; Mon, 10 Aug 2020 16:51:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DF357207DE for ; Mon, 10 Aug 2020 16:51:22 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=broadcom.com header.i=@broadcom.com header.b="Jrx/GSu1" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726720AbgHJQvV (ORCPT ); Mon, 10 Aug 2020 12:51:21 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48952 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726845AbgHJQvU (ORCPT ); Mon, 10 Aug 2020 12:51:20 -0400 Received: from mail-qv1-xf43.google.com (mail-qv1-xf43.google.com [IPv6:2607:f8b0:4864:20::f43]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 84802C061787 for ; Mon, 10 Aug 2020 09:51:20 -0700 (PDT) Received: by mail-qv1-xf43.google.com with SMTP id s15so4543176qvv.7 for ; Mon, 10 Aug 2020 09:51:20 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=broadcom.com; s=google; h=from:references:in-reply-to:mime-version:thread-index:date :message-id:subject:to:cc; bh=j7Nx7N4OeE4KkW4jW5KoZv1rUhElZ3FsfhltIpm/oPA=; b=Jrx/GSu10mjBSWF2jZr+/m7e/fJA1rnd8TGZPs/A5pZIbFl6YUInjkQ8BOVVmw1aaD JEsc7ZzM8tkQscXbnK8Xls+9V4u0cQElwwTxzPWpc7SOB/Z4NR33t79fwvmuETwXawt6 GTeskoGeAxf82hQPzpISEE4d4rxPChp762jC4= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:references:in-reply-to:mime-version :thread-index:date:message-id:subject:to:cc; bh=j7Nx7N4OeE4KkW4jW5KoZv1rUhElZ3FsfhltIpm/oPA=; b=gmuYPbCF3FyvZwEiACkNBnasGZpIuxsl5GNp/jhBlrh6WvQj7R+lseR46uG4bhKbLp hp7nPU1CoIZKQmnQTX3DMws76BCP7JjusJUbIP9CbmOX6ZcZyjwdytrQ6VKJ8QHkXBft duCCip6LMp5vpBdnKUtOO/4nRiE8Z8x7XUBkX8lgJjeco5sR+RSeX2uCaGlLPRZ3zhYA D7T2QGUebq+dmfGRqkXQn7hGYu1v0Q5TwdDxN487UBAV5/3T1h0dolNNZ9PjJkW5LAat TQgk28n6zkIZ0D3LM3ms/5PDuBdggOCt8Kxtw+Wo0g6nx4u99xxswIwyjD6yUQY+wCEM l9TQ== X-Gm-Message-State: AOAM532/YdgracuEVsChEBNLradxk9cVp+P5zgabjTSteu++LWJa6LPc oLQ4WE1y5+oWXX9z2273pYYuDL4uy74Tcya1bE4lKw== X-Google-Smtp-Source: ABdhPJxWwHQ4+VVD7ZA1DPCQQZe2AzFleL9gJSSX1Hdn4b/7UH0mn0IQslmGaUb9LxTFCqnvFHsxdbqVt0Eb+Dy37aM= X-Received: by 2002:a0c:d981:: with SMTP id y1mr30169563qvj.124.1597078279461; Mon, 10 Aug 2020 09:51:19 -0700 (PDT) From: Kashyap Desai References: <1591810159-240929-1-git-send-email-john.garry@huawei.com> <1591810159-240929-3-git-send-email-john.garry@huawei.com> <20200611025759.GA453671@T590> <6ef76cdf-2fb3-0ce8-5b5a-0d7af0145901@huawei.com> <8ef58912-d480-a7e1-f04c-da9bd85ea0ae@huawei.com> e42da0e714c808c80e9a055f3f065e44@mail.gmail.com In-Reply-To: e42da0e714c808c80e9a055f3f065e44@mail.gmail.com MIME-Version: 1.0 X-Mailer: Microsoft Outlook 15.0 Thread-Index: AQBVjmvxAE7FMYb7GtMRWGcwtMcECgJRJzAeAmYD0J0CUmtFnQMQPP3WAliipVSrhUrmoIBKbxJA Date: Mon, 10 Aug 2020 22:21:16 +0530 Message-ID: <3b80b46173103c62c2f94e25ff517058@mail.gmail.com> Subject: RE: [PATCH RFC v7 02/12] blk-mq: rename blk_mq_update_tag_set_depth() To: Hannes Reinecke , John Garry , Ming Lei Cc: axboe@kernel.dk, jejb@linux.ibm.com, martin.petersen@oracle.com, don.brace@microsemi.com, Sumit Saxena , bvanassche@acm.org, hare@suse.com, hch@lst.de, Shivasharan Srikanteshwara , linux-block@vger.kernel.org, linux-scsi@vger.kernel.org, esc.storagedev@microsemi.com, chenxiang66@hisilicon.com Content-Type: text/plain; charset="UTF-8" Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org > > Kashyap, I've also attached an updated patch for the elevator_count > > patch; if you agree John can include it in the next version. > > Hannes - Patch looks good. Header does not include problem statement. > How about adding below in header ? > > High CPU utilization on "native_queued_spin_lock_slowpath" due to lock > contention is possible in mq-deadline and bfq io scheduler when > nr_hw_queues is more than one. > It is because kblockd work queue can submit IO from all online CPUs > (through > blk_mq_run_hw_queues) even though only one hctx has pending commands. > Elevator callback "has_work" for mq-deadline and bfq scheduler consider > pending work if there are any IOs on request queue and it does not account > hctx context. Hannes/John - We need one more correction for below patch - https://github.com/hisilicon/kernel-dev/commit/ff631eb80aa0449eaeb78a282fd7eff2a9e42f77 I noticed - that elevator_queued count goes negative mainly because there are some case where IO was submitted from dispatch queue(not scheduler queue) and request still has "RQF_ELVPRIV" flag set. In such cases " dd_finish_request" is called without " dd_insert_request". I think it is better to decrement counter once it is taken out from dispatched queue. (Ming proposed to use dispatch path for decrementing counter, but I somehow did not accounted assuming RQF_ELVPRIV will be set only if IO is submitted from scheduler queue.) Below is additional change. Can you merge this ? diff --git a/block/mq-deadline.c b/block/mq-deadline.c index 9d75374..bc413dd 100644 --- a/block/mq-deadline.c +++ b/block/mq-deadline.c @@ -385,6 +385,8 @@ static struct request *dd_dispatch_request(struct blk_mq_hw_ctx *hctx) spin_lock(&dd->lock); rq = __dd_dispatch_request(dd); + if (rq) + atomic_dec(&rq->mq_hctx->elevator_queued); spin_unlock(&dd->lock); return rq; @@ -574,7 +576,6 @@ static void dd_finish_request(struct request *rq) blk_mq_sched_mark_restart_hctx(rq->mq_hctx); spin_unlock_irqrestore(&dd->zone_lock, flags); } - atomic_dec(&rq->mq_hctx->elevator_queued); } static bool dd_has_work(struct blk_mq_hw_ctx *hctx) -- 2.9.5 Kashyap