From patchwork Mon Apr 20 16:24:51 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Doug Anderson X-Patchwork-Id: 11499337 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 0B77C13B2 for ; Mon, 20 Apr 2020 16:25:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E8A0520B1F for ; Mon, 20 Apr 2020 16:25:45 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="oLc3AJ2z" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728770AbgDTQZ1 (ORCPT ); Mon, 20 Apr 2020 12:25:27 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39440 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1728519AbgDTQZ0 (ORCPT ); Mon, 20 Apr 2020 12:25:26 -0400 Received: from mail-pl1-x644.google.com (mail-pl1-x644.google.com [IPv6:2607:f8b0:4864:20::644]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 97A64C061A0F for ; Mon, 20 Apr 2020 09:25:24 -0700 (PDT) Received: by mail-pl1-x644.google.com with SMTP id d24so4129368pll.8 for ; Mon, 20 Apr 2020 09:25:24 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=5/HuxgmmHlqReW6h8RDiDPaUU+foeFL9gMHI9mR80zQ=; b=oLc3AJ2zDSkJUS41so2hjSzJWNKd+wQTQRY105W2+x1kDo67B9HBOmeWMj71MixgMx Or9Sk5sj3rNm2US+gKQTp3Pa4AgxhFV4SqxT7+A6HxzfaKFMFsWyQbXAeSfmPoABqpNl Co26ffksskFcKs3YvP8b3uw/2SKxJVLuMvcn8= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=5/HuxgmmHlqReW6h8RDiDPaUU+foeFL9gMHI9mR80zQ=; b=Nq7jC9v/CHrvQVwO0dX0EvFATNpWEupSqcWAjHD7aLFD0mF6joPjqljeW2zYYpEeaO 8htjfTmlAQc7Hro3b+3r0UEmZQRgQhQ6r702YQgMNd1TuNH5SFgGQwBLSIdmdRdcSni+ wbfs01q06xGzktlMoxT11TJMj71rDGg8O51tGWQIN19fw9xpq2o6x0DOgkcm5fT4cbLh ZurXrkFIdXK054pFlSiA+K9bebbRilWrVaCZAmfTQTWjKRyPOse8ELOMz4sc6IMtfDnu AdqduXE7FT58ky5MEqWUbFXNFzjyugXBFk1a+HlrHGNfyuDh3NFtPJEEcNoKH4V+2w2k rsmQ== X-Gm-Message-State: AGi0PuY281LMFpjZqmVTykZ43qWg8MddbbtYcwsPY95IpEUnNDU1r9Zl v2sHQiz2Pxp0CmzKRteLkSKcbw== X-Google-Smtp-Source: APiQypKpCrNnEeTYcINBy79o3eKcejCinyX6OW/b2TJcQxL+18Xe1Dv9nBf3MYUu730zR6e0r+X2hA== X-Received: by 2002:a17:90a:710a:: with SMTP id h10mr213647pjk.152.1587399924208; Mon, 20 Apr 2020 09:25:24 -0700 (PDT) Received: from tictac2.mtv.corp.google.com ([2620:15c:202:1:24fa:e766:52c9:e3b2]) by smtp.gmail.com with ESMTPSA id p64sm93150pjp.7.2020.04.20.09.25.23 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 20 Apr 2020 09:25:23 -0700 (PDT) From: Douglas Anderson To: axboe@kernel.dk, jejb@linux.ibm.com, martin.petersen@oracle.com Cc: linux-scsi@vger.kernel.org, Gwendal Grignou , sqazi@google.com, groeck@chromium.org, Ming Lei , linux-block@vger.kernel.org, paolo.valente@linaro.org, Douglas Anderson , linux-kernel@vger.kernel.org Subject: [PATCH v5 1/4] blk-mq: In blk_mq_dispatch_rq_list() "no budget" is a reason to kick Date: Mon, 20 Apr 2020 09:24:51 -0700 Message-Id: <20200420092357.v5.1.I1f95c459e51962b8d2c83e869913b6befda2255c@changeid> X-Mailer: git-send-email 2.26.1.301.g55bc3eb7cb9-goog In-Reply-To: <20200420162454.48679-1-dianders@chromium.org> References: <20200420162454.48679-1-dianders@chromium.org> MIME-Version: 1.0 Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org In blk_mq_dispatch_rq_list(), if blk_mq_sched_needs_restart() returns true and the driver returns BLK_STS_RESOURCE then we'll kick the queue. However, there's another case where we might need to kick it. If we were unable to get budget we can be in much the same state as when the driver returns BLK_STS_RESOURCE, so we should treat it the same. It should be noted that even if we add a whole bunch of extra kicking to the queue in other patches this patch is still important. Specifically any kicking that happened before we re-spliced leftover requests into 'hctx->dispatch' wouldn't have found any work, so we really need to make sure we kick ourselves after we've done the splicing. Signed-off-by: Douglas Anderson Reviewed-by: Ming Lei --- Changes in v5: - Rebase atop commit 5fe56de799ad ("...Put driver tag...when no budget") Changes in v4: None Changes in v3: - Note why blk_mq_dispatch_rq_list() change is needed. Changes in v2: None block/blk-mq.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/block/blk-mq.c b/block/blk-mq.c index a7785df2c944..1c4bedf500c5 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -1206,6 +1206,7 @@ bool blk_mq_dispatch_rq_list(struct request_queue *q, struct list_head *list, bool no_tag = false; int errors, queued; blk_status_t ret = BLK_STS_OK; + bool no_budget_avail = false; if (list_empty(list)) return false; @@ -1224,6 +1225,7 @@ bool blk_mq_dispatch_rq_list(struct request_queue *q, struct list_head *list, hctx = rq->mq_hctx; if (!got_budget && !blk_mq_get_dispatch_budget(hctx)) { blk_mq_put_driver_tag(rq); + no_budget_avail = true; break; } @@ -1320,13 +1322,15 @@ bool blk_mq_dispatch_rq_list(struct request_queue *q, struct list_head *list, * * If driver returns BLK_STS_RESOURCE and SCHED_RESTART * bit is set, run queue after a delay to avoid IO stalls - * that could otherwise occur if the queue is idle. + * that could otherwise occur if the queue is idle. We'll do + * similar if we couldn't get budget and SCHED_RESTART is set. */ needs_restart = blk_mq_sched_needs_restart(hctx); if (!needs_restart || (no_tag && list_empty_careful(&hctx->dispatch_wait.entry))) blk_mq_run_hw_queue(hctx, true); - else if (needs_restart && (ret == BLK_STS_RESOURCE)) + else if (needs_restart && (ret == BLK_STS_RESOURCE || + no_budget_avail)) blk_mq_delay_run_hw_queue(hctx, BLK_MQ_RESOURCE_DELAY); blk_mq_update_dispatch_busy(hctx, true);