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=-14.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT 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 3EF28C433DF for ; Mon, 24 Aug 2020 16:46:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 108502067C for ; Mon, 24 Aug 2020 16:46:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1598287564; bh=4TG4KMIY0v5Q13GLnA/64q9bgsmokJekESKQfdHsjfM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=zgMdwcNS6HxEmtPBJDXwU4mU4CEotxPFlqDjlcoog6EYbmgfVyVedEAkqKxpEGGV6 nM3HmG1QgvdiEmnw27p8DLuhc1qMS1WPi4WX4bTHvqJoqT10QpfqGYzue9aYfBJgLQ OD9dMp++NGFpYHv51zvuzb02PbfLal6Uhwjo3JZ8= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728836AbgHXQqA (ORCPT ); Mon, 24 Aug 2020 12:46:00 -0400 Received: from mail.kernel.org ([198.145.29.99]:47194 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728586AbgHXQjX (ORCPT ); Mon, 24 Aug 2020 12:39:23 -0400 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 9A33D22CB1; Mon, 24 Aug 2020 16:39:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1598287163; bh=4TG4KMIY0v5Q13GLnA/64q9bgsmokJekESKQfdHsjfM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ooHO/LAYaVVxBXlO4WkbAZ74n6SUBGoWdlBb8lf624HN3fx1zge4ugzww+plaDIht iAqK7JP55N6XGT1OvzPjr2VATvfvf42qYBfOc6EAIVujCw474LFsOkdKJp2YsqbULN 7979X0Satwtymic4d19z63+YvOvnbHqsxHdpdV6E= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Vineeth Vijayan , Peter Oberparleiter , Heiko Carstens , Sasha Levin , linux-s390@vger.kernel.org Subject: [PATCH AUTOSEL 4.14 06/11] s390/cio: add cond_resched() in the slow_eval_known_fn() loop Date: Mon, 24 Aug 2020 12:39:09 -0400 Message-Id: <20200824163914.607152-6-sashal@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200824163914.607152-1-sashal@kernel.org> References: <20200824163914.607152-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Vineeth Vijayan [ Upstream commit 0b8eb2ee9da1e8c9b8082f404f3948aa82a057b2 ] The scanning through subchannels during the time of an event could take significant amount of time in case of platforms with lots of known subchannels. This might result in higher scheduling latencies for other tasks especially on systems with a single CPU. Add cond_resched() call, as the loop in slow_eval_known_fn() can be executed for a longer duration. Reviewed-by: Peter Oberparleiter Signed-off-by: Vineeth Vijayan Signed-off-by: Heiko Carstens Signed-off-by: Sasha Levin --- drivers/s390/cio/css.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/drivers/s390/cio/css.c b/drivers/s390/cio/css.c index dadff1838fec1..e2026d54dd375 100644 --- a/drivers/s390/cio/css.c +++ b/drivers/s390/cio/css.c @@ -581,6 +581,11 @@ static int slow_eval_known_fn(struct subchannel *sch, void *data) rc = css_evaluate_known_subchannel(sch, 1); if (rc == -EAGAIN) css_schedule_eval(sch->schid); + /* + * The loop might take long time for platforms with lots of + * known devices. Allow scheduling here. + */ + cond_resched(); } return 0; } -- 2.25.1