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 7B69DC433DF for ; Mon, 24 Aug 2020 16:42:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4D65420866 for ; Mon, 24 Aug 2020 16:42:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1598287338; bh=BWK2hS0GdXLTqvn3LCDebg7pXZphF7c3VLKfxq34sFk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=13+YaV6RNvGp80Q7H1QtiFKSNX+agzbqoE/pG/67b6W+hxB4VoOeswSzxLsuZAkm7 zQ2cw8yiGK8aHtZ4w2n+jAe5ilN3uogH2I1vCHZrIHjUORNAawDttxBSID6Tw2fGL7 qltlUt4Xk+8Cuu8hBbPhQP9tqkvQWNPv742SueOY= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728153AbgHXQmN (ORCPT ); Mon, 24 Aug 2020 12:42:13 -0400 Received: from mail.kernel.org ([198.145.29.99]:47964 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728623AbgHXQjs (ORCPT ); Mon, 24 Aug 2020 12:39:48 -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 EBB8320838; Mon, 24 Aug 2020 16:39:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1598287187; bh=BWK2hS0GdXLTqvn3LCDebg7pXZphF7c3VLKfxq34sFk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Hm/qvMS8UTUZRx3+hdE+hFeKSSLJlIc0yxiT/3IN5RluUdxcgJqiL98wJUMWfi6b8 WdITJuV2q5gj2pj+C4XDf1l/Q2AOXJglow4qG4k/oAsS72wvBa9bdiG21txy5wEBFk vn0KnusnMjRPCS0VIw9xde6Rq8Io8odwEKTaqTO0= 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 4.4 3/6] s390/cio: add cond_resched() in the slow_eval_known_fn() loop Date: Mon, 24 Aug 2020 12:39:40 -0400 Message-Id: <20200824163943.607406-3-sashal@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200824163943.607406-1-sashal@kernel.org> References: <20200824163943.607406-1-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 8ecc956ecb59c..370a3a2c6de73 100644 --- a/drivers/s390/cio/css.c +++ b/drivers/s390/cio/css.c @@ -529,6 +529,11 @@ 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