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=ham 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 405FDC433DF for ; Mon, 24 Aug 2020 16:58:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 089212067C for ; Mon, 24 Aug 2020 16:58:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1598288282; bh=9WsD+M7msmhvOrmHNhbANDUr/qQT8t+aOQRv8aa9ybg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=pMxYdPJ/sUJidmPrV8qP6gP3rkRrdYqHjDSpHWWnDAcaxCNxYsgcoLF7vc4YqMTXC cF7YHMQoSt3jo2LPtP5ReLpU/NMXef0Q1G3AK15jlVy28xmpq+ZK7Vu+L2S+TpnIqe bQfbeBM3lsU39CwxdlKpZSYdh+QYVd/UyCQAA/3o= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726691AbgHXQ57 (ORCPT ); Mon, 24 Aug 2020 12:57:59 -0400 Received: from mail.kernel.org ([198.145.29.99]:46350 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728532AbgHXQi7 (ORCPT ); Mon, 24 Aug 2020 12:38:59 -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 72BFD22D08; Mon, 24 Aug 2020 16:38:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1598287139; bh=9WsD+M7msmhvOrmHNhbANDUr/qQT8t+aOQRv8aa9ybg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=a/6Dc4nasg/Aqo22rLH6mPOIhbbkoR6UqDARiUChV30jY6ji3kaKPIK29EXdyljsF bY5JZiDcLHZDNTbVGEQA1ShEQPf26T7EJChlRbz+EzayKnLQq8vrkt+KvoFzJvM58u e6JEtwDnmqD4QUnhRmpcwmU88W7tc93FVPFyjDRY= 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 4.19 10/21] s390/cio: add cond_resched() in the slow_eval_known_fn() loop Date: Mon, 24 Aug 2020 12:38:34 -0400 Message-Id: <20200824163845.606933-10-sashal@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200824163845.606933-1-sashal@kernel.org> References: <20200824163845.606933-1-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 df09ed53ab459..825a8f2703b4f 100644 --- a/drivers/s390/cio/css.c +++ b/drivers/s390/cio/css.c @@ -615,6 +615,11 @@ 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