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 F38A2C433DF for ; Mon, 24 Aug 2020 16:41:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B03BC20738 for ; Mon, 24 Aug 2020 16:41:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1598287275; bh=p8BE7X+nZ6st4U/GVQwBf0Sc/g1a6v51AjLXWy+aJXQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=lx9KDHF9JYYEN0QorXmUykV2cgH3r0nuV1Ao4TrDddPUUho0QcjwbTb2ElipbpKB9 2mT7la1n3LMYKLI1fgrqz5Bl7rAcGkZcn8z9sURuHiKrGY7PI3SbdBp4oC97nb3V8w CIim/whOYpHNj9FrV9JFAcG28TDZJ6igvZ8SSiF4= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726691AbgHXQlJ (ORCPT ); Mon, 24 Aug 2020 12:41:09 -0400 Received: from mail.kernel.org ([198.145.29.99]:47672 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728601AbgHXQjj (ORCPT ); Mon, 24 Aug 2020 12:39:39 -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 4F8DC22D3E; Mon, 24 Aug 2020 16:39:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1598287177; bh=p8BE7X+nZ6st4U/GVQwBf0Sc/g1a6v51AjLXWy+aJXQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=XuXpSbZKKMQeJJEAmX6wqSu6fH12guoA5eCdI0MWB0h1vtu/sgP42E0JMrjOy7z1Z XSLefBtf8F6oZKSwP/wdjDaKvInEPTl4AeGwAur7z0TUxHIvD8ILIFE9P9QC1hhgv0 CIMK9NTV77WG685foqmnvNkNga58a7rbzJ8iipn8= 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 4.9 4/8] s390/cio: add cond_resched() in the slow_eval_known_fn() loop Date: Mon, 24 Aug 2020 12:39:27 -0400 Message-Id: <20200824163931.607291-4-sashal@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200824163931.607291-1-sashal@kernel.org> References: <20200824163931.607291-1-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 39a2b0cde9e42..d81fdcd6a1fe0 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