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 CCE0AC433E1 for ; Mon, 24 Aug 2020 17:03:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A89E0206F0 for ; Mon, 24 Aug 2020 17:03:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1598288631; bh=TJXeZSGzwfNiVC7VyxV4h8RVxP7uqTTnzNYyvYWstFk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=Xzxqb7RJFqvdQ142cuiRwjYVJSRiZbDNZBYibX5s9AK+NemRwq+jnFqnoOaHdhSn9 4xr700SwKG/1ZG2YkLz/dKIGE+myoohUmLwxrjcptZZEQDNV38jaOz/IRfUcS3Jxg9 7X/hooEYaypYlRDE1HC3xHBBwFJOViX0MQ/vKoUM= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727863AbgHXRDs (ORCPT ); Mon, 24 Aug 2020 13:03:48 -0400 Received: from mail.kernel.org ([198.145.29.99]:40220 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728476AbgHXQih (ORCPT ); Mon, 24 Aug 2020 12:38:37 -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 3729A22D3E; Mon, 24 Aug 2020 16:38:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1598287100; bh=TJXeZSGzwfNiVC7VyxV4h8RVxP7uqTTnzNYyvYWstFk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=zt9yKCMABXKOp16BIU7FB7fGKrhHBcOP0yeciPQk4EVpWuzWc1n8Yy3t24IW8QDXi uPhHV9MDOVoqAS7Co/QUwP8ZG5LqHJJQJgFxkOX3QillafIxzRUL/1TFfooFwlAyvO dBONpQpeKosGYXD/QE6R4UA5WTiVdWVwRH7xDGnQ= 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 5.4 21/38] s390/cio: add cond_resched() in the slow_eval_known_fn() loop Date: Mon, 24 Aug 2020 12:37:33 -0400 Message-Id: <20200824163751.606577-21-sashal@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200824163751.606577-1-sashal@kernel.org> References: <20200824163751.606577-1-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 831850435c23b..5734a78dbb8e6 100644 --- a/drivers/s390/cio/css.c +++ b/drivers/s390/cio/css.c @@ -677,6 +677,11 @@ 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