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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 537A5EE4993 for ; Sun, 20 Aug 2023 16:26:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230499AbjHTQ0Y (ORCPT ); Sun, 20 Aug 2023 12:26:24 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43114 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229944AbjHTQ0W (ORCPT ); Sun, 20 Aug 2023 12:26:22 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AF31211D for ; Sun, 20 Aug 2023 09:24:47 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1692548687; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=LTIIx7UvbdXxFhLIfELCeFcfxNRehzpT464zSPyQ1Nc=; b=dsiNBXUBOjKDeCbelycL8TBv7gZX8xSqp57aF+AvTiX3rIQCu6qt5jeBSGTcRGk2wWlmeJ /xBcfo0diUL/pz9CmGBDyPvxRhGdhZDoUBnexdX/CrQZZfWaZ4ieBfk9WInoITTFZ0uvv1 FhhX4h6Filr/NMd1du2ojV57NaTU0KA= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-569-KieFKDpHPWS2QniEUA84iw-1; Sun, 20 Aug 2023 12:24:41 -0400 X-MC-Unique: KieFKDpHPWS2QniEUA84iw-1 Received: from smtp.corp.redhat.com (int-mx10.intmail.prod.int.rdu2.redhat.com [10.11.54.10]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id A8BFE833948; Sun, 20 Aug 2023 16:24:40 +0000 (UTC) Received: from [10.22.16.56] (unknown [10.22.16.56]) by smtp.corp.redhat.com (Postfix) with ESMTP id E8C7D492C13; Sun, 20 Aug 2023 16:24:33 +0000 (UTC) Message-ID: <883a5a4f-b34e-689c-2fbd-7bf03db532eb@redhat.com> Date: Sun, 20 Aug 2023 12:24:33 -0400 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.7.1 Subject: Re: [PATCH 0/6] Backport rework of deadline bandwidth restoration for 5.10.y Content-Language: en-US To: Qais Yousef , stable@vger.kernel.org Cc: Juri Lelli , Tejun Heo , Dietmar Eggemann , Peter Zijlstra , Vincent Guittot , Ingo Molnar , Hao Luo , John Stultz , cgroups@vger.kernel.org, linux-kernel@vger.kernel.org References: <20230820152144.517461-1-qyousef@layalina.io> From: Waiman Long In-Reply-To: <20230820152144.517461-1-qyousef@layalina.io> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 3.1 on 10.11.54.10 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 8/20/23 11:21, Qais Yousef wrote: > This is a backport of the series that fixes the way deadline bandwidth > restoration is done which is causing noticeable delay on resume path. It also > converts the cpuset lock back into a mutex which some users on Android too. > I lack the details but AFAIU the read/write semaphore was slower on high > contention. Note that it was a percpu rwsem before this patch series. It was not a regular rwsem. Percpu rwsem isn't designed to handle high write lock contention. A regular rwsem should be similar to mutex in performance when handling high write lock contention. Cheers, Longman