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=-2.4 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 2A353CA9EC5 for ; Wed, 30 Oct 2019 15:57:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E930C2173E for ; Wed, 30 Oct 2019 15:57:44 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="I7SsVN9G" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729147AbfJ3P5o (ORCPT ); Wed, 30 Oct 2019 11:57:44 -0400 Received: from us-smtp-2.mimecast.com ([205.139.110.61]:44064 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1729108AbfJ3P5i (ORCPT ); Wed, 30 Oct 2019 11:57:38 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1572451057; 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=oxmCKrD+1huL0UnafF7o9Ji5BC44afhsjiSZaqIxSAE=; b=I7SsVN9Gl7zM5T0qSgOQHhhljbktufEt814fDDed815BzIq6XFqKvxlnP5npYgwa1yd5aq OUHBcoZKdVcASaKTt36N/+0Ndr4oyxTS4VFW9+tqU2G81QYGlKOJnkyuxUKFHmffEaYelY KMy/8bSV0KIfbdUPv2TPkKlc1AP1roM= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-204-37-W3smINPiQ0aJcgrG5ag-1; Wed, 30 Oct 2019 11:57:36 -0400 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 92F3A800EB3; Wed, 30 Oct 2019 15:57:34 +0000 (UTC) Received: from dhcp-27-174.brq.redhat.com (unknown [10.40.206.16]) by smtp.corp.redhat.com (Postfix) with SMTP id 52D85808B; Wed, 30 Oct 2019 15:57:21 +0000 (UTC) Received: by dhcp-27-174.brq.redhat.com (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Wed, 30 Oct 2019 16:57:34 +0100 (CET) Date: Wed, 30 Oct 2019 16:57:20 +0100 From: Oleg Nesterov To: Peter Zijlstra Cc: Will Deacon , Ingo Molnar , Thomas Gleixner , linux-kernel@vger.kernel.org, bigeasy@linutronix.de, juri.lelli@redhat.com, williams@redhat.com, bristot@redhat.com, longman@redhat.com, dave@stgolabs.net, jack@suse.com Subject: Re: [PATCH] locking/percpu_rwsem: Rewrite to not use rwsem Message-ID: <20191030155720.GA20713@redhat.com> References: <20190805140241.GI2332@hirez.programming.kicks-ass.net> <20190807144305.v55fohssujsqtegb@willie-the-truck> <20191029190624.GB3079@worktop.programming.kicks-ass.net> MIME-Version: 1.0 In-Reply-To: <20191029190624.GB3079@worktop.programming.kicks-ass.net> User-Agent: Mutt/1.5.24 (2015-08-30) X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-MC-Unique: 37-W3smINPiQ0aJcgrG5ag-1 X-Mimecast-Spam-Score: 0 Content-Type: text/plain; charset=WINDOWS-1252 Content-Transfer-Encoding: quoted-printable Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10/29, Peter Zijlstra wrote: > > That said, I think cgroups use a variant of percpu-rwsem that wreck rss > on purpose and always take the slowpaths. I forgot (never understodd) why does Android need this. I am wondering if it makes any sense to add a config/boot or even runtime knob for cgroup_threadgroup_rwsem. Oleg.