From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pablo Neira Ayuso Subject: Re: [PATCH] netfilter: conntrack: use power efficient workqueue Date: Mon, 6 Nov 2017 16:25:33 +0100 Message-ID: <20171106152533.GA27072@salvia> References: <1509635767-12253-1-git-send-email-vincent.guittot@linaro.org> <20171106143155.GA8738@salvia> <20171106145632.GA20091@salvia> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: netfilter-devel@vger.kernel.org To: Vincent Guittot Return-path: Received: from mail.us.es ([193.147.175.20]:45912 "EHLO mail.us.es" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753921AbdKFPZq (ORCPT ); Mon, 6 Nov 2017 10:25:46 -0500 Received: from antivirus1-rhel7.int (unknown [192.168.2.11]) by mail.us.es (Postfix) with ESMTP id 306051BCFC2 for ; Mon, 6 Nov 2017 16:25:45 +0100 (CET) Received: from antivirus1-rhel7.int (localhost [127.0.0.1]) by antivirus1-rhel7.int (Postfix) with ESMTP id 20796DA871 for ; Mon, 6 Nov 2017 16:25:45 +0100 (CET) Content-Disposition: inline In-Reply-To: Sender: netfilter-devel-owner@vger.kernel.org List-ID: On Mon, Nov 06, 2017 at 04:15:42PM +0100, Vincent Guittot wrote: > Hi Pablo, > > On 6 November 2017 at 15:56, Pablo Neira Ayuso wrote: > > On Mon, Nov 06, 2017 at 03:31:55PM +0100, Pablo Neira Ayuso wrote: > >> On Thu, 2 Nov 2017 15:16:07 +0100 Vincent Guittot wrote: > >> > conntrack uses the bounded system_long_wq workqueue for its works that > >> > don't have to run on the cpu they have been queued. Using bounded > >> > workqueue prevents the scheduler to make smart decision about the best > >> > place to schedule the work. > >> > > >> > This patch replaces system_long_wq with system_power_efficient_wq. > >> > the work stays bounded to a cpu by default unless the > >> > CONFIG_WQ_POWER_EFFICIENT is enable. In the latter case, the work can > >> > be scheduled on the best cpu from a power or a performance point of > >> > view. > >> > >> Applied, thanks. > > > > I'm stepping back. According to what I'm reading > > system_power_efficient_wq becomes system_wq when disabled, which is > > not semantically the same as system_long_wq that we have now. > > When disabled, system_power_efficient_wq behaves like system_wq (and > system_long_wq) as the worqueue are bounded to a cpu but It stays a > different workqueue. > > > My concern is that the conntrack garbage collector may run for quite a > > bit of time. Did you test this with a large conntrack table full of > > No, I haven't done specific tests with a large conntrack table full of entries. > > There is no system_power_efficient_long_wq. I was not convinced that > we should create one that's why I have used system_power_efficient_wq My concern is that this garbage collector may run intensively on busy conntrack tables to get rid of expired entries, so my question is if switching from system_long_wq to system_wq is a real issue. Thanks.