From mboxrd@z Thu Jan 1 00:00:00 1970 From: Rik van Riel Subject: Re: [patch 2/2] MM: allow per-cpu vmstat_threshold and vmstat_worker configuration Date: Tue, 25 Apr 2017 15:29:06 -0400 Message-ID: <1493148546.31102.1.camel@redhat.com> References: <20170425135717.375295031@redhat.com> <20170425135846.203663532@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8bit Cc: Luiz Capitulino , Linux RT Users To: Marcelo Tosatti , linux-kernel@vger.kernel.org, linux-mm@kvack.org Return-path: In-Reply-To: <20170425135846.203663532@redhat.com> Sender: owner-linux-mm@kvack.org List-Id: linux-rt-users.vger.kernel.org On Tue, 2017-04-25 at 10:57 -0300, Marcelo Tosatti wrote: > The per-CPU vmstat worker is a problem on -RT workloads (because > ideally the CPU is entirely reserved for the -RT app, without > interference). The worker transfers accumulated per-CPU  > vmstat counters to global counters. > > To resolve the problem, create two tunables: > > * Userspace configurable per-CPU vmstat threshold: by default the  > VM code calculates the size of the per-CPU vmstat arrays. This  > tunable allows userspace to configure the values. > > * Userspace configurable per-CPU vmstat worker: allow disabling > the per-CPU vmstat worker. > > The patch below contains documentation which describes the tunables > in more detail. The documentation says what the tunables do, but not how you should set them in different scenarios, or why. That could be a little more helpful to sysadmins. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org