From mboxrd@z Thu Jan 1 00:00:00 1970 From: Matthew Wilcox Subject: Re: [RFC PATCH 0/8] memcg: Enable fine-grained per process memory control Date: Tue, 18 Aug 2020 13:55:59 +0100 Message-ID: <20200818125559.GP17456@casper.infradead.org> References: <20200817140831.30260-1-longman@redhat.com> <20200818091453.GL2674@hirez.programming.kicks-ass.net> <20200818092737.GA148695@chrisdown.name> <20200818100444.GN2674@hirez.programming.kicks-ass.net> Mime-Version: 1.0 Return-path: DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=Mnr9o5vomenMnjGSwOgADsZNSiDQs16XxuJQkA6pw7A=; b=pUGj2IxnkHV9vZueIpbwqji2Jz 4osZe4zjTl6vy8j4O1GqSzuht1xZTlDq/nyo7Zt88MLI0EF3+bRsp7khSHVkul6jXPUt6jbUcGgqX wB2TcbFBTZRD44Iz4OBsNLp9tT2pWHDXZxgDCYE1sqJxFC8/2qUdR7Gr5kHMA+fihdG3Xd3EPQgs3 1Yi3ukQgtyCHWgNKqxRmqGQFa7YJ77FBhxgwcSBJ0sTftYxwm0Zr5Kz0hFwQ+NrV3N+Gfdg3tiPoG TFHH6wJpI5/01cnU9Z5jhHgml1eM1Aji19CV+ORA8lxPNw/zaz+KJse0bAZLt4mKIZPP3ziA3p9kW bOdS3v4g==; Content-Disposition: inline In-Reply-To: <20200818100444.GN2674-Nxj+rRp3nVydTX5a5knrm8zTDFooKrT+cvkQGrU6aU0@public.gmane.org> Sender: cgroups-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: peterz-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org Cc: Chris Down , Waiman Long , Andrew Morton , Johannes Weiner , Michal Hocko , Vladimir Davydov , Jonathan Corbet , Alexey Dobriyan , Ingo Molnar , Juri Lelli , Vincent Guittot , linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-doc-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-fsdevel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org On Tue, Aug 18, 2020 at 12:04:44PM +0200, peterz-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org wrote: > On Tue, Aug 18, 2020 at 10:27:37AM +0100, Chris Down wrote: > > peterz-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org writes: > > > On Mon, Aug 17, 2020 at 10:08:23AM -0400, Waiman Long wrote: > > > > Memory controller can be used to control and limit the amount of > > > > physical memory used by a task. When a limit is set in "memory.high" in > > > > a v2 non-root memory cgroup, the memory controller will try to reclaim > > > > memory if the limit has been exceeded. Normally, that will be enough > > > > to keep the physical memory consumption of tasks in the memory cgroup > > > > to be around or below the "memory.high" limit. > > > > > > > > Sometimes, memory reclaim may not be able to recover memory in a rate > > > > that can catch up to the physical memory allocation rate. In this case, > > > > the physical memory consumption will keep on increasing. > > > > > > Then slow down the allocator? That's what we do for dirty pages too, we > > > slow down the dirtier when we run against the limits. > > > > We already do that since v5.4. I'm wondering whether Waiman's customer is > > just running with a too-old kernel without 0e4b01df865 ("mm, memcg: throttle > > allocators when failing reclaim over memory.high") backported. > > That commit is fundamentally broken, it doesn't guarantee anything. > > Please go read how the dirty throttling works (unless people wrecked > that since..). Of course they did. https://lore.kernel.org/linux-mm/ce7975cd-6353-3f29-b52c-7a81b1d07caa-tSWWG44O7X1aa/9Udqfwiw@public.gmane.org/