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 8C6EDC433EF for ; Thu, 23 Jun 2022 16:37:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232245AbiFWQhJ (ORCPT ); Thu, 23 Jun 2022 12:37:09 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38940 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230512AbiFWQhG (ORCPT ); Thu, 23 Jun 2022 12:37:06 -0400 Received: from smtp-out2.suse.de (smtp-out2.suse.de [195.135.220.29]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 87D5345AFA; Thu, 23 Jun 2022 09:37:05 -0700 (PDT) Received: from relay2.suse.de (relay2.suse.de [149.44.160.134]) by smtp-out2.suse.de (Postfix) with ESMTP id 404BF1F38C; Thu, 23 Jun 2022 16:37:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1656002224; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=Xjy8SPQ+d5ER4berxN3l8OR04THIzep3YipbQ/OBM0g=; b=Ew+9Nb9MszfcKz8/CBOy/vbT3LdyWXYXJmxRGKgwX44dyVrdqLUM2gHRY/sEx6UyjnRIDM XzKj749fNM/8KrvLqqDkVWcOjsXB8hvCCVPr2RXCWZIpa/zrlE67nFC15urvWI1xAa1OjU AnLic47l3onMcYVNv9L25O3PWNX0d3c= Received: from suse.cz (unknown [10.100.201.86]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by relay2.suse.de (Postfix) with ESMTPS id 6AD542C197; Thu, 23 Jun 2022 16:37:03 +0000 (UTC) Date: Thu, 23 Jun 2022 18:37:02 +0200 From: Michal Hocko To: Yosry Ahmed Cc: Johannes Weiner , Roman Gushchin , Shakeel Butt , Muchun Song , Andrew Morton , Matthew Wilcox , Vlastimil Babka , David Hildenbrand , Miaohe Lin , NeilBrown , Alistair Popple , Suren Baghdasaryan , Peter Xu , Linux Kernel Mailing List , Cgroups , Linux-MM Subject: Re: [PATCH] mm: vmpressure: don't count userspace-induced reclaim as memory pressure Message-ID: References: <20220623000530.1194226-1-yosryahmed@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu 23-06-22 09:22:35, Yosry Ahmed wrote: > On Thu, Jun 23, 2022 at 2:43 AM Michal Hocko wrote: > > > > On Thu 23-06-22 01:35:59, Yosry Ahmed wrote: [...] > > > In our internal version of memory.reclaim that we recently upstreamed, > > > we do not account vmpressure during proactive reclaim (similar to how > > > psi is handled upstream). We want to make sure this behavior also > > > exists in the upstream version so that consolidating them does not > > > break our users who rely on vmpressure and will start seeing increased > > > pressure due to proactive reclaim. > > > > These are good reasons to have this patch in your tree. But why is this > > patch benefitial for the upstream kernel? It clearly adds some code and > > some special casing which will add a maintenance overhead. > > It is not just Google, any existing vmpressure users will start seeing > false pressure notifications with memory.reclaim. The main goal of the > patch is to make sure memory.reclaim does not break pre-existing users > of vmpressure, and doing it in a way that is consistent with psi makes > sense. memory.reclaim is v2 only feature which doesn't have vmpressure interface. So I do not see how pre-existing users of the upstream kernel can see any breakage. -- Michal Hocko SUSE Labs