From mboxrd@z Thu Jan 1 00:00:00 1970 From: Michal Hocko Subject: Re: [RESEND PATCH 1/2 -mm] mm: account lazy free pages separately Date: Wed, 14 Aug 2019 14:53:34 +0200 Message-ID: <20190814125334.GX17933@dhcp22.suse.cz> References: <1565308665-24747-1-git-send-email-yang.shi@linux.alibaba.com> <20190809083216.GM18351@dhcp22.suse.cz> <1a3c4185-c7ab-8d6f-8191-77dce02025a7@linux.alibaba.com> <20190809180238.GS18351@dhcp22.suse.cz> <79c90f6b-fcac-02e1-015a-0eaa4eafdf7d@linux.alibaba.com> <564a0860-94f1-6301-5527-5c2272931d8b@suse.cz> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <564a0860-94f1-6301-5527-5c2272931d8b@suse.cz> Sender: linux-kernel-owner@vger.kernel.org To: Vlastimil Babka Cc: Yang Shi , kirill.shutemov@linux.intel.com, hannes@cmpxchg.org, rientjes@google.com, akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Linux API List-Id: linux-api@vger.kernel.org On Wed 14-08-19 14:49:18, Vlastimil Babka wrote: > On 8/9/19 8:26 PM, Yang Shi wrote: > > Here the new counter is introduced for patch 2/2 to account deferred > > split THPs into available memory since NR_ANON_THPS may contain > > non-deferred split THPs. > > > > I could use an internal counter for deferred split THPs, but if it is > > accounted by mod_node_page_state, why not just show it in /proc/meminfo? > > The answer to "Why not" is that it becomes part of userspace API (btw this > patchset should have CC'd linux-api@ - please do for further iterations) and > even if the implementation detail of deferred splitting might change in the > future, we'll basically have to keep the counter (even with 0 value) in > /proc/meminfo forever. > > Also, quite recently we have added the following counter: > > KReclaimable: Kernel allocations that the kernel will attempt to reclaim > under memory pressure. Includes SReclaimable (below), and other > direct allocations with a shrinker. > > Although THP allocations are not exactly "kernel allocations", once they are > unmapped, they are in fact kernel-only, so IMHO it wouldn't be a big stretch to > add the lazy THP pages there? That would indeed fit in much better than a dedicated counter. -- Michal Hocko SUSE Labs