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 D42DDC43217 for ; Fri, 25 Mar 2022 01:33:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1357472AbiCYBew (ORCPT ); Thu, 24 Mar 2022 21:34:52 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38368 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1357517AbiCYBdP (ORCPT ); Thu, 24 Mar 2022 21:33:15 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E3489BF959 for ; Thu, 24 Mar 2022 18:31:34 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 84A2CB8261B for ; Fri, 25 Mar 2022 01:31:34 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1EE39C340ED; Fri, 25 Mar 2022 01:31:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1648171893; bh=KD05JJkCfDXGpXza8vdvevWmL9YwNBA0eelXHgvEXdI=; h=Date:To:From:Subject:From; b=FX0dq49Oax1ILWgQAZ+NDJ0cX1+AorYokI7FR0uoPYg+zPMBxewNbjTjbk8RYpnNx IZu6lgSK2QDAfajPK0ALWL14CaPeSTtfSIPvpHT1lmFKOshxDq6KnnO2s2K2ZV4AmY hdrmvVHCOhSefcC7U6+jeh5T41SCP4OkOZxFCNQo= Date: Thu, 24 Mar 2022 18:31:32 -0700 To: mm-commits@vger.kernel.org, timmurray@google.com, shakeelb@google.com, roman.gushchin@linux.dev, pmladek@suse.com, peterz@infradead.org, minchan@kernel.org, mhocko@suse.com, hannes@cmpxchg.org, surenb@google.com, akpm@linux-foundation.org From: Andrew Morton Subject: [merged] mm-count-time-in-drain_all_pages-during-direct-reclaim-as-memory-pressure.patch removed from -mm tree Message-Id: <20220325013133.1EE39C340ED@smtp.kernel.org> Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org The patch titled Subject: mm: count time in drain_all_pages during direct reclaim as memory pressure has been removed from the -mm tree. Its filename was mm-count-time-in-drain_all_pages-during-direct-reclaim-as-memory-pressure.patch This patch was dropped because it was merged into mainline or a subsystem tree ------------------------------------------------------ From: Suren Baghdasaryan Subject: mm: count time in drain_all_pages during direct reclaim as memory pressure When page allocation in direct reclaim path fails, the system will make one attempt to shrink per-cpu page lists and free pages from high alloc reserves. Draining per-cpu pages into buddy allocator can be a very slow operation because it's done using workqueues and the task in direct reclaim waits for all of them to finish before proceeding. Currently this time is not accounted as psi memory stall. While testing mobile devices under extreme memory pressure, when allocations are failing during direct reclaim, we notices that psi events which would be expected in such conditions were not triggered. After profiling these cases it was determined that the reason for missing psi events was that a big chunk of time spent in direct reclaim is not accounted as memory stall, therefore psi would not reach the levels at which an event is generated. Further investigation revealed that the bulk of that unaccounted time was spent inside drain_all_pages call. A typical captured case when drain_all_pages path gets activated: __alloc_pages_slowpath took 44.644.613ns __perform_reclaim took 751.668ns (1.7%) drain_all_pages took 43.887.167ns (98.3%) PSI in this case records the time spent in __perform_reclaim but ignores drain_all_pages, IOW it misses 98.3% of the time spent in __alloc_pages_slowpath. Annotate __alloc_pages_direct_reclaim in its entirety so that delays from handling page allocation failure in the direct reclaim path are accounted as memory stall. Link: https://lkml.kernel.org/r/20220223194812.1299646-1-surenb@google.com Signed-off-by: Suren Baghdasaryan Reported-by: Tim Murray Acked-by: Johannes Weiner Acked-by: Michal Hocko Reviewed-by: Shakeel Butt Cc: Petr Mladek Cc: Peter Zijlstra Cc: Roman Gushchin Cc: Minchan Kim Signed-off-by: Andrew Morton --- mm/page_alloc.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) --- a/mm/page_alloc.c~mm-count-time-in-drain_all_pages-during-direct-reclaim-as-memory-pressure +++ a/mm/page_alloc.c @@ -4554,13 +4554,12 @@ __perform_reclaim(gfp_t gfp_mask, unsign const struct alloc_context *ac) { unsigned int noreclaim_flag; - unsigned long pflags, progress; + unsigned long progress; cond_resched(); /* We now go into synchronous reclaim */ cpuset_memory_pressure_bump(); - psi_memstall_enter(&pflags); fs_reclaim_acquire(gfp_mask); noreclaim_flag = memalloc_noreclaim_save(); @@ -4569,7 +4568,6 @@ __perform_reclaim(gfp_t gfp_mask, unsign memalloc_noreclaim_restore(noreclaim_flag); fs_reclaim_release(gfp_mask); - psi_memstall_leave(&pflags); cond_resched(); @@ -4583,11 +4581,13 @@ __alloc_pages_direct_reclaim(gfp_t gfp_m unsigned long *did_some_progress) { struct page *page = NULL; + unsigned long pflags; bool drained = false; + psi_memstall_enter(&pflags); *did_some_progress = __perform_reclaim(gfp_mask, order, ac); if (unlikely(!(*did_some_progress))) - return NULL; + goto out; retry: page = get_page_from_freelist(gfp_mask, order, alloc_flags, ac); @@ -4603,6 +4603,8 @@ retry: drained = true; goto retry; } +out: + psi_memstall_leave(&pflags); return page; } _ Patches currently in -mm which might be from surenb@google.com are