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 40050C433EF for ; Sun, 20 Feb 2022 16:52:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S243341AbiBTQxN (ORCPT ); Sun, 20 Feb 2022 11:53:13 -0500 Received: from mxb-00190b01.gslb.pphosted.com ([23.128.96.19]:52672 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235584AbiBTQxM (ORCPT ); Sun, 20 Feb 2022 11:53:12 -0500 Received: from mail-yb1-xb30.google.com (mail-yb1-xb30.google.com [IPv6:2607:f8b0:4864:20::b30]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 34541237F8 for ; Sun, 20 Feb 2022 08:52:50 -0800 (PST) Received: by mail-yb1-xb30.google.com with SMTP id v186so29685929ybg.1 for ; Sun, 20 Feb 2022 08:52:50 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=MA9Whiv3uv/Z2j9b1Sp/UPbzEqBjJrCbfpHQf8ZeIVI=; b=CbG3cLeW89/CEqBp3kqySp+WTHTX48hBg44IsjG1Y9p+gAtOhOROjhrjTZK8DmoSkc Pfa3nLH3j5oyFdP9VO9ThumdzbCzy0ljIgpOsq4Y74Y1ACv2qBFWoJijBwu9TGRiAO8c FK9adg2triBntH1UXky8WEgn1wTgwOR9ZWiQ/OoNhAEcqy456YsmDpd2/+iqsN7AzwLM WOKcA65D+aNV6IcK6RJzPKeM5b9qHLmD5A6GPU69JrtLQoE7wlG57myAIwkYwuww3Ino YjYsLjQ/TmFfXvgmfGRIE6JUTeR7Psv59oqhZTd6h1o1L8F2Za4i3SQeZYxKUnUdQMYv jXpA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=MA9Whiv3uv/Z2j9b1Sp/UPbzEqBjJrCbfpHQf8ZeIVI=; b=FpNTGLWldNLKArPJUudPwuNIhMB3G1PnBYRRTmsRoDZpybPHm7R1/ZIti2aJd6VD62 5GSgKrUNY/CsD7eVE7ym1AoPoFCCU/sH2Fc4NguomC5d4YNSB/Sd3KfGoFtK2QZDFbpb U+xgzDJQ3mAAuXexat3cZluyZfZKSOb5Ev2jFczH5K3mGnCoVa4IFj2dOEcm9cAGsXsE HrmVyhqFwjFTXAljhEMA/JI+7Bj7rM5n0a7u6Ld0L6sqtwkSZB4GNbQhfy2YjwR7hU+6 8KQqpYGdVRQ20yayg09WOc7nkd68HE++UVBAB2AMzfQBzcDr9urHDL8bcE3ea+PP8Bp6 SQ3Q== X-Gm-Message-State: AOAM530IIRNWWbIHNQG45G88BtQD6fB3sOwl9tZyM4QCZjsdkUyeM8Qs 87kJ376SLR9dzgEUcYJZThr2L7KoDqEaVl7KkqFhCw== X-Google-Smtp-Source: ABdhPJziD5LuicOYbpCGsTty/VQuCP14Ce8qOpqdwkwSdELHVWtwSV5mL678pxcM15MhcX/4znkByKE8eyLRgcoljE0= X-Received: by 2002:a25:da47:0:b0:61d:9af4:c834 with SMTP id n68-20020a25da47000000b0061d9af4c834mr15983902ybf.441.1645375969048; Sun, 20 Feb 2022 08:52:49 -0800 (PST) MIME-Version: 1.0 References: <20220219174940.2570901-1-surenb@google.com> In-Reply-To: From: Suren Baghdasaryan Date: Sun, 20 Feb 2022 08:52:38 -0800 Message-ID: Subject: Re: [PATCH 1/1] mm: count time in drain_all_pages during direct reclaim as memory pressure To: Minchan Kim Cc: akpm@linux-foundation.org, hannes@cmpxchg.org, mhocko@suse.com, peterz@infradead.org, guro@fb.com, shakeelb@google.com, timmurray@google.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, kernel-team@android.com Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Feb 19, 2022 at 4:40 PM Minchan Kim wrote: > > On Sat, Feb 19, 2022 at 09:49:40AM -0800, Suren Baghdasaryan wrote: > > 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 > > Yes, drain_all_pages is serious slow(100ms - 150ms on Android) > especially when CPUs are fully packed. It was also spotted in CMA > allocation even when there was on no memory pressure. Thanks for the input, Minchan! In my tests I've seen 50-60ms delays in a single drain_all_pages but I can imagine there are cases worse than these. > > > proceeding. Currently this time is not accounted as psi memory stall. > > Good spot. > > > > > 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. > > > > Annotate drain_all_pages and unreserve_highatomic_pageblock during > > page allocation failure in the direct reclaim path so that delays > > caused by these calls are accounted as memory stall. > > > > Reported-by: Tim Murray > > Signed-off-by: Suren Baghdasaryan > > --- > > mm/page_alloc.c | 4 ++++ > > 1 file changed, 4 insertions(+) > > > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > > index 3589febc6d31..7fd0d392b39b 100644 > > --- a/mm/page_alloc.c > > +++ b/mm/page_alloc.c > > @@ -4639,8 +4639,12 @@ __alloc_pages_direct_reclaim(gfp_t gfp_mask, unsigned int order, > > * Shrink them and try again > > */ > > if (!page && !drained) { > > + unsigned long pflags; > > + > > + psi_memstall_enter(&pflags); > > unreserve_highatomic_pageblock(ac, false); > > drain_all_pages(NULL); > > + psi_memstall_leave(&pflags); > > Instead of annotating the specific drain_all_pages, how about > moving the annotation from __perform_reclaim to > __alloc_pages_direct_reclaim? I'm fine with that approach too. Let's wait for Johannes' input before I make any changes. Thanks, Suren.