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 X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 70281C433E0 for ; Thu, 4 Jun 2020 21:43:51 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 226FB2074B for ; Thu, 4 Jun 2020 21:43:51 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="r8aUrwNb" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 226FB2074B Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id A359880007; Thu, 4 Jun 2020 17:43:50 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 9E5EA8E0006; Thu, 4 Jun 2020 17:43:50 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 8F9E780007; Thu, 4 Jun 2020 17:43:50 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0210.hostedemail.com [216.40.44.210]) by kanga.kvack.org (Postfix) with ESMTP id 76DD48E0006 for ; Thu, 4 Jun 2020 17:43:50 -0400 (EDT) Received: from smtpin21.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id 2EABE824556B for ; Thu, 4 Jun 2020 21:43:50 +0000 (UTC) X-FDA: 76892857020.21.glue29_4e0e15726d9a Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin21.hostedemail.com (Postfix) with ESMTP id 19163180442C2 for ; Thu, 4 Jun 2020 21:43:50 +0000 (UTC) X-HE-Tag: glue29_4e0e15726d9a X-Filterd-Recvd-Size: 5349 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf35.hostedemail.com (Postfix) with ESMTP for ; Thu, 4 Jun 2020 21:43:49 +0000 (UTC) Received: from localhost.localdomain (c-73-231-172-41.hsd1.ca.comcast.net [73.231.172.41]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 5AB442067B; Thu, 4 Jun 2020 21:43:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1591307028; bh=NrT7kxPJZH9oq0NI7hXVoXdbIA1zZsJXsd3+en/OdUk=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=r8aUrwNbHRix1KcN/0gp2RjDKP6AUB88k/5FTg4dFXc6HUQjUPB0cTVS6vvLoLDhV FVvDfS1pPkJwnLSAbcQq4yJKIXEP4oMXG3E5dDz7cylvZMkcj6G0wTD0LDPHf3hp6d Ay4t4J92gQ7iRig2XwcJxKCWT/ln2zvfWfTec4Mg= Date: Thu, 4 Jun 2020 14:43:47 -0700 From: Andrew Morton To: Charan Teja Reddy Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, vinmenon@codeaurora.org Subject: Re: [PATCH] mm, page_alloc: skip ->waternark_boost for atomic order-0 allocations Message-Id: <20200604144347.7804bc81bbd6dd3027a1cb10@linux-foundation.org> In-Reply-To: <1589882284-21010-1-git-send-email-charante@codeaurora.org> References: <1589882284-21010-1-git-send-email-charante@codeaurora.org> X-Mailer: Sylpheed 3.5.1 (GTK+ 2.24.31; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 19163180442C2 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam04 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Tue, 19 May 2020 15:28:04 +0530 Charan Teja Reddy wrote: > When boosting is enabled, it is observed that rate of atomic order-0 > allocation failures are high due to the fact that free levels in the > system are checked with ->watermark_boost offset. This is not a problem > for sleepable allocations but for atomic allocations which looks like > regression. > > This problem is seen frequently on system setup of Android kernel > running on Snapdragon hardware with 4GB RAM size. When no extfrag event > occurred in the system, ->watermark_boost factor is zero, thus the > watermark configurations in the system are: > _watermark = ( > [WMARK_MIN] = 1272, --> ~5MB > [WMARK_LOW] = 9067, --> ~36MB > [WMARK_HIGH] = 9385), --> ~38MB > watermark_boost = 0 > > After launching some memory hungry applications in Android which can > cause extfrag events in the system to an extent that ->watermark_boost > can be set to max i.e. default boost factor makes it to 150% of high > watermark. > _watermark = ( > [WMARK_MIN] = 1272, --> ~5MB > [WMARK_LOW] = 9067, --> ~36MB > [WMARK_HIGH] = 9385), --> ~38MB > watermark_boost = 14077, -->~57MB > > With default system configuration, for an atomic order-0 allocation to > succeed, having free memory of ~2MB will suffice. But boosting makes > the min_wmark to ~61MB thus for an atomic order-0 allocation to be > successful system should have minimum of ~23MB of free memory(from > calculations of zone_watermark_ok(), min = 3/4(min/2)). But failures are > observed despite system is having ~20MB of free memory. In the testing, > this is reproducible as early as first 300secs since boot and with > furtherlowram configurations(<2GB) it is observed as early as first > 150secs since boot. > > These failures can be avoided by excluding the ->watermark_boost in > watermark caluculations for atomic order-0 allocations. Do we have any additional reviewer input on this one? > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -3709,6 +3709,18 @@ static bool zone_allows_reclaim(struct zone *local_zone, struct zone *zone) > } > > mark = wmark_pages(zone, alloc_flags & ALLOC_WMARK_MASK); > + /* > + * Allow GFP_ATOMIC order-0 allocations to exclude the > + * zone->watermark_boost in its watermark calculations. > + * We rely on the ALLOC_ flags set for GFP_ATOMIC > + * requests in gfp_to_alloc_flags() for this. Reason not to > + * use the GFP_ATOMIC directly is that we want to fall back > + * to slow path thus wake up kswapd. > + */ > + if (unlikely(!order && !(alloc_flags & ALLOC_WMARK_MASK) && > + (alloc_flags & (ALLOC_HARDER | ALLOC_HIGH)))) { > + mark = zone->_watermark[WMARK_MIN]; > + } > if (!zone_watermark_fast(zone, order, mark, > ac->highest_zoneidx, alloc_flags)) { > int ret; It would seem smart to do --- a/mm/page_alloc.c~mm-page_alloc-skip-waternark_boost-for-atomic-order-0-allocations-fix +++ a/mm/page_alloc.c @@ -3745,7 +3745,6 @@ retry: } } - mark = wmark_pages(zone, alloc_flags & ALLOC_WMARK_MASK); /* * Allow GFP_ATOMIC order-0 allocations to exclude the * zone->watermark_boost in their watermark calculations. @@ -3757,6 +3756,8 @@ retry: if (unlikely(!order && !(alloc_flags & ALLOC_WMARK_MASK) && (alloc_flags & (ALLOC_HARDER | ALLOC_HIGH)))) { mark = zone->_watermark[WMARK_MIN]; + } else { + mark = wmark_pages(zone, alloc_flags & ALLOC_WMARK_MASK); } if (!zone_watermark_fast(zone, order, mark, ac->highest_zoneidx, alloc_flags)) { but that makes page_alloc.o 16 bytes larger, so I guess don't bother.