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=-13.5 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham 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 3920AC63697 for ; Thu, 19 Nov 2020 12:56:12 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 69AE62468B for ; Thu, 19 Nov 2020 12:56:11 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="Tn6FvpBr" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 69AE62468B Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 916DC6B005D; Thu, 19 Nov 2020 07:56:10 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 8C56B6B0068; Thu, 19 Nov 2020 07:56:10 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 740E76B006C; Thu, 19 Nov 2020 07:56:10 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0055.hostedemail.com [216.40.44.55]) by kanga.kvack.org (Postfix) with ESMTP id 47ABE6B005D for ; Thu, 19 Nov 2020 07:56:10 -0500 (EST) Received: from smtpin22.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id E529D181AEF2A for ; Thu, 19 Nov 2020 12:56:09 +0000 (UTC) X-FDA: 77501165658.22.birth54_2514a2327343 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin22.hostedemail.com (Postfix) with ESMTP id B465718036FE5 for ; Thu, 19 Nov 2020 12:56:09 +0000 (UTC) X-HE-Tag: birth54_2514a2327343 X-Filterd-Recvd-Size: 5391 Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) by imf39.hostedemail.com (Postfix) with ESMTP for ; Thu, 19 Nov 2020 12:56:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=sWbrc4VvF/o948WHuvCmfd0y3g9QMiU9AieEM9zFY14=; b=Tn6FvpBrFUTga/6Eh9JSuaROM5 z4rbME/IGJZPoxtm5TQ4bhIx518j2Pnbjp4UI0yFU3py6SOI7/qFtqv/hR97icQqDcyNR0Nd1dw3A c9ElpP4PJPYTnwMKhheneq3tlpjO+kqkq2RFsmFM/wLXKEoeXKHIFBTYbOUZWvI7m6loy+2R2+oDd 3+CS3gjoqyuvyHhvBvi37wBV41Bd367YHnTXys/XMoh2z6/zyBLAKwe9nkmf4ouEMnD5HQsglssy0 HucI9NXU8dQcA3AROQRBDmSPTmi4W8gosQGSDOy8l9RsV359Fu1us6WmeXPKFNlx0bokqeKl5oiTK lbLC40wA==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1kfjTl-00029L-GU; Thu, 19 Nov 2020 12:56:01 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 5E51E3060AE; Thu, 19 Nov 2020 13:55:57 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 2B2FB2009C627; Thu, 19 Nov 2020 13:55:57 +0100 (CET) Date: Thu, 19 Nov 2020 13:55:57 +0100 From: Peter Zijlstra To: Zhaoyang Huang Cc: Zhaoyang Huang , Ingo Molnar , linux-mm@kvack.org, linux-kernel@vger.kernel.org, hannes@cmpxchg.org Subject: Re: [RFC PATCH] mm: bail out from psi memstall when cond_resched Message-ID: <20201119125557.GM3121392@hirez.programming.kicks-ass.net> References: <1605669776-24242-1-git-send-email-zhaoyang.huang@unisoc.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1605669776-24242-1-git-send-email-zhaoyang.huang@unisoc.com> 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 Wed, Nov 18, 2020 at 11:22:56AM +0800, Zhaoyang Huang wrote: > Memory reclaiming will run as several seconds in memory constraint system, which > will be deemed as heavy memstall. Have the memory reclaim be more presiced by > bailing out when cond_resched How is this supposed to work on PREEMPT=y where cond_resched() is a NOP and you can get preempted at any random point? (leaving the rest for Johannes) > Signed-off-by: Zhaoyang Huang > --- > mm/vmscan.c | 23 ++++++++++++++++------- > 1 file changed, 16 insertions(+), 7 deletions(-) > > diff --git a/mm/vmscan.c b/mm/vmscan.c > index a815f73..a083c85 100644 > --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -316,6 +316,15 @@ static inline bool memcg_congested(struct pglist_data *pgdat, > } > #endif > > +static inline void psi_cond_resched(void) > +{ > + unsigned long *flags; > + > + if (current->flags & PF_MEMSTALL) > + psi_memstall_leave(&flags); > + cond_resched(); > + psi_memstall_enter(&flags); > +} > /* > * This misses isolated pages which are not accounted for to save counters. > * As the data only determines if reclaim or compaction continues, it is > @@ -557,7 +566,7 @@ static unsigned long do_shrink_slab(struct shrink_control *shrinkctl, > total_scan -= shrinkctl->nr_scanned; > scanned += shrinkctl->nr_scanned; > > - cond_resched(); > + psi_cond_resched(); > } > > if (next_deferred >= scanned) > @@ -714,7 +723,7 @@ static unsigned long shrink_slab(gfp_t gfp_mask, int nid, > > up_read(&shrinker_rwsem); > out: > - cond_resched(); > + psi_cond_resched(); > return freed; > } > > @@ -1109,7 +1118,7 @@ static unsigned long shrink_page_list(struct list_head *page_list, > unsigned nr_reclaimed = 0; > > memset(stat, 0, sizeof(*stat)); > - cond_resched(); > + psi_cond_resched(); > > while (!list_empty(page_list)) { > struct address_space *mapping; > @@ -1118,7 +1127,7 @@ static unsigned long shrink_page_list(struct list_head *page_list, > enum page_references references = PAGEREF_RECLAIM_CLEAN; > bool dirty, writeback; > > - cond_resched(); > + psi_cond_resched(); > > page = lru_to_page(page_list); > list_del(&page->lru); > @@ -2084,7 +2093,7 @@ static void shrink_active_list(unsigned long nr_to_scan, > spin_unlock_irq(&pgdat->lru_lock); > > while (!list_empty(&l_hold)) { > - cond_resched(); > + psi_cond_resched(); > page = lru_to_page(&l_hold); > list_del(&page->lru); > > @@ -2500,7 +2509,7 @@ static void shrink_node_memcg(struct pglist_data *pgdat, struct mem_cgroup *memc > } > } > > - cond_resched(); > + psi_cond_resched(); > > if (nr_reclaimed < nr_to_reclaim || scan_adjusted) > continue; > @@ -4149,7 +4158,7 @@ static int __node_reclaim(struct pglist_data *pgdat, gfp_t gfp_mask, unsigned in > .reclaim_idx = gfp_zone(gfp_mask), > }; > > - cond_resched(); > + psi_cond_resched(); > fs_reclaim_acquire(sc.gfp_mask); > /* > * We need to be able to allocate from the reserves for RECLAIM_UNMAP > -- > 1.9.1 >