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=-18.2 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,FSL_HELO_FAKE, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_IN_DEF_DKIM_WL 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 14F99C64E75 for ; Thu, 26 Nov 2020 07:24:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D2C9F21D7F for ; Thu, 26 Nov 2020 07:24:12 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="JYF1Mmah" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388503AbgKZHYI (ORCPT ); Thu, 26 Nov 2020 02:24:08 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56424 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388494AbgKZHYI (ORCPT ); Thu, 26 Nov 2020 02:24:08 -0500 Received: from mail-io1-xd41.google.com (mail-io1-xd41.google.com [IPv6:2607:f8b0:4864:20::d41]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DE2BCC0613D4 for ; Wed, 25 Nov 2020 23:24:07 -0800 (PST) Received: by mail-io1-xd41.google.com with SMTP id u21so831750iol.12 for ; Wed, 25 Nov 2020 23:24:07 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:content-transfer-encoding:in-reply-to; bh=lY9WcgjRAuSB1sVe9pZbMqYNGAqE5NKeMBySD6KNPgU=; b=JYF1Mmahz+3wxs+0JH7ie0ol7o/QwIWB5CtProBINGMk6+GxuRiUnhWdAWsdikHSjN EqbXDga1k7V7YwhliWSUdlzsY2AmIWsGeuaaLKxI5mtxgAY2T6+0zx7QGm+G86+K+gD0 ZGlVSEIsvXiJ58R6J3w3mrpEJABMSWyj/icc198AbtvDzbBCo5V2bDuYKfFuU6ANQGcQ VdxVMsBDrxDNf68eLssoAbj6ma4SKGqw76oYm9YIvtKiAnOTDZqe3p4PclWdn2Zo8Kr9 Oguhq5Gb87mRKWMMwhF5kMVlRFpOSIgGdAVJ4UM4WzboJ3cWBwKktupE+MaqXQco4YBY L9mw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:content-transfer-encoding :in-reply-to; bh=lY9WcgjRAuSB1sVe9pZbMqYNGAqE5NKeMBySD6KNPgU=; b=ZHZUUSLDSnbwuNm8U00zEp5vADBluMUqV89ZS7f9qd9mLQloF+Qe6qjtc9bszwL5pW IU4in+pAyumhlar34tdUiUpDQu+sANvB50d1bV1qqTXZSvdPzvcSqrRoEWBC8bvxKb4+ eu0BXVA6ieMjL/PP8cu/9wYcCtYb7zGdj/9FA5egOjinC4I2PPXH9oeyu3p7n1/5yztj j0hlnD4GUeIAw8ijoEL6NJUb30P5Fl+rtEJjloae+cM31H9QyxHWHgsmwhTKgMvl/fhX Ji1+ZlgqNnq/9kCFpm9ZoAjrPuf5fL24w2XwjnoKYFrCBS8zoVIORm0/swln1GZoKyf+ Sa8g== X-Gm-Message-State: AOAM533l/43/m1md5CEzFjCeAhR5ksoggj3AT7vjzZWVci+yfHHyVN4m Olrybw3TzXifli/WNXf4k0yQWw== X-Google-Smtp-Source: ABdhPJzgcfvi/KBVN0+6c0Cgk2ld8KZLlmLpg5BCZ+fm4AdqaMf3bq0Ma8e86OLnbIVWm/BOgFQ2AQ== X-Received: by 2002:a02:3716:: with SMTP id r22mr2065414jar.104.1606375447069; Wed, 25 Nov 2020 23:24:07 -0800 (PST) Received: from google.com ([2620:15c:183:200:7220:84ff:fe09:2d90]) by smtp.gmail.com with ESMTPSA id i77sm284789ioa.54.2020.11.25.23.24.06 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 25 Nov 2020 23:24:06 -0800 (PST) Date: Thu, 26 Nov 2020 00:24:02 -0700 From: Yu Zhao To: Alex Shi Cc: Konstantin Khlebnikov , Andrew Morton , Hugh Dickins , Michal Hocko , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH next] mm/swap.c: reduce lock contention in lru_cache_add Message-ID: <20201126072402.GA1047005@google.com> References: <1605860847-47445-1-git-send-email-alex.shi@linux.alibaba.com> <20201126045234.GA1014081@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Nov 26, 2020 at 02:39:03PM +0800, Alex Shi wrote: > > > 在 2020/11/26 下午12:52, Yu Zhao 写道: > >> */ > >> void __pagevec_lru_add(struct pagevec *pvec) > >> { > >> - int i; > >> - struct lruvec *lruvec = NULL; > >> + int i, nr_lruvec; > >> unsigned long flags = 0; > >> + struct page *page; > >> + struct lruvecs lruvecs; > >> > >> - for (i = 0; i < pagevec_count(pvec); i++) { > >> - struct page *page = pvec->pages[i]; > >> + nr_lruvec = sort_page_lruvec(&lruvecs, pvec); > > Simply looping pvec multiple times (15 at most) for different lruvecs > > would be better because 1) it requires no extra data structures and > > therefore has better cache locality (theoretically faster) 2) it only > > loops once when !CONFIG_MEMCG and !CONFIG_NUMA and therefore has no > > impact on Android and Chrome OS. > > > > With multiple memcgs, it do help a lot, I had gotten 30% grain on readtwice > case. but yes, w/o MEMCG and NUMA, it's good to keep old behavior. So > would you like has a proposal for this? Oh, no, I'm not against your idea. I was saying it doesn't seem necessary to sort -- a nested loop would just do the job given pagevec is small. diff --git a/mm/swap.c b/mm/swap.c index cb3794e13b48..1d238edc2907 100644 --- a/mm/swap.c +++ b/mm/swap.c @@ -996,15 +996,26 @@ static void __pagevec_lru_add_fn(struct page *page, struct lruvec *lruvec) */ void __pagevec_lru_add(struct pagevec *pvec) { - int i; + int i, j; struct lruvec *lruvec = NULL; unsigned long flags = 0; for (i = 0; i < pagevec_count(pvec); i++) { struct page *page = pvec->pages[i]; + if (!page) + continue; + lruvec = relock_page_lruvec_irqsave(page, lruvec, &flags); - __pagevec_lru_add_fn(page, lruvec); + + for (j = i; j < pagevec_count(pvec); j++) { + if (page_to_nid(pvec->pages[j]) != page_to_nid(page) || + page_memcg(pvec->pages[j]) != page_memcg(page)) + continue; + + __pagevec_lru_add_fn(pvec->pages[j], lruvec); + pvec->pages[j] = NULL; + } } if (lruvec) unlock_page_lruvec_irqrestore(lruvec, flags);