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=-9.6 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS autolearn=unavailable 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 63CA2C388F2 for ; Mon, 2 Nov 2020 13:44:54 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id D2392223BD for ; Mon, 2 Nov 2020 13:44:53 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="HqtjOjV0" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D2392223BD Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 180946B005D; Mon, 2 Nov 2020 08:44:53 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 10A966B006E; Mon, 2 Nov 2020 08:44:53 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id EED1C6B0070; Mon, 2 Nov 2020 08:44:52 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0052.hostedemail.com [216.40.44.52]) by kanga.kvack.org (Postfix) with ESMTP id C02C86B005D for ; Mon, 2 Nov 2020 08:44:52 -0500 (EST) Received: from smtpin27.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 5B5F11EE6 for ; Mon, 2 Nov 2020 13:44:52 +0000 (UTC) X-FDA: 77439598824.27.day54_320aaa9272b0 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin27.hostedemail.com (Postfix) with ESMTP id 2F7433D66B for ; Mon, 2 Nov 2020 13:44:52 +0000 (UTC) X-HE-Tag: day54_320aaa9272b0 X-Filterd-Recvd-Size: 4799 Received: from mail-io1-f65.google.com (mail-io1-f65.google.com [209.85.166.65]) by imf10.hostedemail.com (Postfix) with ESMTP for ; Mon, 2 Nov 2020 13:44:51 +0000 (UTC) Received: by mail-io1-f65.google.com with SMTP id r9so14965804ioo.7 for ; Mon, 02 Nov 2020 05:44:51 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=cEmtsbdHqC4I+5fjYJ4G6hPGEzEHqNgzPZHsu1Q5zg4=; b=HqtjOjV0zxhZexN2cFiIHJOI6PbtrCk33lKM2c6LqOMzVhxYCOLdqvY5lqSZRtMWgY T4NgDMcXkOfpLLIDnhtWatS9TES/3hH1ABnf4OLPVFfEEhKyVVzqUBtvL9PC9Labvsw+ ECdD6emjwnJOtp3tXmTnU/FxiNMeR35cwkpC0GpJYkMZ4kJdAF3CPeGJ+gACUfx7MF5X 59sVScjfS8DKSq9IC3/C40AWByOCx5BW+Z4Bmvul3/LXXI240kKpe+XjkGXIejrkIIJz pn+/uH6Wn/KEhWqPCFAKeC0OPHTpkAybC+cHNvhpsQjQ0tOoy5BqZPbZJsEPE27s4lOe /fhw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=cEmtsbdHqC4I+5fjYJ4G6hPGEzEHqNgzPZHsu1Q5zg4=; b=kaxFhKzqDGE/jSza2AdFu01glEJ+GogKw0ZeW+t82sJsovnwvC40stFyl7lZ83QWtt XhGuoc0ilJU57Tu5Ad/0rY5DZmIldvDsAFoTAQvisgX/NyK2i6AlKlN5adqsQ4HFrlId y68duZ4LsNLhOVg+lYDNwS1l+LhUsGUqaoDab8ppnIkLloROijXum23CCs+Ekm/ZT8Xp yt5UF37MaS6X99N0pqXUKeiL9ssixNLNoAwvPml26U50hyOr6ypNwYT+jVZ3A65vzTke UcqFqXmzRfHJXKsFXjXXc12Ps6DYwlizggbMnvkg0DedAgsHxadv2FUqJpaEpP4qyKb1 51TQ== X-Gm-Message-State: AOAM530VnjfSPssa1gUjiExgz9/FbRtQVRUDE8uxJv+cmAhJgrs0zvI1 1Wfowq8ScecOVfmedKzt5dWY49P/ON/hxvvf0PY= X-Google-Smtp-Source: ABdhPJyDkcGCR51lzq2gNFwGY9/fzfqgodyPlOs/h+p/gvOLefUiUIji9Dx270NJ9tPYrKODeReoXUQGA8dahPTB4uM= X-Received: by 2002:a6b:e010:: with SMTP id z16mr975916iog.84.1604324691116; Mon, 02 Nov 2020 05:44:51 -0800 (PST) MIME-Version: 1.0 References: <20201028141646.GA75933@rlk> In-Reply-To: <20201028141646.GA75933@rlk> From: Pankaj Gupta Date: Mon, 2 Nov 2020 14:44:39 +0100 Message-ID: Subject: Re: [PATCH v2] mm/list_lru: optimize condition of exiting the loop To: Hui Su Cc: Andrew Morton , gustavo@embeddedor.com, Muchun Song , Vlastimil Babka , LKML , Linux MM Content-Type: text/plain; charset="UTF-8" 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: > In list_lru_walk(), nr_to_walk type is 'unsigned long', > so nr_to_walk won't be '< 0'. > > In list_lru_walk_node(), nr_to_walk type is 'unsigned long', > so *nr_to_walk won't be '< 0' too. > > We can use '!nr_to_walk' instead of 'nr_to_walk <= 0', which > is more precise. > > Signed-off-by: Hui Su > --- > include/linux/list_lru.h | 2 +- > mm/list_lru.c | 4 ++-- > 2 files changed, 3 insertions(+), 3 deletions(-) > > diff --git a/include/linux/list_lru.h b/include/linux/list_lru.h > index 9dcaa3e582c9..b7bc4a2636b9 100644 > --- a/include/linux/list_lru.h > +++ b/include/linux/list_lru.h > @@ -214,7 +214,7 @@ list_lru_walk(struct list_lru *lru, list_lru_walk_cb isolate, > for_each_node_state(nid, N_NORMAL_MEMORY) { > isolated += list_lru_walk_node(lru, nid, isolate, > cb_arg, &nr_to_walk); > - if (nr_to_walk <= 0) > + if (!nr_to_walk) > break; > } > return isolated; > diff --git a/mm/list_lru.c b/mm/list_lru.c > index 5aa6e44bc2ae..35be4de9fd77 100644 > --- a/mm/list_lru.c > +++ b/mm/list_lru.c > @@ -294,7 +294,7 @@ unsigned long list_lru_walk_node(struct list_lru *lru, int nid, > > isolated += list_lru_walk_one(lru, nid, NULL, isolate, cb_arg, > nr_to_walk); > - if (*nr_to_walk > 0 && list_lru_memcg_aware(lru)) { > + if (*nr_to_walk && list_lru_memcg_aware(lru)) { > for_each_memcg_cache_index(memcg_idx) { > struct list_lru_node *nlru = &lru->node[nid]; > > @@ -304,7 +304,7 @@ unsigned long list_lru_walk_node(struct list_lru *lru, int nid, > nr_to_walk); > spin_unlock(&nlru->lock); > > - if (*nr_to_walk <= 0) > + if (!*nr_to_walk) > break; > } > } Acked-by: Pankaj Gupta