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 D76A0C07E9D for ; Mon, 26 Sep 2022 20:18:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230355AbiIZUSE (ORCPT ); Mon, 26 Sep 2022 16:18:04 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:32920 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229781AbiIZUR4 (ORCPT ); Mon, 26 Sep 2022 16:17:56 -0400 Received: from mail-qt1-x832.google.com (mail-qt1-x832.google.com [IPv6:2607:f8b0:4864:20::832]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 973A7A2ABC for ; Mon, 26 Sep 2022 13:17:55 -0700 (PDT) Received: by mail-qt1-x832.google.com with SMTP id cj27so4844768qtb.7 for ; Mon, 26 Sep 2022 13:17:55 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date; bh=Rb6GCSM0rwMC7RphxcUXfyqWbEmBirE3kuWoVyJY+cY=; b=BfqAKVMYHwwYZlynoiuAig5Xy2Kdzo5zoE97xzlkhJtpZlgY6aZRsOLngb0mU81mzx rqMWYXhmK571fJgC9+6FFnapEECf/M1HNnBLUxIAm+CKuO2pl3HpFwUt7FJLx9nvWIck 0N8ksIzX+BcVla6pNEeOM5ZZeUdRClM65JHAOaqUmKkkPvikNjdBMYp/tejc6e/9DQao Nb5H27jYOQUtsn217pCfbyElzmGfKlkcGs/iCCBGV6LLwXbc/4cJQDcB9ZAKu6+HKWNf yzaCfICJ/k3lHghsjVGukSBn7Z0XSi6LDdgGQUfwd9SJMAOtkj/nm4sanptK4u2ajYUm 9yUQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date; bh=Rb6GCSM0rwMC7RphxcUXfyqWbEmBirE3kuWoVyJY+cY=; b=jRgSGRm4QBbhy6LjptTLeo/ROnEM0pRx2iAlaLCkrw/k2dQvkx4JnlCRtKPIEvFih7 Rki1jZoLxQP+5nc2L4A6fBZ+RdGXBh9njroih6RSFBvKOxpTIzZSXJP6a5ammID5+nNy eKhRGagnnUrwKi4qiH4X9dSiXsogUXk7TlIxIIPqDyL2tMuC3GBQvIc7tvnDzyIZT9Z8 dTQQwHHZTZZk8YQf+LzKym67il/1LdggH5on4nJ1BRpiGour7zGlh5tVSNn+9Q6s+UmX qzmlgwZzwPI7j6wJtPebCmlA+ZyZvVV6GTPZdDtU/FUDuGBJID4oXkN3hng925m7gLW9 PXqw== X-Gm-Message-State: ACrzQf1DsdMgI+PnsjuTcTOvrm8PSyK6ZEwWimGV0NX6Aw+4eFFUpn2b uHHS/7FPVyvzviyeMUQJ73Q= X-Google-Smtp-Source: AMsMyM7dXkVsI53zsTHjVazN0L4nTZwfw3Egu112f2V6A2p5syCdTWicJSfE8bpvboXBkQ/IK1mgZQ== X-Received: by 2002:a05:622a:1355:b0:35c:e9e5:6cda with SMTP id w21-20020a05622a135500b0035ce9e56cdamr19721462qtk.91.1664223474553; Mon, 26 Sep 2022 13:17:54 -0700 (PDT) Received: from localhost ([2601:4c1:c100:2270:155c:f237:bceb:6273]) by smtp.gmail.com with ESMTPSA id 20-20020ac85654000000b0035bb8168daesm11618783qtt.57.2022.09.26.13.17.53 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 26 Sep 2022 13:17:54 -0700 (PDT) Date: Mon, 26 Sep 2022 13:17:53 -0700 From: Yury Norov To: "Aneesh Kumar K.V" Cc: linux-mm@kvack.org, akpm@linux-foundation.org, Wei Xu , Huang Ying , Yang Shi , Davidlohr Bueso , Tim C Chen , Michal Hocko , Linux Kernel Mailing List , Hesham Almatary , Dave Hansen , Jonathan Cameron , Alistair Popple , Dan Williams , Johannes Weiner , jvgediya.oss@gmail.com, Bharata B Rao Subject: Re: [PATCH v15 10/10] lib/nodemask: Optimize node_random for nodemask with single NUMA node Message-ID: References: <20220818131042.113280-1-aneesh.kumar@linux.ibm.com> <20220818131042.113280-11-aneesh.kumar@linux.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220818131042.113280-11-aneesh.kumar@linux.ibm.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Aneesh, Please CC maintainers in your recipient list. On Thu, Aug 18, 2022 at 06:40:42PM +0530, Aneesh Kumar K.V wrote: > The most common case for certain node_random usage (demotion nodemask) is with > nodemask weight 1. We can avoid calling get_random_init() in that case and > always return the only node set in the nodemask. Can you move the comment about get_random_int() to the code?. > A simple test as below > before = rdtsc_ordered(); > for (i= 0; i < 100; i++) { > rand = node_random(&nmask); > } > after = rdtsc_ordered(); > > Without fix after - before : 16438 > With fix after - before : 816 > > Reviewed-by: "Huang, Ying" > Signed-off-by: Aneesh Kumar K.V > --- > include/linux/nodemask.h | 15 ++++++++++++--- > 1 file changed, 12 insertions(+), 3 deletions(-) > > diff --git a/include/linux/nodemask.h b/include/linux/nodemask.h > index 4b71a96190a8..ac5b6a371be5 100644 > --- a/include/linux/nodemask.h > +++ b/include/linux/nodemask.h > @@ -504,12 +504,21 @@ static inline int num_node_state(enum node_states state) > static inline int node_random(const nodemask_t *maskp) > { > #if defined(CONFIG_NUMA) && (MAX_NUMNODES > 1) > - int w, bit = NUMA_NO_NODE; > + int w, bit; > > w = nodes_weight(*maskp); > - if (w) > + switch (w) { > + case 0: > + bit = NUMA_NO_NODE; > + break; Why not 'return NUMA_NO_NODE' instead of break thing? > + case 1: > + bit = first_node(*maskp); > + break; > + default: > bit = bitmap_ord_to_pos(maskp->bits, > - get_random_int() % w, MAX_NUMNODES); > + get_random_int() % w, MAX_NUMNODES); Don't fix tabs - it trashes the history. > + break; > + } > return bit; > #else > return 0; > -- > 2.37.2 > >