From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ed1-f69.google.com (mail-ed1-f69.google.com [209.85.208.69]) by kanga.kvack.org (Postfix) with ESMTP id 0DB7A6B0007 for ; Fri, 19 Oct 2018 20:54:49 -0400 (EDT) Received: by mail-ed1-f69.google.com with SMTP id b34-v6so21350608ede.5 for ; Fri, 19 Oct 2018 17:54:49 -0700 (PDT) Received: from mail-sor-f65.google.com (mail-sor-f65.google.com. [209.85.220.65]) by mx.google.com with SMTPS id w5-v6sor15155787edu.9.2018.10.19.17.54.47 for (Google Transport Security); Fri, 19 Oct 2018 17:54:47 -0700 (PDT) Date: Sat, 20 Oct 2018 00:54:45 +0000 From: Wei Yang Subject: Re: [RFC] put page to pcp->lists[] tail if it is not on the same node Message-ID: <20181020005445.yhoru5dvm3kqxqnm@master> Reply-To: Wei Yang References: <20181019043303.s5axhjfb2v2lzsr3@master> <20181019083818.GQ5819@techsingularity.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181019083818.GQ5819@techsingularity.net> Sender: owner-linux-mm@kvack.org List-ID: To: Mel Gorman Cc: Wei Yang , willy@infradead.org, mhocko@suse.com, linux-mm@kvack.org, akpm@linux-foundation.org On Fri, Oct 19, 2018 at 09:38:18AM +0100, Mel Gorman wrote: >On Fri, Oct 19, 2018 at 04:33:03AM +0000, Wei Yang wrote: >> node >> Reply-To: Wei Yang >> >> Masters, >> >> During the code reading, I pop up this idea. >> >> In case we put some intelegence of NUMA node to pcp->lists[], we may >> get a better performance. >> > >Why? > >> The idea is simple: >> >> Put page on other nodes to the tail of pcp->lists[], because we >> allocate from head and free from tail. >> > >Pages from remote nodes are not placed on local lists. Even in the slab >context, such objects are placed on alien caches which have special >handling. > Hmm... ok, I need to read the code again. >> Since my desktop just has one numa node, I couldn't test the effect. > >I suspect it would eventually cause a crash or at least weirdness as the >page zone ids would not match due to different nodes. > >> Sorry for sending this without a real justification. Hope this will not >> make you uncomfortable. I would be very glad if you suggest some >> verifications that I could do. >> >> Below is my testing patch, look forward your comments. >> > >I commend you trying to understand how the page allocator works but I >suggest you take a step back, pick a workload that is of interest and >profile it to see where hot spots are that may pinpoint where an >improvement can be made. > Thanks for your words. >-- >Mel Gorman >SUSE Labs -- Wei Yang Help you, Help me