From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ve0-f178.google.com (mail-ve0-f178.google.com [209.85.128.178]) by kanga.kvack.org (Postfix) with ESMTP id 502776B0035 for ; Thu, 29 May 2014 20:31:43 -0400 (EDT) Received: by mail-ve0-f178.google.com with SMTP id sa20so1338710veb.9 for ; Thu, 29 May 2014 17:31:43 -0700 (PDT) Received: from mail-vc0-x229.google.com (mail-vc0-x229.google.com [2607:f8b0:400c:c03::229]) by mx.google.com with ESMTPS id v10si1909583vew.44.2014.05.29.17.31.42 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Thu, 29 May 2014 17:31:42 -0700 (PDT) Received: by mail-vc0-f169.google.com with SMTP id ij19so1303199vcb.28 for ; Thu, 29 May 2014 17:31:42 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <20140530002021.GM10092@bbox> References: <1401260039-18189-1-git-send-email-minchan@kernel.org> <1401260039-18189-2-git-send-email-minchan@kernel.org> <20140528223142.GO8554@dastard> <20140529013007.GF6677@dastard> <20140529015830.GG6677@dastard> <20140529233638.GJ10092@bbox> <20140530002021.GM10092@bbox> Date: Thu, 29 May 2014 17:31:42 -0700 Message-ID: Subject: Re: [RFC 2/2] x86_64: expand kernel stack to 16K From: Linus Torvalds Content-Type: text/plain; charset=UTF-8 Sender: owner-linux-mm@kvack.org List-ID: To: Minchan Kim Cc: Dave Chinner , Linux Kernel Mailing List , Andrew Morton , linux-mm , "H. Peter Anvin" , Ingo Molnar , Peter Zijlstra , Mel Gorman , Rik van Riel , Johannes Weiner , Hugh Dickins , Rusty Russell , "Michael S. Tsirkin" , Dave Hansen , Steven Rostedt On Thu, May 29, 2014 at 5:20 PM, Minchan Kim wrote: > > I guess this part which avoid swapout in direct reclaim would be key > if this patch were successful. But it could make anon pages rotate back > into inactive's head from tail in direct reclaim path until kswapd can > catch up. And kswapd kswapd can swap out anon pages from tail of inactive > LRU so I suspect it could make side-effect LRU churning. Oh, it could make bad things happen, no question about that. That said, those bad things are what happens to shared mapped pages today, so in that sense it's not new. But large dirty shared mmap's have traditionally been a great way to really hurt out VM, so "it should work as well as shared mapping pages" is definitely not a ringing endorsement! (Of course, *if* we can improve kswapd behavior for both swap-out and shared dirty pages, that would then be a double win, so there is _some_ argument for saying that we should aim to handle both kinds of pages equally). > Anyway, I will queue it into testing machine since Rusty's test is done. You could also try Dave's patch, and _not_ do my mm/vmscan.c part. Linus -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org