Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751577AbbGXOW1 (ORCPT ); Fri, 24 Jul 2015 10:22:27 -0400 Received: from mx1.redhat.com ([209.132.183.28]:55247 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750734AbbGXOWZ (ORCPT ); Fri, 24 Jul 2015 10:22:25 -0400 Message-ID: <55B24A1D.1030400@redhat.com> Date: Fri, 24 Jul 2015 10:22:21 -0400 From: Rik van Riel User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.3.0 MIME-Version: 1.0 To: Vlastimil Babka , linux-mm@kvack.org CC: linux-kernel@vger.kernel.org, Andrew Morton , Hugh Dickins , Andrea Arcangeli , "Kirill A. Shutemov" , Mel Gorman , David Rientjes , Joonsoo Kim Subject: Re: [RFC v2 0/4] Outsourcing compaction for THP allocations to kcompactd References: <1435826795-13777-1-git-send-email-vbabka@suse.cz> In-Reply-To: <1435826795-13777-1-git-send-email-vbabka@suse.cz> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1265 Lines: 28 On 07/02/2015 04:46 AM, Vlastimil Babka wrote: > This RFC series is another evolution of the attempt to deal with THP > allocations latencies. Please see the motivation in the previous version [1] > > The main difference here is that I've bitten the bullet and implemented > per-node kcompactd kthreads - see Patch 1 for the details of why and how. > Trying to fit everything into khugepaged was getting too clumsy, and kcompactd > could have more benefits, see e.g. the ideas here [2]. Not everything is > implemented yet, though, I would welcome some feedback first. This leads to a few questions, one of which has an obvious answer. 1) Why should this functionality not be folded into kswapd? (because kswapd can get stuck on IO for long periods of time) 2) Given that kswapd can get stuck on IO for long periods of time, are there other tasks we may want to break out of kswapd, in order to reduce page reclaim latencies for things like network allocations? (freeing clean inactive pages?) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/