From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-lf0-f72.google.com (mail-lf0-f72.google.com [209.85.215.72]) by kanga.kvack.org (Postfix) with ESMTP id CFCC36B0069 for ; Wed, 12 Oct 2016 10:51:59 -0400 (EDT) Received: by mail-lf0-f72.google.com with SMTP id i187so28903368lfe.4 for ; Wed, 12 Oct 2016 07:51:59 -0700 (PDT) Received: from mx2.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id j130si4997014lfe.268.2016.10.12.07.51.57 for (version=TLS1 cipher=AES128-SHA bits=128/128); Wed, 12 Oct 2016 07:51:58 -0700 (PDT) Subject: Re: [RFC 4/4] mm, page_alloc: disallow migratetype fallback in fastpath References: <20160928014148.GA21007@cmpxchg.org> <20160929210548.26196-1-vbabka@suse.cz> <20160929210548.26196-5-vbabka@suse.cz> From: Vlastimil Babka Message-ID: Date: Wed, 12 Oct 2016 16:51:48 +0200 MIME-Version: 1.0 In-Reply-To: <20160929210548.26196-5-vbabka@suse.cz> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Johannes Weiner Cc: Mel Gorman , Joonsoo Kim , linux-kernel@vger.kernel.org, linux-mm@kvack.org, kernel-team@fb.com On 09/29/2016 11:05 PM, Vlastimil Babka wrote: > The previous patch has adjusted async compaction so that it helps against > longterm fragmentation when compacting for a non-MOVABLE high-order allocation. > The goal of this patch is to force such allocations go through compaction > once before being allowed to fallback to a pageblock of different migratetype > (e.g. MOVABLE). In contexts where compaction is not allowed (and for order-0 > allocations), this delayed fallback possibility can still help by trying a > different zone where fallback might not be needed and potentially waking up > kswapd earlier. > > Not-yet-signed-off-by: Vlastimil Babka I forgot that compaction itself also needs to be told to not allow fallback, otherwise it finishes with COMPACT_SUCCESS without actually doing anything...