From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx117.postini.com [74.125.245.117]) by kanga.kvack.org (Postfix) with SMTP id 7B5776B006C for ; Wed, 11 Jan 2012 02:25:49 -0500 (EST) Received: by ghrr18 with SMTP id r18so205750ghr.14 for ; Tue, 10 Jan 2012 23:25:48 -0800 (PST) MIME-Version: 1.0 In-Reply-To: <20120109213357.148e7927@annuminas.surriel.com> References: <20120109213156.0ff47ee5@annuminas.surriel.com> <20120109213357.148e7927@annuminas.surriel.com> From: KOSAKI Motohiro Date: Wed, 11 Jan 2012 02:25:26 -0500 Message-ID: Subject: Re: [PATCH -mm 2/2] mm: kswapd carefully invoke compaction Content-Type: text/plain; charset=ISO-8859-1 Sender: owner-linux-mm@kvack.org List-ID: To: Rik van Riel Cc: linux-mm@kvack.org, aarcange@redhat.com, linux-kernel@vger.kernel.org, Mel Gorman , akpm@linux-foundation.org, Johannes Weiner , hughd@google.com > With CONFIG_COMPACTION enabled, kswapd does not try to free > contiguous free pages, even when it is woken for a higher order > request. > > This could be bad for eg. jumbo frame network allocations, which > are done from interrupt context and cannot compact memory themselves. > Higher than before allocation failure rates in the network receive > path have been observed in kernels with compaction enabled. > > Teach kswapd to defragment the memory zones in a node, but only > if required and compaction is not deferred in a zone. > > Signed-off-by: Rik van Riel I agree with we need asynchronous defragmentations feature. But, do we really need to use kswapd for compaction? While kswapd take a compaction work, it can't work to make free memory. -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org