From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx195.postini.com [74.125.245.195]) by kanga.kvack.org (Postfix) with SMTP id 5415A6B0006 for ; Mon, 1 Apr 2013 10:24:20 -0400 (EDT) Message-ID: <5159988E.60104@redhat.com> Date: Mon, 01 Apr 2013 10:24:14 -0400 From: Rik van Riel MIME-Version: 1.0 Subject: Re: [patch]THP: add split tail pages to shrink page list in page reclaim References: <20130401132605.GA2996@kernel.org> In-Reply-To: <20130401132605.GA2996@kernel.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Shaohua Li Cc: linux-mm@kvack.org, akpm@linux-foundation.org, hughd@google.com, aarcange@redhat.com, minchan@kernel.org On 04/01/2013 09:26 AM, Shaohua Li wrote: > In page reclaim, huge page is split. split_huge_page() adds tail pages to LRU > list. Since we are reclaiming a huge page, it's better we reclaim all subpages > of the huge page instead of just the head page. This patch adds split tail > pages to shrink page list so the tail pages can be reclaimed soon. > > Before this patch, run a swap workload: > thp_fault_alloc 3492 > thp_fault_fallback 608 > thp_collapse_alloc 6 > thp_collapse_alloc_failed 0 > thp_split 916 > > With this patch: > thp_fault_alloc 4085 > thp_fault_fallback 16 > thp_collapse_alloc 90 > thp_collapse_alloc_failed 0 > thp_split 1272 > > fallback allocation is reduced a lot. > > Signed-off-by: Shaohua Li I'm not entirely happy that lru_add_page_tail can now add a page to list that is not an LRU list, but the patch does do the right thing policy wise, and I am not sure how to do it better... Acked-by: Rik van Riel -- All rights reversed -- 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