From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pg0-f70.google.com (mail-pg0-f70.google.com [74.125.83.70]) by kanga.kvack.org (Postfix) with ESMTP id 2287F6B02B4 for ; Mon, 7 Aug 2017 01:42:02 -0400 (EDT) Received: by mail-pg0-f70.google.com with SMTP id 83so88064007pgb.14 for ; Sun, 06 Aug 2017 22:42:02 -0700 (PDT) Received: from mga01.intel.com (mga01.intel.com. [192.55.52.88]) by mx.google.com with ESMTPS id s15si4202877pgs.640.2017.08.06.22.42.00 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sun, 06 Aug 2017 22:42:01 -0700 (PDT) From: "Huang, Ying" Subject: [PATCH -mm -v4 2/5] mm, swap: Fix swap readahead marking Date: Mon, 7 Aug 2017 13:40:35 +0800 Message-Id: <20170807054038.1843-3-ying.huang@intel.com> In-Reply-To: <20170807054038.1843-1-ying.huang@intel.com> References: <20170807054038.1843-1-ying.huang@intel.com> Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Huang Ying , Johannes Weiner , Minchan Kim , Rik van Riel , Shaohua Li , Hugh Dickins , Fengguang Wu , Tim Chen , Dave Hansen From: Huang Ying In the original implementation, it is possible that the existing pages in the swap cache (not newly readahead) could be marked as the readahead pages. This will cause the statistics of swap readahead be wrong and influence the swap readahead algorithm too. This is fixed via marking a page as the readahead page only if it is newly allocated and read from the disk. When testing with linpack, after the fixing the swap readahead hit rate increased from ~66% to ~86%. Signed-off-by: "Huang, Ying" Cc: Johannes Weiner Cc: Minchan Kim Cc: Rik van Riel Cc: Shaohua Li Cc: Hugh Dickins Cc: Fengguang Wu Cc: Tim Chen Cc: Dave Hansen --- mm/swap_state.c | 18 +++++++++++------- 1 file changed, 11 insertions(+), 7 deletions(-) diff --git a/mm/swap_state.c b/mm/swap_state.c index d1bdb31cab13..a901afe9da61 100644 --- a/mm/swap_state.c +++ b/mm/swap_state.c @@ -498,7 +498,7 @@ struct page *swapin_readahead(swp_entry_t entry, gfp_t gfp_mask, unsigned long start_offset, end_offset; unsigned long mask; struct blk_plug plug; - bool do_poll = true; + bool do_poll = true, page_allocated; mask = swapin_nr_pages(offset) - 1; if (!mask) @@ -514,14 +514,18 @@ struct page *swapin_readahead(swp_entry_t entry, gfp_t gfp_mask, blk_start_plug(&plug); for (offset = start_offset; offset <= end_offset ; offset++) { /* Ok, do the async read-ahead now */ - page = read_swap_cache_async(swp_entry(swp_type(entry), offset), - gfp_mask, vma, addr, false); + page = __read_swap_cache_async( + swp_entry(swp_type(entry), offset), + gfp_mask, vma, addr, &page_allocated); if (!page) continue; - if (offset != entry_offset && - likely(!PageTransCompound(page))) { - SetPageReadahead(page); - count_vm_event(SWAP_RA); + if (page_allocated) { + swap_readpage(page, false); + if (offset != entry_offset && + likely(!PageTransCompound(page))) { + SetPageReadahead(page); + count_vm_event(SWAP_RA); + } } put_page(page); } -- 2.11.0 -- 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