From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f169.google.com (mail-pf0-f169.google.com [209.85.192.169]) by kanga.kvack.org (Postfix) with ESMTP id B25646B0254 for ; Mon, 7 Mar 2016 20:47:37 -0500 (EST) Received: by mail-pf0-f169.google.com with SMTP id 129so1112495pfw.1 for ; Mon, 07 Mar 2016 17:47:37 -0800 (PST) Received: from mail-pf0-x243.google.com (mail-pf0-x243.google.com. [2607:f8b0:400e:c00::243]) by mx.google.com with ESMTPS id ah10si832181pad.118.2016.03.07.17.47.36 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 07 Mar 2016 17:47:37 -0800 (PST) Received: by mail-pf0-x243.google.com with SMTP id x188so125744pfb.2 for ; Mon, 07 Mar 2016 17:47:36 -0800 (PST) From: Naoya Horiguchi Subject: [PATCH v1] tools/vm/page-types.c: remove memset() in walk_pfn() Date: Tue, 8 Mar 2016 10:47:32 +0900 Message-Id: <1457401652-9226-1-git-send-email-n-horiguchi@ah.jp.nec.com> Sender: owner-linux-mm@kvack.org List-ID: To: linux-mm@kvack.org Cc: Andrew Morton , Vladimir Davydov , Konstantin Khlebnikov , linux-kernel@vger.kernel.org, Naoya Horiguchi , Naoya Horiguchi I found that page-types is very slow and my testing shows many timeout errors. Here's an example with a simple program allocating 1000 thps. $ time ./page-types -p $(pgrep -f test_alloc) ... real 0m17.201s user 0m16.889s sys 0m0.312s $ time ./page-types.patched -p $(pgrep -f test_alloc) ... real 0m0.182s user 0m0.046s sys 0m0.135s Most of time is spent in memset(), which isn't necessary because we check that the return of kpagecgroup_read() is equal to pages and uninitialized memory is never used. So we can drop this memset(). Fixes: 954e95584579 ("tools/vm/page-types.c: add memory cgroup dumping and filtering") Signed-off-by: Naoya Horiguchi --- tools/vm/page-types.c | 2 -- 1 file changed, 2 deletions(-) diff --git v4.5-rc5-mmotm-2016-02-24-16-18/tools/vm/page-types.c v4.5-rc5-mmotm-2016-02-24-16-18_patched/tools/vm/page-types.c index dab61c3..c192baf 100644 --- v4.5-rc5-mmotm-2016-02-24-16-18/tools/vm/page-types.c +++ v4.5-rc5-mmotm-2016-02-24-16-18_patched/tools/vm/page-types.c @@ -633,8 +633,6 @@ static void walk_pfn(unsigned long voffset, unsigned long pages; unsigned long i; - memset(cgi, 0, sizeof cgi); - while (count) { batch = min_t(unsigned long, count, KPAGEFLAGS_BATCH); pages = kpageflags_read(buf, index, batch); -- 2.7.0 -- 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