From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ed1-f72.google.com (mail-ed1-f72.google.com [209.85.208.72]) by kanga.kvack.org (Postfix) with ESMTP id 8E76F6B7E2D for ; Thu, 6 Dec 2018 23:15:32 -0500 (EST) Received: by mail-ed1-f72.google.com with SMTP id i14so1350560edf.17 for ; Thu, 06 Dec 2018 20:15:32 -0800 (PST) Received: from mail-sor-f65.google.com (mail-sor-f65.google.com. [209.85.220.65]) by mx.google.com with SMTPS id m13sor1675139edm.0.2018.12.06.20.15.30 for (Google Transport Security); Thu, 06 Dec 2018 20:15:30 -0800 (PST) Date: Fri, 7 Dec 2018 04:15:28 +0000 From: Wei Yang Subject: Re: [PATCH] mm, kmemleak: Little optimization while scanning Message-ID: <20181207041528.xs4xnw6vpsbu5csx@master> Reply-To: Wei Yang References: <20181206131918.25099-1-osalvador@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181206131918.25099-1-osalvador@suse.de> Sender: owner-linux-mm@kvack.org List-ID: To: Oscar Salvador Cc: akpm@linux-foundation.org, catalin.marinas@arm.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org On Thu, Dec 06, 2018 at 02:19:18PM +0100, Oscar Salvador wrote: >kmemleak_scan() goes through all online nodes and tries >to scan all used pages. >We can do better and use pfn_to_online_page(), so in case we have >CONFIG_MEMORY_HOTPLUG, offlined pages will be skiped automatically. >For boxes where CONFIG_MEMORY_HOTPLUG is not present, pfn_to_online_page() >will fallback to pfn_valid(). > >Another little optimization is to check if the page belongs to the node >we are currently checking, so in case we have nodes interleaved we will >not check the same pfn multiple times. > >I ran some tests: > >Add some memory to node1 and node2 making it interleaved: > >(qemu) object_add memory-backend-ram,id=ram0,size=1G >(qemu) device_add pc-dimm,id=dimm0,memdev=ram0,node=1 >(qemu) object_add memory-backend-ram,id=ram1,size=1G >(qemu) device_add pc-dimm,id=dimm1,memdev=ram1,node=2 >(qemu) object_add memory-backend-ram,id=ram2,size=1G >(qemu) device_add pc-dimm,id=dimm2,memdev=ram2,node=1 > >Then, we offline that memory: > # for i in {32..39} ; do echo "offline" > /sys/devices/system/node/node1/memory$i/state;done > # for i in {48..55} ; do echo "offline" > /sys/devices/system/node/node1/memory$i/state;don > # for i in {40..47} ; do echo "offline" > /sys/devices/system/node/node2/memory$i/state;done > >And we run kmemleak_scan: > > # echo "scan" > /sys/kernel/debug/kmemleak > >before the patch: > >kmemleak: time spend: 41596 us > >after the patch: > >kmemleak: time spend: 34899 us > >Signed-off-by: Oscar Salvador >--- > mm/kmemleak.c | 10 +++++++--- > 1 file changed, 7 insertions(+), 3 deletions(-) > >diff --git a/mm/kmemleak.c b/mm/kmemleak.c >index 877de4fa0720..5ce1e6a46d77 100644 >--- a/mm/kmemleak.c >+++ b/mm/kmemleak.c >@@ -113,6 +113,7 @@ > #include > #include > >+ This one maybe not necessary. > /* > * Kmemleak configuration and common defines. > */ >@@ -1547,11 +1548,14 @@ static void kmemleak_scan(void) > unsigned long pfn; > > for (pfn = start_pfn; pfn < end_pfn; pfn++) { >- struct page *page; >+ struct page *page = pfn_to_online_page(pfn); >+ >+ if (!page) >+ continue; > >- if (!pfn_valid(pfn)) >+ /* only scan pages belonging to this node */ >+ if (page_to_nid(page) != i) > continue; Not farmiliar with this situation. Is this often? >- page = pfn_to_page(pfn); > /* only scan if page is in use */ > if (page_count(page) == 0) > continue; >-- >2.13.7 -- Wei Yang Help you, Help me