Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757949Ab1EKRC7 (ORCPT ); Wed, 11 May 2011 13:02:59 -0400 Received: from ozlabs.org ([203.10.76.45]:38724 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754327Ab1EKRC6 (ORCPT ); Wed, 11 May 2011 13:02:58 -0400 Date: Wed, 11 May 2011 17:25:14 +1000 From: Anton Blanchard To: gregkh@suse.de, nfont@austin.ibm.com Cc: linux-kernel@vger.kernel.org Subject: [PATCH] memory hotplug: Speed up add/remove when blocks are larger than PAGES_PER_SECTION Message-ID: <20110511172514.7e30970d@kryten> X-Mailer: Claws Mail 3.7.8 (GTK+ 2.24.4; i686-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3123 Lines: 98 On ppc64 the minimum memory section for hotplug is 16MB but most recent machines have a memory block size of 256MB. This means memory_block_change_state does 16 separate calls to memory_section_action. This also means we call the notifiers 16 times and the hook in the ehea network driver is quite costly. To offline one 256MB region takes: # time echo offline > /sys/devices/system/memory/memory32/state 7.9s This patch removes the loop and calls online_pages or remove_memory once for the entire region and in doing so makes the logic simpler since we don't have to back out if things fail part way through. The same test to offline one region now takes: # time echo online > /sys/devices/system/memory/memory32/state 0.67s Over 11 times faster. Signed-off-by: Anton Blanchard --- Index: linux-2.6-work/drivers/base/memory.c =================================================================== --- linux-2.6-work.orig/drivers/base/memory.c 2011-05-11 14:04:46.878078801 +1000 +++ linux-2.6-work/drivers/base/memory.c 2011-05-11 14:10:52.134521072 +1000 @@ -228,10 +228,11 @@ int memory_isolate_notify(unsigned long * OK to have direct references to sparsemem variables in here. */ static int -memory_section_action(unsigned long phys_index, unsigned long action) +memory_block_action(unsigned long phys_index, unsigned long action) { int i; unsigned long start_pfn, start_paddr; + unsigned long nr_pages = PAGES_PER_SECTION * sections_per_block; struct page *first_page; int ret; @@ -243,7 +244,7 @@ memory_section_action(unsigned long phys * that way. */ if (action == MEM_ONLINE) { - for (i = 0; i < PAGES_PER_SECTION; i++) { + for (i = 0; i < nr_pages; i++) { if (PageReserved(first_page+i)) continue; @@ -257,12 +258,12 @@ memory_section_action(unsigned long phys switch (action) { case MEM_ONLINE: start_pfn = page_to_pfn(first_page); - ret = online_pages(start_pfn, PAGES_PER_SECTION); + ret = online_pages(start_pfn, nr_pages); break; case MEM_OFFLINE: start_paddr = page_to_pfn(first_page) << PAGE_SHIFT; ret = remove_memory(start_paddr, - PAGES_PER_SECTION << PAGE_SHIFT); + nr_pages << PAGE_SHIFT); break; default: WARN(1, KERN_WARNING "%s(%ld, %ld) unknown action: " @@ -288,20 +289,11 @@ static int memory_block_change_state(str if (to_state == MEM_OFFLINE) mem->state = MEM_GOING_OFFLINE; - for (i = 0; i < sections_per_block; i++) { - ret = memory_section_action(mem->start_section_nr + i, - to_state); - if (ret) - break; - } - - if (ret) { - for (i = 0; i < sections_per_block; i++) - memory_section_action(mem->start_section_nr + i, - from_state_req); + ret = memory_block_action(mem->start_section_nr, to_state); + if (ret) mem->state = from_state_req; - } else + else mem->state = to_state; out: -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/