From 5409d2cd841cf2c76396470e566500f6505f8d2a Mon Sep 17 00:00:00 2001 From: Anton Blanchard Date: Wed, 11 May 2011 17:25:14 +1000 Subject: [PATCH] memory hotplug: Speed up add/remove when blocks are larger than PAGES_PER_SECTION 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 Signed-off-by: Greg Kroah-Hartman --- drivers/base/memory.c | 24 ++++++++---------------- 1 file changed, 8 insertions(+), 16 deletions(-) diff --git a/drivers/base/memory.c b/drivers/base/memory.c index 3e9aa3d00044..c4c443db7cbf 100644 --- a/drivers/base/memory.c +++ b/drivers/base/memory.c @@ -229,10 +229,11 @@ int memory_isolate_notify(unsigned long val, void *v) * 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; @@ -244,7 +245,7 @@ memory_section_action(unsigned long phys_index, unsigned long action) * 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; @@ -258,12 +259,12 @@ memory_section_action(unsigned long phys_index, unsigned long action) 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: " @@ -289,20 +290,11 @@ static int memory_block_change_state(struct memory_block *mem, 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: