Messages in this thread | | | Subject | Re: [PATCH 00/22] Cleanup and optimise the page allocator V7 | From | "Zhang, Yanmin" <> | Date | Tue, 28 Apr 2009 09:59:17 +0800 |
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On Mon, 2009-04-27 at 15:38 +0100, Mel Gorman wrote: > On Mon, Apr 27, 2009 at 03:58:39PM +0800, Zhang, Yanmin wrote: > > On Wed, 2009-04-22 at 14:53 +0100, Mel Gorman wrote: > > > Here is V7 of the cleanup and optimisation of the page allocator and > > > it should be ready for wider testing. Please consider a possibility for > > > merging as a Pass 1 at making the page allocator faster. Other passes will > > > occur later when this one has had a bit of exercise. This patchset is based > > > on mmotm-2009-04-17 and I've tested it successfully on a small number of > > > machines. > > We ran some performance benchmarks against V7 patch on top of 2.6.30-rc3. > > It seems some counters in kernel are incorrect after we run some ffsb (disk I/O benchmark) > > and swap-cp (a simple swap memory testing by cp on tmpfs). Free memory is bigger than > > total memory. > > > > oops. Can you try this patch please? > > ==== CUT HERE ==== > > Properly account for freed pages in free_pages_bulk() and when allocating high-order pages in buffered_rmqueue() > > free_pages_bulk() updates the number of free pages in the zone but it is > assuming that the pages being freed are order-0. While this is currently > always true, it's wrong to assume the order is 0. This patch fixes the > problem. > > buffered_rmqueue() is not updating NR_FREE_PAGES when allocating pages with > __rmqueue(). This means that any high-order allocation will appear to increase > the number of free pages leading to the situation where free pages appears to > exceed available RAM. This patch accounts for those allocated pages properly. > > This is a candidate fix to the patch > page-allocator-update-nr_free_pages-only-as-necessary.patch. It has yet to be > verified as fixing a problem where the free pages count is getting corrupted. > > Signed-off-by: Mel Gorman <mel@csn.ul.ie> > --- > mm/page_alloc.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index 3db5f57..dd69593 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -545,7 +545,7 @@ static void free_pages_bulk(struct zone *zone, int count, > zone_clear_flag(zone, ZONE_ALL_UNRECLAIMABLE); > zone->pages_scanned = 0; > > - __mod_zone_page_state(zone, NR_FREE_PAGES, count); > + __mod_zone_page_state(zone, NR_FREE_PAGES, count << order); > while (count--) { > struct page *page; > > @@ -1151,6 +1151,7 @@ again: > } else { > spin_lock_irqsave(&zone->lock, flags); > page = __rmqueue(zone, order, migratetype); > + __mod_zone_page_state(zone, NR_FREE_PAGES, -(i << order)); Here 'i' should be 1?
> spin_unlock(&zone->lock); > if (!page) > goto failed; I ran a cp kernel source files and swap-cp workload and didn't find bad counter now.
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