| Message ID | 20200103211657.29237.50194.stgit@localhost.localdomain (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | mm / virtio: Provide support for free page reporting | expand |
On 03.01.20 22:16, Alexander Duyck wrote: > From: Alexander Duyck <alexander.h.duyck@linux.intel.com> > > Rather than walking over the same pages again and again to get to the pages > that have yet to be reported we can save ourselves a significant amount of > time by simply rotating the list so that when we have a full list of > reported pages the head of the list is pointing to the next non-reported > page. Doing this should save us some significant time when processing each > free list. > > This doesn't gain us much in the standard case as all of the non-reported > pages should be near the top of the list already. However in the case of > page shuffling this results in a noticeable improvement. Below are the > will-it-scale page_fault1 w/ THP numbers for 16 tasks with and without > this patch. > > Without: > tasks processes processes_idle threads threads_idle > 16 8093776.25 0.17 5393242.00 38.20 > > With: > tasks processes processes_idle threads threads_idle > 16 8283274.75 0.17 5594261.00 38.15 > > Signed-off-by: Alexander Duyck <alexander.h.duyck@linux.intel.com> > --- > mm/page_reporting.c | 30 ++++++++++++++++++++++-------- > 1 file changed, 22 insertions(+), 8 deletions(-) Just a minor comment while scanning over the patches (will do more review soon), you might want to switch to "mm/page_reporting: " styled subjects for these optimizations.
On Wed, 2020-01-08 at 14:38 +0100, David Hildenbrand wrote: > On 03.01.20 22:16, Alexander Duyck wrote: > > From: Alexander Duyck <alexander.h.duyck@linux.intel.com> > > > > Rather than walking over the same pages again and again to get to the pages > > that have yet to be reported we can save ourselves a significant amount of > > time by simply rotating the list so that when we have a full list of > > reported pages the head of the list is pointing to the next non-reported > > page. Doing this should save us some significant time when processing each > > free list. > > > > This doesn't gain us much in the standard case as all of the non-reported > > pages should be near the top of the list already. However in the case of > > page shuffling this results in a noticeable improvement. Below are the > > will-it-scale page_fault1 w/ THP numbers for 16 tasks with and without > > this patch. > > > > Without: > > tasks processes processes_idle threads threads_idle > > 16 8093776.25 0.17 5393242.00 38.20 > > > > With: > > tasks processes processes_idle threads threads_idle > > 16 8283274.75 0.17 5594261.00 38.15 > > > > Signed-off-by: Alexander Duyck <alexander.h.duyck@linux.intel.com> > > --- > > mm/page_reporting.c | 30 ++++++++++++++++++++++-------- > > 1 file changed, 22 insertions(+), 8 deletions(-) > > Just a minor comment while scanning over the patches (will do more > review soon), you might want to switch to "mm/page_reporting: " styled > subjects for these optimizations. > Okay, I will update if needed for the next version.
diff --git a/mm/page_reporting.c b/mm/page_reporting.c index 1047c6872d4f..6885e74c2367 100644 --- a/mm/page_reporting.c +++ b/mm/page_reporting.c @@ -131,17 +131,27 @@ void __page_reporting_notify(void) if (PageReported(page)) continue; - /* Attempt to pull page from list */ - if (!__isolate_free_page(page, order)) - break; + /* Attempt to pull page from list and place in scatterlist */ + if (*offset) { + if (!__isolate_free_page(page, order)) { + next = page; + break; + } - /* Add page to scatter list */ - --(*offset); - sg_set_page(&sgl[*offset], page, page_len, 0); + /* Add page to scatter list */ + --(*offset); + sg_set_page(&sgl[*offset], page, page_len, 0); - /* If scatterlist isn't full grab more pages */ - if (*offset) continue; + } + + /* + * Make the first non-processed page in the free list + * the new head of the free list before we release the + * zone lock. + */ + if (&page->lru != list && !list_is_first(&page->lru, list)) + list_rotate_to_front(&page->lru, list); /* release lock before waiting on report processing */ spin_unlock_irq(&zone->lock); @@ -169,6 +179,10 @@ void __page_reporting_notify(void) break; } + /* Rotate any leftover pages to the head of the freelist */ + if (&next->lru != list && !list_is_first(&next->lru, list)) + list_rotate_to_front(&next->lru, list); + spin_unlock_irq(&zone->lock); return err;