Synchronous Lumpy Reclaim V3
Get series with b4
b4 am exportbomb.1186077923@pinkyVersions newest first
- v1 Latest2 patches 2 repliesIn review
Patches in v1 No applies recorded yet
| # | Subject and files | Size | Replies | Applied |
|---|---|---|---|---|
| 1/2 | ensure we count pages transitioning inactive via clear_active_flagsmm/ | +1 | 0 replies | |
| 2/2 | wait for page writeback when directly reclaiming contiguous areasmm/ | +52 | 2 replies |
Reviews trailers per patch
1 of 2 patches has a Reviewed-by or Acked-by of their own; the series has one for all of them.
| Patch | Mel Gorman | Peter Zijlstra |
|---|---|---|
| Series | A-b | |
| 1/2 | A-b | |
| 2/2 |
Trailers given in replies are filled; those carried in the patches from earlier versions are outlined with dashes.
Cover letter [PATCH 0/2] Synchronous Lumpy Reclaim V3
[This is a re-spin based on feedback from akpm.]
As pointed out by Mel when reclaim is applied at higher orders a significant amount of IO may be started. As this takes finite time to drain reclaim will consider more areas than ultimatly needed to satisfy the request. This leads to more reclaim than strictly required and reduced success rates.
I was able to confirm Mel's test results on systems locally. These show that even under light load the success rates drop off far more than expected. Testing with a modified version of his patch (which follows) I was able to allocate almost all of ZONE_MOVABLE with a near idle system. I ran 5 test passes sequentially following system boot (the system has 29 hugepages in ZONE_MOVABLE):
2.6.23-rc1 11 8 6 7 7
sync_lumpy 28 28 29 29 26
These show that although hugely better than the near 0% success normally expected we can only allocate about a 1/4 of the zone. Using synchronous reclaim for these allocations we get close to 100% as expected.
I have also run our standard high order tests and these show no regressions in allocation success rates at rest, and some significant improvements under load.
Following this email are two patches, both should be considered as bug fixes to lumpy reclaim for 2.6.23:
ensure-we-count-pages-transitioning-inactive-via-clear_active_flags:
this a bug fix for Lumpy Reclaim fixing up a bug in VM Event accounting when it marks pages inactive, and
Wait-for-page-writeback-when-directly-reclaiming-contiguous-areas:
updates reclaim making direct reclaim synchronous when applied at orders above PAGE_ALLOC_COSTLY_ORDER.
Patches against 2.6.23-rc1. Andrew please consider for -mm and for pushing to mainline.
-apw