在 2022/8/15 上午11:20, Chuyi Zhou 写道:
在 2022/8/15 上午9:24, Andrew Morton 写道:
On Tue, 19 Jul 2022 09:28:54 +0100 Mel Gorman
<mgorman@xxxxxxxxxxxxxxxxxxx> wrote:
The return block indeed may not be aligned. It could simply be a
restart. The changelog could still do with a little clarification but
your patch is still fine.
I'm not seeing a v4 so I merged the v3. It would be great if someone
could please send along an updated changelog?
Hi, Morton, Here is the updated changelog:
The fast_find_migrateblock could return a block aligned with
pageblock_nr_pages. When we successfully find a block, we use
pageblock_start_pfn(free_pfn) to get the first pfn of the pageblock,
the block will be set skip through *set_pageblock_skip*, normally
the value get from pageblock_start_pfn should be aligned with
*pageblock_nr_pages*. Then the *first pfn* will be passed to
isolate_migratepages_block, the whole pageblock will be skipped
due to the branch
if (!valid_page && IS_ALIGNED(low_pfn, pageblock_nr_pages)), because
!valid_page will be true for the first pageblock, and the low_pfn could
be aligned with pageblock_nr_pages as mentioned above. Eventually we
will goto isolate_abort and isolate nothing. That cause
fast_find_migrateblock useless.
In this Patch, when we find a suitable pageblock in fast_find_
migrateblock, we do noting but let isolate_migratepages_block
to set skip to the pageblock after scan it. Normally,
we would isolate some pages from the fast-find block.
I use mmtest/thpscale-madvhugepage test it. Here is the result:
baseline patch
Amean fault-both-1 1331.66 ( 0.00%) 1261.04 * 5.30%*
Amean fault-both-3 1383.95 ( 0.00%) 1191.69 * 13.89%*
Amean fault-both-5 1568.13 ( 0.00%) 1445.20 * 7.84%*
Amean fault-both-7 1819.62 ( 0.00%) 1555.13 * 14.54%*
Amean fault-both-12 1106.96 ( 0.00%) 1149.43 * -3.84%*
Amean fault-both-18 2196.93 ( 0.00%) 1875.77 * 14.62%*
Amean fault-both-24 2642.69 ( 0.00%) 2671.21 * -1.08%*
Amean fault-both-30 2901.89 ( 0.00%) 2857.32 * 1.54%*
Amean fault-both-32 3747.00 ( 0.00%) 3479.23 * 7.15%*
Fixes: 70b44595eafe9 ("mm, compaction: use free lists to quickly locate
a migration source")
Signed-off-by: zhouchuyi <zhouchuyi@xxxxxxxxxxxxx>
=======================================================================
Mel think it could be possible that the fast_find_migrateblock can return
a pageblock not aligned pageblock_nr_pages. In that case,
isolate_migratepages_block would not set skip flag.
I want to fix this problem in v4.
