在 2024/2/20 0:51, Matthew Wilcox 写道:
On Mon, Feb 19, 2024 at 10:17:01PM +0800, lipeifeng@xxxxxxxx wrote:
'commit 6d4675e60135 ("mm: don't be stuck to rmap lock on reclaim path")'
The above patch would avoid reclaim path to stuck rmap lock.
But it would cause some folios in LRU not sorted by aging because
the contended-folios in rmap_walk would be putbacked to the head of LRU
during shrink_folio_list even if the folios are very cold.
The patchset setups new kthread:kshrinkd to reclaim the contended-folio
in rmap_walk when shrink_folio_list, to avoid to break the rules of LRU.
Patch 1/2 didn't make it to my inbox or to lore.
Hi Sir, I had resent to you.
But you should talk
about the real world consequences of this in the cover letter. What do
we observe if this problem happens? How much extra performance will we
gain by applying this patch?
Hi Sir:
Monkey-test in phone with 16G-ram for 300 hours shows that almost one-third
of the contended-pages can be freed successfully next time, putting back
those
folios to LRU's head would break the rules of inative-LRU.
- pgsteal_kshrinkd 262577
- pgscan_kshrinkd 795503
"pgsteal_kshrinkd" means that the amount of those contended-folios which
can be
freed successfully but be putbacked in the head of inactive-LRU, more
than 1GB(262577 folios).
Mobile-phone with 16-ram, the total amount of inactive are around 4.5G,
so that the
contended-folios would break the rules of inactive-LRU.
- nr_inactive_anon 1020953
- nr_inactive_file 204801
Actually, The patchset had been merged in Google kernel/common since
android12-5.10 and android13-5.15, and were taken in more than 100 millions
android-phone devices more than 1.5 years.
But for the reason of GKI, the patches were implemented in the form of
hooks,
the patches merged in google-line as follows:
https://android-review.googlesource.com/c/kernel/common/+/2163904
https://android-review.googlesource.com/c/kernel/common/+/2191343
https://android-review.googlesource.com/c/kernel/common/+/2550490
https://android-review.googlesource.com/c/kernel/common/+/2318311
