-
Notifications
You must be signed in to change notification settings - Fork 53.5k
Commit
This commit does not belong to any branch on this repository, and may belong to a fork outside of the repository.
mm/hugetlb_vmemmap: batch HVO work when demoting
Batch the HVO work, including de-HVO of the source and HVO of the destination hugeTLB folios, to speed up demotion. After commit bd22553 ("mm/hugetlb_vmemmap: fix race with speculative PFN walkers"), each request of HVO or de-HVO, batched or not, invokes synchronize_rcu() once. For example, when not batched, demoting one 1GB hugeTLB folio to 512 2MB hugeTLB folios invokes synchronize_rcu() 513 times (1 de-HVO plus 512 HVO requests), whereas when batched, only twice (1 de-HVO plus 1 HVO request). And the performance difference between the two cases is significant, e.g., echo 2048kB >/sys/kernel/mm/hugepages/hugepages-1048576kB/demote_size time echo 100 >/sys/kernel/mm/hugepages/hugepages-1048576kB/demote Before this patch: real 8m58.158s user 0m0.009s sys 0m5.900s After this patch: real 0m0.900s user 0m0.000s sys 0m0.851s Note that this patch changes the behavior of the `demote` interface when de-HVO fails. Before, the interface aborts immediately upon failure; now, it tries to finish an entire batch, meaning it can make extra progress if the rest of the batch contains folios that do not need to de-HVO. Link: https://lkml.kernel.org/r/[email protected] Fixes: bd22553 ("mm/hugetlb_vmemmap: fix race with speculative PFN walkers") Signed-off-by: Yu Zhao <[email protected]> Reviewed-by: Muchun Song <[email protected]> Cc: <[email protected]> Signed-off-by: Andrew Morton <[email protected]>
- Loading branch information
1 parent
67b9a35
commit c0f398c
Showing
1 changed file
with
92 additions
and
64 deletions.
There are no files selected for viewing
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters