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SubjectRe: PERF: performance tests with the split LRU VM in -mm
On Mon, 28 Jul 2008 17:17:28 -0700
Andrew Morton <akpm@linux-foundation.org> wrote:

> /*
> - * Try to keep the active list 2/3 of the size of the cache. And
> - * make sure that refill_inactive is given a decent number of pages.
> - *
> - * The "scan_active + 1" here is important. With pagecache-intensive
> - * workloads the inactive list is huge, and `ratio' evaluates to zero
> - * all the time. Which pins the active list memory. So we add one to

If the active list is so small that nr_active_file >> priority always
evaluates to 0, I suspect it won't hurt at all to keep it around.

After all, we now only scan once the (incrementing) scan number reaches
swap_cluster_max.

> - * `scan_active' just to make sure that the kernel will slowly sift
> - * through the active list.
> + * Add one to `nr_to_scan' just to make sure that the kernel will
> + * slowly sift through the active list.
> */
> - if (zone->nr_active >= 4*(zone->nr_inactive*2 + 1)) {
> - /* Don't scan more than 4 times the inactive list scan size */
> - scan_active = 4*scan_inactive;
>
> (there was some regrettable information loss there).
>
> Is the scenario which that fix addresses no longer possible?

I believe it is possible, but harmless. Maybe even desired.

> On a different topic, I am staring in frustration at
> introduce-__get_user_pages.patch, which says:
>
> New munlock processing need to GUP_FLAGS_IGNORE_VMA_PERMISSIONS.
> because current get_user_pages() can't grab PROT_NONE pages theresore
> it cause PROT_NONE pages can't munlock.
>
> could someone please work out for me which of these patches:
>
> vmscan-move-isolate_lru_page-to-vmscanc.patch
> vmscan-use-an-indexed-array-for-lru-variables.patch
> swap-use-an-array-for-the-lru-pagevecs.patch
> vmscan-free-swap-space-on-swap-in-activation.patch
> define-page_file_cache-function.patch
> vmscan-split-lru-lists-into-anon-file-sets.patch
> vmscan-second-chance-replacement-for-anonymous-pages.patch
> vmscan-fix-pagecache-reclaim-referenced-bit-check.patch
> vmscan-add-newly-swapped-in-pages-to-the-inactive-list.patch
> more-aggressively-use-lumpy-reclaim.patch
> pageflag-helpers-for-configed-out-flags.patch
> unevictable-lru-infrastructure.patch
> unevictable-lru-page-statistics.patch
> ramfs-and-ram-disk-pages-are-unevictable.patch
> shm_locked-pages-are-unevictable.patch
> mlock-mlocked-pages-are-unevictable.patch
> mlock-downgrade-mmap-sem-while-populating-mlocked-regions.patch
> mmap-handle-mlocked-pages-during-map-remap-unmap.patch
>
> that patch fixes?

I'll take a look later. Time to drive home and eat dinner :)

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