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SubjectRe: [RFC PATCH 00/10] Reduce stack usage used by page reclaim V1
On Thu, Apr 15, 2010 at 06:21:33PM +0100, Mel Gorman wrote:
> This is just an RFC to reduce some of the more obvious stack usage in page
> reclaim. It's a bit rushed and I haven't tested this yet but am sending
> it out as there may be others working on similar material and would rather
> avoid overlap. I built on some of Kosaki Motohiro's work.
>

So the first pass seems to have been reasonably well received. Kosaki,
Rik and Johannes, how you do typically test reclaim-related patches for
regressions? My initial sniff-tests look ok with the page leak sorted out
but I typically am not searching for vmscan regressions other than lumpy
reclaim.

> On X86 bit, stack usage figures (generated using a modified bloat-o-meter

This should have been X86-64. The stack shrinkage is less on X86
obviously because of the difference size of pointers and the like.

> that uses checkstack.pl as its input) change in the following ways after
> the series of patches.
>
> add/remove: 2/0 grow/shrink: 0/4 up/down: 804/-1688 (-884)
> function old new delta
> putback_lru_pages - 676 +676
> update_isolated_counts - 128 +128
> do_try_to_free_pages 172 128 -44
> kswapd 1324 1168 -156
> shrink_page_list 1616 1224 -392
> shrink_zone 2320 1224 -1096
>
> There are some growths there but critically they are no longer in the path
> that would call writepages. In the main path, there is about 1K of stack
> lopped off giving a small amount of breathing room.
>
> KOSAKI Motohiro (3):
> vmscan: kill prev_priority completely
> vmscan: move priority variable into scan_control
> vmscan: simplify shrink_inactive_list()
>
> Mel Gorman (7):
> vmscan: Remove useless loop at end of do_try_to_free_pages
> vmscan: Remove unnecessary temporary vars in do_try_to_free_pages
> vmscan: Split shrink_zone to reduce stack usage
> vmscan: Remove unnecessary temporary variables in shrink_zone()
> vmscan: Setup pagevec as late as possible in shrink_inactive_list()
> vmscan: Setup pagevec as late as possible in shrink_page_list()
> vmscan: Update isolated page counters outside of main path in
> shrink_inactive_list()
>
> include/linux/mmzone.h | 15 --
> mm/page_alloc.c | 2 -
> mm/vmscan.c | 447 +++++++++++++++++++++++-------------------------
> mm/vmstat.c | 2 -
> 4 files changed, 210 insertions(+), 256 deletions(-)
>

--
Mel Gorman
Part-time Phd Student Linux Technology Center
University of Limerick IBM Dublin Software Lab


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