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SubjectRe: [PATCH 1/3] mm,vmscan: Convert lumpy_mode into a bitmask
Date
> Currently lumpy_mode is an enum and determines if lumpy reclaim is off,
> syncronous or asyncronous. In preparation for using compaction instead of
> lumpy reclaim, this patch converts the flags into a bitmap.
>
> Signed-off-by: Mel Gorman <mel@csn.ul.ie>
> ---
> include/trace/events/vmscan.h | 6 +++---
> mm/vmscan.c | 37 +++++++++++++++++++------------------
> 2 files changed, 22 insertions(+), 21 deletions(-)
>
> diff --git a/include/trace/events/vmscan.h b/include/trace/events/vmscan.h
> index c255fcc..be76429 100644
> --- a/include/trace/events/vmscan.h
> +++ b/include/trace/events/vmscan.h
> @@ -25,13 +25,13 @@
>
> #define trace_reclaim_flags(page, sync) ( \
> (page_is_file_cache(page) ? RECLAIM_WB_FILE : RECLAIM_WB_ANON) | \
> - (sync == LUMPY_MODE_SYNC ? RECLAIM_WB_SYNC : RECLAIM_WB_ASYNC) \
> + (sync & LUMPY_MODE_SYNC ? RECLAIM_WB_SYNC : RECLAIM_WB_ASYNC) \
> )
>
> #define trace_shrink_flags(file, sync) ( \
> - (sync == LUMPY_MODE_SYNC ? RECLAIM_WB_MIXED : \
> + (sync & LUMPY_MODE_SYNC ? RECLAIM_WB_MIXED : \
> (file ? RECLAIM_WB_FILE : RECLAIM_WB_ANON)) | \
> - (sync == LUMPY_MODE_SYNC ? RECLAIM_WB_SYNC : RECLAIM_WB_ASYNC) \
> + (sync & LUMPY_MODE_SYNC ? RECLAIM_WB_SYNC : RECLAIM_WB_ASYNC) \
> )
>
> TRACE_EVENT(mm_vmscan_kswapd_sleep,
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index b8a6fdc..ffa438e 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -51,11 +51,11 @@
> #define CREATE_TRACE_POINTS
> #include <trace/events/vmscan.h>
>
> -enum lumpy_mode {
> - LUMPY_MODE_NONE,
> - LUMPY_MODE_ASYNC,
> - LUMPY_MODE_SYNC,
> -};
> +typedef unsigned __bitwise__ lumpy_mode;
> +#define LUMPY_MODE_SINGLE ((__force lumpy_mode)0x01u)
> +#define LUMPY_MODE_ASYNC ((__force lumpy_mode)0x02u)
> +#define LUMPY_MODE_SYNC ((__force lumpy_mode)0x04u)
> +#define LUMPY_MODE_CONTIGRECLAIM ((__force lumpy_mode)0x08u)

Please write a comment of description of each bit meaning.


>
> struct scan_control {
> /* Incremented by the number of inactive pages that were scanned */
> @@ -88,7 +88,7 @@ struct scan_control {
> * Intend to reclaim enough continuous memory rather than reclaim
> * enough amount of memory. i.e, mode for high order allocation.
> */
> - enum lumpy_mode lumpy_reclaim_mode;
> + lumpy_mode lumpy_reclaim_mode;
>
> /* Which cgroup do we reclaim from */
> struct mem_cgroup *mem_cgroup;
> @@ -274,13 +274,13 @@ unsigned long shrink_slab(unsigned long scanned, gfp_t gfp_mask,
> static void set_lumpy_reclaim_mode(int priority, struct scan_control *sc,
> bool sync)
> {
> - enum lumpy_mode mode = sync ? LUMPY_MODE_SYNC : LUMPY_MODE_ASYNC;
> + lumpy_mode mode = sync ? LUMPY_MODE_SYNC : LUMPY_MODE_ASYNC;
>
> /*
> * Some reclaim have alredy been failed. No worth to try synchronous
> * lumpy reclaim.
> */
> - if (sync && sc->lumpy_reclaim_mode == LUMPY_MODE_NONE)
> + if (sync && sc->lumpy_reclaim_mode & LUMPY_MODE_SINGLE)
> return;

Probaby, we can remove LUMPY_MODE_SINGLE entirely. and this line can be
change to

if (sync && !(sc->lumpy_reclaim_mode & LUMPY_MODE_CONTIGRECLAIM))


btw, LUMPY_MODE_ASYNC can be removed too.


>
> /*
> @@ -288,17 +288,18 @@ static void set_lumpy_reclaim_mode(int priority, struct scan_control *sc,
> * trouble getting a small set of contiguous pages, we
> * will reclaim both active and inactive pages.
> */
> + sc->lumpy_reclaim_mode = LUMPY_MODE_CONTIGRECLAIM;
> if (sc->order > PAGE_ALLOC_COSTLY_ORDER)
> - sc->lumpy_reclaim_mode = mode;
> + sc->lumpy_reclaim_mode |= mode;
> else if (sc->order && priority < DEF_PRIORITY - 2)
> - sc->lumpy_reclaim_mode = mode;
> + sc->lumpy_reclaim_mode |= mode;
> else
> - sc->lumpy_reclaim_mode = LUMPY_MODE_NONE;
> + sc->lumpy_reclaim_mode = LUMPY_MODE_SINGLE | LUMPY_MODE_ASYNC;
> }
>
> static void disable_lumpy_reclaim_mode(struct scan_control *sc)
> {
> - sc->lumpy_reclaim_mode = LUMPY_MODE_NONE;
> + sc->lumpy_reclaim_mode = LUMPY_MODE_SINGLE | LUMPY_MODE_ASYNC;
> }
>
> static inline int is_page_cache_freeable(struct page *page)
> @@ -429,7 +430,7 @@ static pageout_t pageout(struct page *page, struct address_space *mapping,
> * first attempt to free a range of pages fails.
> */
> if (PageWriteback(page) &&
> - sc->lumpy_reclaim_mode == LUMPY_MODE_SYNC)
> + (sc->lumpy_reclaim_mode & LUMPY_MODE_SYNC))
> wait_on_page_writeback(page);
>
> if (!PageWriteback(page)) {
> @@ -615,7 +616,7 @@ static enum page_references page_check_references(struct page *page,
> referenced_page = TestClearPageReferenced(page);
>
> /* Lumpy reclaim - ignore references */
> - if (sc->lumpy_reclaim_mode != LUMPY_MODE_NONE)
> + if (sc->lumpy_reclaim_mode & LUMPY_MODE_CONTIGRECLAIM)
> return PAGEREF_RECLAIM;
>
> /*
> @@ -732,7 +733,7 @@ static unsigned long shrink_page_list(struct list_head *page_list,
> * for any page for which writeback has already
> * started.
> */
> - if (sc->lumpy_reclaim_mode == LUMPY_MODE_SYNC &&
> + if ((sc->lumpy_reclaim_mode & LUMPY_MODE_SYNC) &&
> may_enter_fs)
> wait_on_page_writeback(page);
> else {
> @@ -1317,7 +1318,7 @@ static inline bool should_reclaim_stall(unsigned long nr_taken,
> return false;
>
> /* Only stall on lumpy reclaim */
> - if (sc->lumpy_reclaim_mode == LUMPY_MODE_NONE)
> + if (sc->lumpy_reclaim_mode & LUMPY_MODE_SINGLE)
> return false;
>
> /* If we have relaimed everything on the isolated list, no stall */
> @@ -1368,7 +1369,7 @@ shrink_inactive_list(unsigned long nr_to_scan, struct zone *zone,
> if (scanning_global_lru(sc)) {
> nr_taken = isolate_pages_global(nr_to_scan,
> &page_list, &nr_scanned, sc->order,
> - sc->lumpy_reclaim_mode == LUMPY_MODE_NONE ?
> + sc->lumpy_reclaim_mode & LUMPY_MODE_SINGLE ?
> ISOLATE_INACTIVE : ISOLATE_BOTH,
> zone, 0, file);
> zone->pages_scanned += nr_scanned;
> @@ -1381,7 +1382,7 @@ shrink_inactive_list(unsigned long nr_to_scan, struct zone *zone,
> } else {
> nr_taken = mem_cgroup_isolate_pages(nr_to_scan,
> &page_list, &nr_scanned, sc->order,
> - sc->lumpy_reclaim_mode == LUMPY_MODE_NONE ?
> + sc->lumpy_reclaim_mode & LUMPY_MODE_SINGLE ?
> ISOLATE_INACTIVE : ISOLATE_BOTH,
> zone, sc->mem_cgroup,
> 0, file);
> --
> 1.7.1
>





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