Messages in this thread Patch in this message | | | Date | Sun, 05 Sep 2004 15:46:41 +1000 | From | Nick Piggin <> | Subject | [RFC][PATCH 2/3] alloc-order watermarks |
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2/3
Move the watermark checking code into a single function. Extend it to account for the order of the allocation and the number of free pages that could satisfy such a request.
Signed-off-by: Nick Piggin <nickpiggin@yahoo.com.au>
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linux-2.6-npiggin/include/linux/mmzone.h | 2 + linux-2.6-npiggin/mm/page_alloc.c | 57 ++++++++++++++++++++----------- 2 files changed, 40 insertions(+), 19 deletions(-)
diff -puN mm/page_alloc.c~vm-alloc-order-watermarks mm/page_alloc.c --- linux-2.6/mm/page_alloc.c~vm-alloc-order-watermarks 2004-09-05 14:55:46.000000000 +1000 +++ linux-2.6-npiggin/mm/page_alloc.c 2004-09-05 15:10:07.000000000 +1000 @@ -676,6 +676,36 @@ buffered_rmqueue(struct zone *zone, int } /* + * Return the number of pages available for order 'order' allocations. + */ +int zone_watermark_ok(struct zone *z, int order, unsigned long mark, + int alloc_type, int can_try_harder, int gfp_high) +{ + unsigned long min = mark, free_pages = z->free_pages; + int o; + + if (gfp_high) + min -= min / 2; + if (can_try_harder) + min -= min / 4; + min += z->protection[alloc_type]; + + if (free_pages < min) + return 0; + for (o = 0; o < order; o++) { + /* At the next order, this order's pages become unavailable */ + free_pages -= z->free_area[order].nr_free << o; + + /* Require fewer higher order pages to be free */ + min >>= 1; + + if (free_pages < min + (1 << order) - 1) + return 0; + } + return 1; +} + +/* * This is the 'heart' of the zoned buddy allocator. * * Herein lies the mysterious "incremental min". That's the @@ -696,7 +726,6 @@ __alloc_pages(unsigned int gfp_mask, uns struct zonelist *zonelist) { const int wait = gfp_mask & __GFP_WAIT; - unsigned long min; struct zone **zones, *z; struct page *page; struct reclaim_state reclaim_state; @@ -732,9 +761,9 @@ __alloc_pages(unsigned int gfp_mask, uns /* Go through the zonelist once, looking for a zone with enough free */ for (i = 0; (z = zones[i]) != NULL; i++) { - min = z->pages_low + (1<<order) + z->protection[alloc_type]; - if (z->free_pages < min) + if (!zone_watermark_ok(z, order, z->pages_low, + alloc_type, 0, 0)) continue; if (!cpuset_zone_allowed(z)) @@ -753,14 +782,9 @@ __alloc_pages(unsigned int gfp_mask, uns * coming from realtime tasks to go deeper into reserves */ for (i = 0; (z = zones[i]) != NULL; i++) { - min = z->pages_min; - if (gfp_mask & __GFP_HIGH) - min /= 2; - if (can_try_harder) - min -= min / 4; - min += (1<<order) + z->protection[alloc_type]; - - if (z->free_pages < min) + if (!zone_watermark_ok(z, order, z->pages_min, + alloc_type, can_try_harder, + gfp_mask & __GFP_HIGH)) continue; if (!cpuset_zone_allowed(z)) @@ -801,14 +825,9 @@ rebalance: /* go through the zonelist yet one more time */ for (i = 0; (z = zones[i]) != NULL; i++) { - min = z->pages_min; - if (gfp_mask & __GFP_HIGH) - min /= 2; - if (can_try_harder) - min -= min / 4; - min += (1<<order) + z->protection[alloc_type]; - - if (z->free_pages < min) + if (!zone_watermark_ok(z, order, z->pages_min, + alloc_type, can_try_harder, + gfp_mask & __GFP_HIGH)) continue; if (!cpuset_zone_allowed(z)) diff -puN include/linux/mmzone.h~vm-alloc-order-watermarks include/linux/mmzone.h --- linux-2.6/include/linux/mmzone.h~vm-alloc-order-watermarks 2004-09-05 14:55:46.000000000 +1000 +++ linux-2.6-npiggin/include/linux/mmzone.h 2004-09-05 15:10:07.000000000 +1000 @@ -279,6 +279,8 @@ void get_zone_counts(unsigned long *acti unsigned long *free); void build_all_zonelists(void); void wakeup_kswapd(struct zone *zone); +int zone_watermark_ok(struct zone *z, int order, unsigned long mark, + int alloc_type, int can_try_harder, int gfp_high); /* * zone_idx() returns 0 for the ZONE_DMA zone, 1 for the ZONE_NORMAL zone, etc. _
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