Re: [PATCH 07/25] Check in advance if the zonelist needs additional filtering

KOSAKI Motohiro
2009-04-21T06:52:04Z

> Zonelist are filtered based on nodemasks for memory policies normally.
> It can be additionally filters on cpusets if they exist as well as
> noting when zones are full. These simple checks are expensive enough to
> be noticed in profiles. This patch checks in advance if zonelist
> filtering will ever be needed. If not, then the bulk of the checks are
> skipped.
>
> Signed-off-by: Mel Gorman <mel@csn.ul.ie>
> ---
> include/linux/cpuset.h | 2 ++
> mm/page_alloc.c | 37 ++++++++++++++++++++++++++-----------
> 2 files changed, 28 insertions(+), 11 deletions(-)
>
> diff --git a/include/linux/cpuset.h b/include/linux/cpuset.h
> index a5740fc..978e2f1 100644
> --- a/include/linux/cpuset.h
> +++ b/include/linux/cpuset.h
> @@ -97,6 +97,8 @@ static inline void set_mems_allowed(nodemask_t nodemask)
>
> #else /* !CONFIG_CPUSETS */
>
> +#define number_of_cpusets (0)
> +
> static inline int cpuset_init(void) { return 0; }
> static inline void cpuset_init_smp(void) {}
>
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index c8465d0..3613ba4 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -1137,7 +1137,11 @@ failed:
> #define ALLOC_WMARK_HIGH 0x08 /* use pages_high watermark */
> #define ALLOC_HARDER 0x10 /* try to alloc harder */
> #define ALLOC_HIGH 0x20 /* __GFP_HIGH set */
> +#ifdef CONFIG_CPUSETS
> #define ALLOC_CPUSET 0x40 /* check for correct cpuset */
> +#else
> +#define ALLOC_CPUSET 0x00
> +#endif /* CONFIG_CPUSETS */
>
> #ifdef CONFIG_FAIL_PAGE_ALLOC
>
> @@ -1401,6 +1405,7 @@ get_page_from_freelist(gfp_t gfp_mask, nodemask_t *nodemask, unsigned int order,
> nodemask_t *allowednodes = NULL;/* zonelist_cache approximation */
> int zlc_active = 0; /* set if using zonelist_cache */
> int did_zlc_setup = 0; /* just call zlc_setup() one time */
> + int zonelist_filter = 0;
>
> (void)first_zones_zonelist(zonelist, high_zoneidx, nodemask,
> &preferred_zone);
> @@ -1411,6 +1416,10 @@ get_page_from_freelist(gfp_t gfp_mask, nodemask_t *nodemask, unsigned int order,
>
> VM_BUG_ON(order >= MAX_ORDER);
>
> + /* Determine in advance if the zonelist needs filtering */
> + if ((alloc_flags & ALLOC_CPUSET) && unlikely(number_of_cpusets > 1))
> + zonelist_filter = 1;
> +
> zonelist_scan:
> /*
> * Scan zonelist, looking for a zone with enough free.
> @@ -1418,12 +1427,16 @@ zonelist_scan:
> */
> for_each_zone_zonelist_nodemask(zone, z, zonelist,
> high_zoneidx, nodemask) {
> - if (NUMA_BUILD && zlc_active &&
> - !zlc_zone_worth_trying(zonelist, z, allowednodes))
> - continue;
> - if ((alloc_flags & ALLOC_CPUSET) &&
> - !cpuset_zone_allowed_softwall(zone, gfp_mask))
> - goto try_next_zone;
> +
> + /* Ignore the additional zonelist filter checks if possible */
> + if (zonelist_filter) {
> + if (NUMA_BUILD && zlc_active &&
> + !zlc_zone_worth_trying(zonelist, z, allowednodes))
> + continue;
> + if ((alloc_flags & ALLOC_CPUSET) &&
> + !cpuset_zone_allowed_softwall(zone, gfp_mask))
> + goto try_next_zone;
> + }

if number_of_cpusets==1, old code call zlc_zone_worth_trying(). but your one never call.
it seems regression.

>
> if (!(alloc_flags & ALLOC_NO_WATERMARKS)) {
> unsigned long mark;
> @@ -1445,13 +1458,15 @@ zonelist_scan:
> if (page)
> break;
> this_zone_full:
> - if (NUMA_BUILD)
> + if (NUMA_BUILD && zonelist_filter)
> zlc_mark_zone_full(zonelist, z);
> try_next_zone:
> - if (NUMA_BUILD && !did_zlc_setup) {
> - /* we do zlc_setup after the first zone is tried */
> - allowednodes = zlc_setup(zonelist, alloc_flags);
> - zlc_active = 1;
> + if (NUMA_BUILD && zonelist_filter) {
> + if (!did_zlc_setup) {
> + /* do zlc_setup after the first zone is tried */
> + allowednodes = zlc_setup(zonelist, alloc_flags);
> + zlc_active = 1;
> + }
> did_zlc_setup = 1;
> }
> }
> --
> 1.5.6.5
>
> --
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