Re: [PATCH]: Cleanup of __alloc_pages

Andrew Morton
2005-11-08T01:54:11Z

"Rohit, Seth" <rohit.seth@intel.com> wrote:
>
> [PATCH]: Clean up of __alloc_pages. Couple of difference from original behavior:
> 1- remove the initial reclaim logic
> 2- GFP_HIGH pages are allowed to go little below watermark sooner.
> 3- Search for free pages unconditionally after direct reclaim.

Would it be possible to break these into three separate patches? The
cleanup part should be #1.

> +/* get_page_from_freeliest loops through all the possible zones
> + * to find out if it can allocate a page. can_try_harder can have following
> + * values:
> + * -1 => No need to check for the watermarks.
> + * 0 => Don't go too low down in deeps below the low watermark (GFP_HIGH)
> + * 1 => Go far below the low watermark. See zone_watermark_ok (RT TASK)
> + *
> + * cpuset check is not performed when the skip_cpuset_chk flag is set.
> + */
> +
> +static struct page *
> +get_page_from_freelist(gfp_t gfp_mask, unsigned int order, struct zone **zones,
> + int can_try_harder, int skip_cpuset_chk)
> +{
> + struct zone *z;
> + struct page *page = NULL;
> + int classzone_idx = zone_idx(zones[0]);
> + int i;
> +
> + /*
> + * Go through the zonelist once, looking for a zone with enough free.
> + * See also cpuset_zone_allowed() comment in kernel/cpuset.c.
> + */
> + for (i = 0; (z = zones[i]) != NULL; i++) {
> + if (!skip_cpuset_chk && (!cpuset_zone_allowed(z, gfp_mask)))

It'd be nice to not have the `skip_cpuset_chk' flag there. a) it gives
Linus conniptions and b) it's a little extra overhead for !CONFIG_CPUSETS
kernels.

> - zone_statistics(zonelist, z);
> + zone_statistics(zonelist, page_zone(page));

Evaluating page_zone() is not completely trivial. Can we avoid the above?