Re: [PATCH 19/21] swap_prefetch: Conversion of nr_unstable to ZVC

Con Kolivas
2006-06-13T00:01:05Z

On Tuesday 13 June 2006 09:48, Christoph Lameter wrote:
> On Tue, 13 Jun 2006, Con Kolivas wrote:
> > Nack. You're changing some other code unintentionally.
>
> Is this okay?

Not quite.

Remove the test_pagestate variable entirely and leave the check something
like:

if (!(sp_stat.prefetched_pages % SWAP_CLUSTER_MAX) &&
above_background_load())
goto out;

Thanks

>
> Subject: swap_prefetch: conversion of nr_unstable to per zone counter
> From: Christoph Lameter <clameter@sgi.com>
>
> The determination of the vm state is now not that expensive
> anymore after we remove the use of the page state.
> Remove the logic to avoid the expensive checks.
>
> Signed-off-by: Christoph Lameter <clameter@sgi.com>
> Signed-off-by: Andrew Morton <akpm@osdl.org>
>
> Index: linux-2.6.17-rc6-cl/mm/swap_prefetch.c
> ===================================================================
> --- linux-2.6.17-rc6-cl.orig/mm/swap_prefetch.c 2006-06-12
> 13:37:47.283159568 -0700 +++
> linux-2.6.17-rc6-cl/mm/swap_prefetch.c 2006-06-12 16:46:48.504626417 -0700
> @@ -357,7 +357,6 @@ static int prefetch_suitable(void)
> */
> for_each_node_mask(node, sp_stat.prefetch_nodes) {
> struct node_stats *ns = &sp_stat.node[node];
> - struct page_state ps;
>
> /*
> * We check to see that pages are not being allocated
> @@ -375,11 +374,6 @@ static int prefetch_suitable(void)
> } else
> ns->last_free = ns->current_free;
>
> - if (!test_pagestate)
> - continue;
> -
> - get_page_state_node(&ps, node);
> -
> /* We shouldn't prefetch when we are doing writeback */
> if (node_page_state(node, NR_WRITEBACK)) {
> node_clear(node, sp_stat.prefetch_nodes);
> @@ -394,7 +388,8 @@ static int prefetch_suitable(void)
> node_page_state(node, NR_ANON) +
> node_page_state(node, NR_SLAB) +
> node_page_state(node, NR_DIRTY) +
> - ps.nr_unstable + total_swapcache_pages;
> + node_page_state(node, NR_UNSTABLE) +
> + total_swapcache_pages;
> if (limit > ns->prefetch_watermark) {
> node_clear(node, sp_stat.prefetch_nodes);
> continue;

--
-ck