2006-05-18 05:59:08

by Con Kolivas

Subject: [PATCH] mm: swap prefetch fix lowmem reserve calc

When examining the free limits in swap_prefetch we should ensure the largest
lowmem_reserve for each zone is free.

Signed-off-by: Con Kolivas <[email protected]>

---
mm/swap_prefetch.c | 14 +++++++++++++-
1 files changed, 13 insertions(+), 1 deletion(-)

Index: linux-2.6.17-rc4-mm1/mm/swap_prefetch.c
===================================================================
--- linux-2.6.17-rc4-mm1.orig/mm/swap_prefetch.c 2006-05-18 15:48:22.000000000 +1000
+++ linux-2.6.17-rc4-mm1/mm/swap_prefetch.c 2006-05-18 15:52:42.000000000 +1000
@@ -258,6 +258,18 @@ static void clear_current_prefetch_free(
}
}

+static inline unsigned long largest_lowmem_reserve(struct zone *z)
+{
+ unsigned long ret = 0;
+ unsigned int idx = zone_idx(z);
+
+ while (!is_highmem_idx(idx)) {
+ idx++;
+ ret = max(ret, z->lowmem_reserve[idx]);
+ }
+ return ret;
+}
+
/*
* This updates the high and low watermarks of amount of free ram in each
* node used to start and stop prefetching. We prefetch from pages_high * 4
@@ -276,7 +288,7 @@ static void examine_free_limits(void)

ns = &sp_stat.node[z->zone_pgdat->node_id];
idx = zone_idx(z);
- ns->lowfree[idx] = z->pages_high * 3 + z->lowmem_reserve[idx];
+ ns->lowfree[idx] = z->pages_high * 3 + largest_lowmem_reserve(z);
ns->highfree[idx] = ns->lowfree[idx] + z->pages_high;

if (z->free_pages > ns->highfree[idx]) {

--
-ck

2006-05-18 07:18:36

by Nick Piggin

Subject: Re: [PATCH] mm: swap prefetch fix lowmem reserve calc

Con Kolivas wrote:
> When examining the free limits in swap_prefetch we should ensure the largest
> lowmem_reserve for each zone is free.
>
> Signed-off-by: Con Kolivas <[email protected]>
>
> ---
> mm/swap_prefetch.c | 14 +++++++++++++-
> 1 files changed, 13 insertions(+), 1 deletion(-)
>
> Index: linux-2.6.17-rc4-mm1/mm/swap_prefetch.c
> ===================================================================
> --- linux-2.6.17-rc4-mm1.orig/mm/swap_prefetch.c 2006-05-18 15:48:22.000000000 +1000
> +++ linux-2.6.17-rc4-mm1/mm/swap_prefetch.c 2006-05-18 15:52:42.000000000 +1000
> @@ -258,6 +258,18 @@ static void clear_current_prefetch_free(
> }
> }
>
> +static inline unsigned long largest_lowmem_reserve(struct zone *z)
> +{
> + unsigned long ret = 0;
> + unsigned int idx = zone_idx(z);
> +
> + while (!is_highmem_idx(idx)) {
> + idx++;
> + ret = max(ret, z->lowmem_reserve[idx]);
> + }
> + return ret;
> +}
> +
> /*
> * This updates the high and low watermarks of amount of free ram in each
> * node used to start and stop prefetching. We prefetch from pages_high * 4
> @@ -276,7 +288,7 @@ static void examine_free_limits(void)
>
> ns = &sp_stat.node[z->zone_pgdat->node_id];
> idx = zone_idx(z);
> - ns->lowfree[idx] = z->pages_high * 3 + z->lowmem_reserve[idx];
> + ns->lowfree[idx] = z->pages_high * 3 + largest_lowmem_reserve(z);
> ns->highfree[idx] = ns->lowfree[idx] + z->pages_high;

Anonymous memory is GFP_HIGHUSER, yeah? Anything wrong with

- ns->lowfree[idx] = z->pages_high * 3 + z->lowmem_reserve[idx];
+ ns->lowfree[idx] = z->pages_high * 3 + z->lowmem_reserve[ZONE_HIGHMEM];


--
SUSE Labs, Novell Inc.
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2006-05-18 07:42:36

by Con Kolivas

Subject: [PATCH][respin] mm: swap prefetch fix lowmem reserve calc

On Thursday 18 May 2006 17:18, Nick Piggin wrote:
> Anonymous memory is GFP_HIGHUSER, yeah? Anything wrong with
>
> - ns->lowfree[idx] = z->pages_high * 3 + z->lowmem_reserve[idx];
> + ns->lowfree[idx] = z->pages_high * 3 + z->lowmem_reserve[ZONE_HIGHMEM];

I guess not, thanks!
---

Correct the effect lowmem_reserve has on calculation of free limits
in swap_prefetch.

Signed-off-by: Con Kolivas <[email protected]>

---
mm/swap_prefetch.c | 3 ++-
1 files changed, 2 insertions(+), 1 deletion(-)

Index: linux-2.6.17-rc4-mm1/mm/swap_prefetch.c
===================================================================
--- linux-2.6.17-rc4-mm1.orig/mm/swap_prefetch.c 2006-05-18 15:48:22.000000000 +1000
+++ linux-2.6.17-rc4-mm1/mm/swap_prefetch.c 2006-05-18 17:24:44.000000000 +1000
@@ -276,7 +276,8 @@ static void examine_free_limits(void)

ns = &sp_stat.node[z->zone_pgdat->node_id];
idx = zone_idx(z);
- ns->lowfree[idx] = z->pages_high * 3 + z->lowmem_reserve[idx];
+ ns->lowfree[idx] = z->pages_high * 3 +
+ z->lowmem_reserve[ZONE_HIGHMEM];
ns->highfree[idx] = ns->lowfree[idx] + z->pages_high;

if (z->free_pages > ns->highfree[idx]) {

--
-ck