On Mon, 4 Feb 2008 22:20:04 -0800 (PST) Christoph Lameter <[EMAIL PROTECTED]>
wrote:
> The statistics provided here allow the monitoring of allocator behavior
> at the cost of some (minimal) loss of performance. Counters are placed in
> SLUB's per cpu data structure that is already written to by other code.
Seems sane.
> The per cpu structure may be extended by the statistics to be more than
> one cacheline which will increase the cache footprint of SLUB.
>
> That is why there is a compile option to enable/disable the inclusion of
> the statistics module.
The compile-time optionality is really sad. But no obvious solution
suggests itself.
> @@ -1357,17 +1366,22 @@ static struct page *get_partial(struct k
> static void unfreeze_slab(struct kmem_cache *s, struct page *page, int tail)
> {
> struct kmem_cache_node *n = get_node(s, page_to_nid(page));
> + struct kmem_cache_cpu *c = get_cpu_slab(s, smp_processor_id());
So we're never running preemptibly here.
> ClearSlabFrozen(page);
> if (page->inuse) {
>
> - if (page->freelist != page->end)
> + if (page->freelist != page->end) {
> add_partial(n, page, tail);
> - else if (SlabDebug(page) && (s->flags & SLAB_STORE_USER))
> + stat(c, tail ? DEACTIVATE_TO_TAIL : DEACTIVATE_TO_HEAD);
> + } else {
> + stat(c, DEACTIVATE_FULL);
> + if (SlabDebug(page) && (s->flags & SLAB_STORE_USER))
> add_full(n, page);
missing a tab
> +#ifdef CONFIG_SLUB_STATS
> +
> +#define STAT_ATTR(si, text) \
> +static ssize_t text##_show(struct kmem_cache *s, char *buf) \
> +{ \
> + unsigned long sum = 0; \
> + int cpu; \
> + \
> + for_each_online_cpu(cpu) \
> + sum += get_cpu_slab(s, cpu)->stat[si]; \
maybe cache the get_cpu_slab() result in a local?
> + return sprintf(buf, "%lu\n", sum); \
> +} \
> +SLAB_ATTR_RO(text); \
this is pretty broken after cpu hot-unplug, isn't it?
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