On Tue, Jun 19, 2018 at 5:49 PM David Rientjes rientjes@google.com wrote:
On Tue, 19 Jun 2018, Shakeel Butt wrote:
diff --git a/mm/slub.c b/mm/slub.c index a3b8467c14af..731c02b371ae 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -3673,9 +3673,23 @@ static void free_partial(struct kmem_cache *s, struct kmem_cache_node *n)
bool __kmem_cache_empty(struct kmem_cache *s) {
int node;
int cpu, node;Nit: wouldn't cpu be unused if CONFIG_SLUB_DEBUG is disabled?
I think I didn't get the warning as I didn't use #ifdef.
struct kmem_cache_node *n;
/** slabs_node will always be 0 for !CONFIG_SLUB_DEBUG. So, manually* check slabs for all cpus.*/if (!IS_ENABLED(CONFIG_SLUB_DEBUG)) {for_each_online_cpu(cpu) {struct kmem_cache_cpu *c;c = per_cpu_ptr(s->cpu_slab, cpu);if (c->page || slub_percpu_partial(c))return false;}}for_each_kmem_cache_node(s, node, n) if (n->nr_partial || slabs_node(s, node)) return false;Wouldn't it just be better to allow {inc,dec}_slabs_node() to adjust the nr_slabs counter instead of doing the per-cpu iteration on every shutdown?
Yes that is doable as the functions {inc,dec}_slabs_node() are called in slow path. I can move them out of CONFIG_SLUB_DEBUG. I think the reason 0f389ec63077 ("slub: No need for per node slab counters if !SLUB_DEBUG") put them under CONFIG_SLUB_DEBUG is because these counters were only read through sysfs API which were disabled on !CONFIG_SLUB_DEBUG. However we have a usecase other than sysfs API.
Please let me know if there is any objection to this conversion. For large machines I think this is preferable approach.
thanks, Shakeel