On Wed, 28 Nov 2007 17:49:23 +0900
KAMEZAWA Hiroyuki <[EMAIL PROTECTED]> wrote:
> Hi, this set is for memory controller background reclaim.
>
> Merged YAMAMOTO-san's version onto 2.6.23-rc3-mm1 + my NUMA patch.
> And splitted to several sets.
>
> Major changes from his one is
> - use kthread instead of work_queue
> - adjust high/low watermark when limit changes automatically
> and set default value. (a user can specify his own later.)
>
FYI rather than RFC.
I wrote attached patch and run kernbench on 8CPU/2Node NUMA/ia64.
It does make -j 32.
Memory limitation was 800M. Low/High watermark here was 750M/780M.
== These numbers are stable to some extent.==
2.6.24-rc3-mm2: (Limit: 800M)
Average Optimal -j 32 Load Run:
Elapsed Time 358.933---------------------------(*)
User Time 1069.63
System Time 140.667
Percent CPU 337.333
Context Switches 220821
Sleeps 196912
2.6.24-rc3-mm2 + throttle (Limit:800M)
Average Optimal -j 32 Load Run:
Elapsed Time 266.697---------------------------(*)
User Time 1105.39
System Time 124.423
Percent CPU 471.667
Context Switches 251797
Sleeps 231038
2.6.24-rc3-mm2 + throttle + High/Low watermark.
(low:750M High:780M Limit:800M)
Average Optimal -j 32 Load Run:
Elapsed Time 266.844---------------------------(*)
User Time 1112.9
System Time 112.273
Percent CPU 473.667
Context Switches 251795
Sleeps 220339
==
Seems throttling reclaim has some good effect (for kernbench).
Does anyone have an idea for throttling reclaiming of memory controller ?
Thanks,
-Kame
==
Just and Experimental. add throttling at starting direct reclaim.
mm/memcontrol.c | 22 ++++++++++++++++++----
1 file changed, 18 insertions(+), 4 deletions(-)
Index: linux-2.6.24-rc3-mm2/mm/memcontrol.c
===================================================================
--- linux-2.6.24-rc3-mm2.orig/mm/memcontrol.c
+++ linux-2.6.24-rc3-mm2/mm/memcontrol.c
@@ -133,6 +133,7 @@ struct mem_cgroup {
unsigned long control_type; /* control RSS or RSS+Pagecache */
int prev_priority; /* for recording reclaim priority */
+ atomic_t reclaimers; /* # of processes which calls reclaim */
/*
* statistics.
*/
@@ -635,14 +636,27 @@ retry:
*/
while (res_counter_charge(&mem->res, PAGE_SIZE)) {
bool is_atomic = gfp_mask & GFP_ATOMIC;
+ int limit;
/*
* We cannot reclaim under GFP_ATOMIC, fail the charge
*/
if (is_atomic)
goto noreclaim;
-
- if (try_to_free_mem_cgroup_pages(mem, gfp_mask))
- continue;
+ /*
+ * Experimental:
+ * Obviously, we need some throttling here.
+ */
+ limit = num_online_cpus()/4 + 1;
+ if (atomic_add_unless(&mem->reclaimers, 1, limit)) {
+ if (try_to_free_mem_cgroup_pages(mem, gfp_mask)) {
+ atomic_dec(&mem->reclaimers);
+ continue;
+ }
+ atomic_dec(&mem->reclaimers);
+ } else {
+ yield();
+ nr_retries++;
+ }
/*
* try_to_free_mem_cgroup_pages() might not give us a full
@@ -1168,7 +1182,7 @@ mem_cgroup_create(struct cgroup_subsys *
mem->control_type = MEM_CGROUP_TYPE_ALL;
memset(&mem->info, 0, sizeof(mem->info));
-
+ atomic_set(&mem->reclaimers, 0);
for_each_node_state(node, N_POSSIBLE)
if (alloc_mem_cgroup_per_zone_info(mem, node))
goto free_out;
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