Messages in this thread | | | Date | Fri, 7 Nov 2014 13:38:36 +0100 | From | Peter Zijlstra <> | Subject | Re: [PATCH v3 10/11] perf/x86/intel: Perform rotation on Intel CQM RMIDs |
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On Fri, Nov 07, 2014 at 01:34:31PM +0100, Peter Zijlstra wrote: > > enum rmid_cycle_state { > RMID_AVAILABLE = 0, > RMID_LIMBO, > RMID_YOUNG, > }; > > struct cqm_rmid_entry { > ... > enum rmid_cycle_state state; > }; > > static void __intel_sqm_stable(void *arg) > { > list_for_each_entry(entry, &cqm_rmid_limbo_lru, list) { > if (entry->state == RMID_YOUNG) > break; > > if (__rmid_read(entry->rmid) > __threshold) > entry->state = RMID_LIMBO; > } > } > > static bool intel_cqm_rmid_stabilize() > { > unsigned long queue_time = jiffies + msecs_to_jiffies(__rotation_period); > unsigned int nr_limbo = 0; > ... > > list_for_each_entry(entry, &cqm_rmid_limbo_lru, list) { > if (time_after(entry->queue_time, queue_time)) > break; > > entry->state = RMID_AVAILABLE; > nr_limbo++;
For optional goodness:
if (nr_limbo > max_scan_size) break;
Which will limit the number of RMIDs you'll scan from the IPI, and thereby limit the time taken there.
> } > > if (!nr_limbo) > return; > > on_each_cpu_mask(&cqm_cpumask, __intel_cqm_stable, NULL, true); > > list_for_each_entry_safe(entry, tmp, &cqm_rmid_limbo_lru, list) { > if (entry->state == RMID_YOUNG) > break; > > if (entry->state == RMID_AVAILABLE) > list_move(&cqm_rmid_free_list, &entry->list); > } > } > > > Would not something like that work?
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