Messages in this thread | | | Date | Thu, 30 Mar 2017 12:03:44 -0700 (PDT) | From | Shivappa Vikas <> | Subject | Re: [PATCH 5/5] x86/intel_rdt: hotcpu updates for RDT |
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On Wed, 1 Mar 2017, Thomas Gleixner wrote:
>> WARN_ON(c->x86_cache_occ_scale != cqm_l3_scale); >> >> @@ -1585,12 +1580,17 @@ static int intel_cqm_cpu_starting(unsigned int cpu) >> >> static int intel_cqm_cpu_exit(unsigned int cpu) >> { >> + struct intel_pqr_state *state = &per_cpu(pqr_state, cpu); > > Can be this_cpu_ptr() because the callback is guaranteed to run on the > outgoing CPU.
Will fix this. Assumed the calls are setup cache alloc way - cpuhp_setup_state(CPUHP_AP_ONLINE_DYN ..
> >> int target; >> >> /* Is @cpu the current cqm reader for this package ? */ >> if (!cpumask_test_and_clear_cpu(cpu, &cqm_cpumask)) >> return 0; > > So if the CPU is not the current cqm reader then the per cpu state of this > CPU is left stale. Great improvement. > >> + state->rmid = 0; >> + state->rmid_usecnt = 0; >> + wrmsr(MSR_IA32_PQR_ASSOC, 0, state->closid); > > What clears state->closid? And what guarantees that state->rmid is not > updated before the CPU has really gone away?
- The rdt code takes care of clearing closid state now. Will update the comment. - The cqm however was never writing a zero to PQR_ASSOC.
So the update needs to be - to remove the state->closid = 0 from cqm code as the rdt code takes care of closid state in clear_closid() called from both offline and online cpu. And also write a rmid = 0 to PQR_ASSOC.
We can integrate the two of these hot cpu calls(from cat and cqm) to write PQR only once.
guess I can skip all of these and send it as part of cqm changes we planned anyways, because this is really a cqm change.
Thanks, Vikas
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