Messages in this thread | | | Date | Tue, 4 Jan 2011 15:22:03 +0100 | From | Borislav Petkov <> | Subject | Re: [PATCH 5/7] perf: Optimise topology iteration |
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Adding Andreas since this is his code.
On Tue, Jan 04, 2011 at 07:06:16AM -0500, Peter Zijlstra wrote: > On Mon, 2010-12-27 at 23:38 +0800, Lin Ming wrote: > > Currently we iterate the full machine looking for a matching core_id/nb > > for the percore and the amd northbridge stuff , using a smaller topology > > mask makes sense. > > > > Signed-off-by: Lin Ming <ming.m.lin@intel.com> > > --- > > arch/x86/kernel/cpu/perf_event_amd.c | 2 +- > > arch/x86/kernel/cpu/perf_event_intel.c | 2 +- > > 2 files changed, 2 insertions(+), 2 deletions(-) > > > > diff --git a/arch/x86/kernel/cpu/perf_event_amd.c b/arch/x86/kernel/cpu/perf_event_amd.c > > index 67e2202..5a3b7b8 100644 > > --- a/arch/x86/kernel/cpu/perf_event_amd.c > > +++ b/arch/x86/kernel/cpu/perf_event_amd.c > > @@ -323,7 +323,7 @@ static void amd_pmu_cpu_starting(int cpu) > > nb_id = amd_get_nb_id(cpu); > > WARN_ON_ONCE(nb_id == BAD_APICID); > > > > - for_each_online_cpu(i) { > > + for_each_cpu(i, topology_core_cpumask(cpu)) { > > nb = per_cpu(cpu_hw_events, i).amd_nb; > > if (WARN_ON_ONCE(!nb)) > > continue; > > Borislav, is topology_core_cpumask() the right mask for northbridge_id > span? I could imagine Magny-Cours would have all 12 cores in the > core_cpumask() and have the node_mask() be half that.
So, topology_core_cpumask() or cpu_core_mask() both are cpu_core_map which represents the socket mask. I.e., on a multisocket cpu you'll have in it all the cores on one socket. A 12-cores Magny-Cours contains two internal northbridges and this mask will have 12 bits set.
AFAICT, you want to iterate over the cores on a single node here (an internal node in the Magny-Cours case) so for this we have the llc_shared_map. See near the top of cache_shared_cpu_map_setup() in <arch/x86/kernel/cpu/intel_cacheinfo.c> for an example.
node_mask() is roughly the same but contains correct info only with CONFIG_NUMA on and correct SRAT table on the system.
HTH.
-- Regards/Gruss, Boris.
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