Messages in this thread | | | From | "Rafael J. Wysocki" <> | Date | Wed, 29 Mar 2023 14:08:30 +0200 | Subject | Re: [PATCH v3 13/24] thermal: intel: hfi: Store per-CPU IPCC scores |
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On Wed, Mar 29, 2023 at 1:32 AM Ricardo Neri <ricardo.neri-calderon@linux.intel.com> wrote: > > On Mon, Mar 27, 2023 at 06:37:32PM +0200, Rafael J. Wysocki wrote: > > On Tue, Feb 7, 2023 at 6:02 AM Ricardo Neri > > <ricardo.neri-calderon@linux.intel.com> wrote: > > > > > > The scheduler reads the IPCC scores when balancing load. These reads can > > > be quite frequent. Hardware can also update the HFI table frequently. > > > Concurrent access may cause a lot of lock contention. It gets worse as the > > > number of CPUs increases. > > > > > > Instead, create separate per-CPU IPCC scores that the scheduler can read > > > without the HFI table lock. > > > > > > Cc: Ben Segall <bsegall@google.com> > > > Cc: Daniel Bristot de Oliveira <bristot@redhat.com> > > > Cc: Dietmar Eggemann <dietmar.eggemann@arm.com> > > > Cc: Ionela Voinescu <ionela.voinescu@arm.com> > > > Cc: Joel Fernandes (Google) <joel@joelfernandes.org> > > > Cc: Len Brown <len.brown@intel.com> > > > Cc: Lukasz Luba <lukasz.luba@arm.com> > > > Cc: Mel Gorman <mgorman@suse.de> > > > Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com> > > > Cc: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com> > > > Cc: Steven Rostedt <rostedt@goodmis.org> > > > Cc: Tim C. Chen <tim.c.chen@intel.com> > > > Cc: Valentin Schneider <vschneid@redhat.com> > > > Cc: x86@kernel.org > > > Cc: linux-pm@vger.kernel.org > > > Cc: linux-kernel@vger.kernel.org > > > Suggested-by: Peter Zijlstra (Intel) <peterz@infradead.org> > > > Signed-off-by: Ricardo Neri <ricardo.neri-calderon@linux.intel.com> > > > --- > > > Changes since v2: > > > * Only create these per-CPU variables when Intel Thread Director is > > > supported. > > > > > > Changes since v1: > > > * Added this patch. > > > --- > > > drivers/thermal/intel/intel_hfi.c | 46 +++++++++++++++++++++++++++++++ > > > 1 file changed, 46 insertions(+) > > > > > > diff --git a/drivers/thermal/intel/intel_hfi.c b/drivers/thermal/intel/intel_hfi.c > > > index 2527ae3836c7..b06021828892 100644 > > > --- a/drivers/thermal/intel/intel_hfi.c > > > +++ b/drivers/thermal/intel/intel_hfi.c > > > @@ -29,6 +29,7 @@ > > > #include <linux/kernel.h> > > > #include <linux/math.h> > > > #include <linux/mutex.h> > > > +#include <linux/percpu.h> > > > #include <linux/percpu-defs.h> > > > #include <linux/printk.h> > > > #include <linux/processor.h> > > > @@ -170,6 +171,43 @@ static struct workqueue_struct *hfi_updates_wq; > > > #define HFI_UPDATE_INTERVAL HZ > > > #define HFI_MAX_THERM_NOTIFY_COUNT 16 > > > > > > +#ifdef CONFIG_IPC_CLASSES > > > > It would be good to provide a (concise) description of this variable. > > > > > +static int __percpu *hfi_ipcc_scores; > > Do you mean hfi_ipcc_scores or CONFIG_IPC_CLASSES?
hfi_ipcc_scores (as the latter is not a variable).
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