@@ -129,6 +129,8 @@ struct user_event_mm;
__TASK_TRACED | EXIT_DEAD | EXIT_ZOMBIE | \
TASK_PARKED)
+#define IPC_CLASS_UNCLASSIFIED 0
+
#define task_is_running(task) (READ_ONCE((task)->__state) == TASK_RUNNING)
#define task_is_traced(task) ((READ_ONCE(task->jobctl) & JOBCTL_TRACED) != 0)
@@ -1534,6 +1536,14 @@ struct task_struct {
struct user_event_mm *user_event_mm;
#endif
+#ifdef CONFIG_IPC_CLASSES
+ /*
+ * A hardware-defined classification of task that reflects but is
+ * not identical to the number of instructions per cycle.
+ */
+ unsigned short ipcc;
+#endif
+
/*
* New fields for task_struct should be added above here, so that
* they are included in the randomized portion of task_struct.
@@ -839,6 +839,18 @@ config UCLAMP_BUCKETS_COUNT
If in doubt, use the default value.
+config IPC_CLASSES
+ bool "IPC classes of tasks"
+ depends on SMP
+ help
+ If selected, each task is assigned a classification value that
+ reflects the type of instructions that the task executes. This
+ classification reflects but is not equal to the number of
+ instructions retired per cycle.
+
+ The scheduler uses the classification value to improve the placement
+ of tasks.
+
endmenu
#
On hybrid processors, the architecture differences between the types of CPUs result in different instructions-per-cycle (IPC) rates for each type of CPU. IPCs may vary further by the type of instructions being executed. Instructions can be grouped into classes of similar IPCs. Tasks can be classified into groups based on the type of instructions they execute. Add a new member task_struct::ipcc to associate a particular task to an IPC class that depends on the instructions it executes. The scheduler may use the IPC class of a task and data about the performance among CPUs of a given IPC class to improve throughput. It may, for instance, place certain classes of tasks on CPUs of higher performance. The methods to determine the classification of a task and its relative IPC score are specific to each CPU architecture. 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: Perry Yuan <Perry.Yuan@amd.com> 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: Zhao Liu <zhao1.liu@linux.intel.com> Cc: x86@kernel.org Cc: linux-pm@vger.kernel.org Cc: linux-kernel@vger.kernel.org Signed-off-by: Ricardo Neri <ricardo.neri-calderon@linux.intel.com> --- Changes since v3: * None Changes since v2: * Changed the type of task_struct::ipcc to unsigned short. A subsequent patch uses bit fields to use 9 bits, along with other auxiliary members. Changes since v1: * Renamed task_struct::class as task_struct::ipcc. (Joel) * Use task_struct::ipcc = 0 for unclassified tasks. (PeterZ) * Renamed CONFIG_SCHED_TASK_CLASSES as CONFIG_IPC_CLASSES. (PeterZ, Joel) --- include/linux/sched.h | 10 ++++++++++ init/Kconfig | 12 ++++++++++++ 2 files changed, 22 insertions(+)