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Commit 748b6b88 authored by Vikas Shivappa's avatar Vikas Shivappa Committed by Thomas Gleixner
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x86/intel_rdt/cqm: Add sched_in support 



OS associates an RMID/CLOSid to a task by writing the per CPU
IA32_PQR_ASSOC MSR when a task is scheduled in.

The sched_in code will stay as no-op unless we are running on Intel SKU
which supports either resource control or monitoring and we also enable
them by mounting the resctrl fs.  The per cpu CLOSid/RMID values are
cached and the write is performed only when a task with a different
CLOSid/RMID is scheduled in.

Signed-off-by: default avatarVikas Shivappa <vikas.shivappa@linux.intel.com>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Cc: ravi.v.shankar@intel.com
Cc: tony.luck@intel.com
Cc: fenghua.yu@intel.com
Cc: peterz@infradead.org
Cc: eranian@google.com
Cc: vikas.shivappa@intel.com
Cc: ak@linux.intel.com
Cc: davidcc@google.com
Cc: reinette.chatre@intel.com
Link: http://lkml.kernel.org/r/1501017287-28083-25-git-send-email-vikas.shivappa@linux.intel.com
parent 4be6c078

arch/x86/include/asm/intel_rdt_sched.h

+29 −21
Original line number Diff line number Diff line
@@ -15,7 +15,8 @@ 
 *

 * The upper 32 bits of IA32_PQR_ASSOC contain closid and the

 * lower 10 bits rmid. The update to IA32_PQR_ASSOC always

 * contains both parts, so we need to cache them.

 * contains both parts, so we need to cache them. This also

 * stores the user configured per cpu CLOSID and RMID.

 *

 * The cache also helps to avoid pointless updates if the value does

 * not change.
@@ -30,38 +31,45 @@ DECLARE_PER_CPU_READ_MOSTLY(struct intel_pqr_state, rdt_cpu_default); 


DECLARE_STATIC_KEY_FALSE(rdt_enable_key);

DECLARE_STATIC_KEY_FALSE(rdt_alloc_enable_key);

DECLARE_STATIC_KEY_FALSE(rdt_mon_enable_key);



/*

 * __intel_rdt_sched_in() - Writes the task's CLOSid to IA32_PQR_MSR

 * __intel_rdt_sched_in() - Writes the task's CLOSid/RMID to IA32_PQR_MSR

 *

 * Following considerations are made so that this has minimal impact

 * on scheduler hot path:

 * - This will stay as no-op unless we are running on an Intel SKU

 *   which supports resource control and we enable by mounting the

 *   resctrl file system.

 * - Caches the per cpu CLOSid values and does the MSR write only

 *   when a task with a different CLOSid is scheduled in.

 *

 *   which supports resource control or monitoring and we enable by

 *   mounting the resctrl file system.

 * - Caches the per cpu CLOSid/RMID values and does the MSR write only

 *   when a task with a different CLOSid/RMID is scheduled in.

 * - We allocate RMIDs/CLOSids globally in order to keep this as

 *   simple as possible.

 * Must be called with preemption disabled.

 */

static inline void __intel_rdt_sched_in(void)

static void __intel_rdt_sched_in(void)

{

	if (static_branch_likely(&rdt_alloc_enable_key)) {

		struct intel_pqr_state *state = this_cpu_ptr(&pqr_state);

		u32 closid;

	struct intel_pqr_state newstate = this_cpu_read(rdt_cpu_default);

	struct intel_pqr_state *curstate = this_cpu_ptr(&pqr_state);



	/*

		 * If this task has a closid assigned, use it.

		 * Else use the closid assigned to this cpu.

	 * If this task has a closid/rmid assigned, use it.

	 * Else use the closid/rmid assigned to this cpu.

	 */

		closid = current->closid;

		if (closid == 0)

			closid = this_cpu_read(rdt_cpu_default.closid);

	if (static_branch_likely(&rdt_alloc_enable_key)) {

		if (current->closid)

			newstate.closid = current->closid;

	}



		if (closid != state->closid) {

			state->closid = closid;

			wrmsr(IA32_PQR_ASSOC, state->rmid, closid);

	if (static_branch_likely(&rdt_mon_enable_key)) {

		if (current->rmid)

			newstate.rmid = current->rmid;

	}



	if (newstate.closid != curstate->closid ||

	    newstate.rmid != curstate->rmid) {

		*curstate = newstate;

		wrmsr(IA32_PQR_ASSOC, newstate.rmid, newstate.closid);

	}

}

arch/x86/kernel/cpu/intel_rdt.h

+0 −4
Original line number Diff line number Diff line
@@ -22,8 +22,6 @@ 
#define RMID_VAL_ERROR			BIT_ULL(63)

#define RMID_VAL_UNAVAIL		BIT_ULL(62)



DECLARE_STATIC_KEY_FALSE(rdt_enable_key);



/**

 * struct mon_evt - Entry in the event list of a resource

 * @evtid:		event id
@@ -61,8 +59,6 @@ extern bool rdt_alloc_capable; 
extern bool rdt_mon_capable;

extern unsigned int rdt_mon_features;



DECLARE_STATIC_KEY_FALSE(rdt_mon_enable_key);



enum rdt_group_type {

	RDTCTRL_GROUP = 0,

	RDTMON_GROUP,