diff mbox series

[v3,3/6] powerpc/pseries: Account for SPURR ticks on idle CPUs

Message ID 1583919461-27405-4-git-send-email-ego@linux.vnet.ibm.com (mailing list archive)
State Changes Requested
Headers show
Series Track and expose idle PURR and SPURR ticks | expand

Checks

Context Check Description
snowpatch_ozlabs/apply_patch success Successfully applied on branch powerpc/merge (ab326587bb5fb91cc97df9b9f48e9e1469f04621)
snowpatch_ozlabs/checkpatch success total: 0 errors, 0 warnings, 0 checks, 75 lines checked
snowpatch_ozlabs/needsstable success Patch has no Fixes tags

Commit Message

Gautham R Shenoy March 11, 2020, 9:37 a.m. UTC 
From: "Gautham R. Shenoy" <ego@linux.vnet.ibm.com>

On Pseries LPARs, to calculate utilization, we need to know the
[S]PURR ticks when the CPUs were busy or idle.

Via pseries_idle_prolog(), pseries_idle_epilog(), we track the idle
PURR ticks in the VPA variable "wait_state_cycles". This patch extends
the support to account for the idle SPURR ticks. It also provides an
accessor function to accurately reads idle SPURR ticks.

Signed-off-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
---
 arch/powerpc/include/asm/idle.h        | 33 +++++++++++++++++++++++++++++++++
 arch/powerpc/platforms/pseries/setup.c |  2 ++
 2 files changed, 35 insertions(+)
diff mbox series

Patch

diff --git a/arch/powerpc/include/asm/idle.h b/arch/powerpc/include/asm/idle.h
index 7552823..a375589 100644
--- a/arch/powerpc/include/asm/idle.h
+++ b/arch/powerpc/include/asm/idle.h
@@ -3,13 +3,20 @@ 
 #define _ASM_POWERPC_IDLE_H
 #include <asm/runlatch.h>
 
+DECLARE_PER_CPU(u64, idle_spurr_cycles);
 DECLARE_PER_CPU(u64, idle_entry_purr_snap);
+DECLARE_PER_CPU(u64, idle_entry_spurr_snap);
 
 static inline void snapshot_purr_idle_entry(void)
 {
 	*this_cpu_ptr(&idle_entry_purr_snap) = mfspr(SPRN_PURR);
 }
 
+static inline void snapshot_spurr_idle_entry(void)
+{
+	*this_cpu_ptr(&idle_entry_spurr_snap) = mfspr(SPRN_SPURR);
+}
+
 static inline void update_idle_purr_accounting(void)
 {
 	u64 wait_cycles;
@@ -20,10 +27,19 @@  static inline void update_idle_purr_accounting(void)
 	get_lppaca()->wait_state_cycles = cpu_to_be64(wait_cycles);
 }
 
+static inline void update_idle_spurr_accounting(void)
+{
+	u64 *idle_spurr_cycles_ptr = this_cpu_ptr(&idle_spurr_cycles);
+	u64 in_spurr = *this_cpu_ptr(&idle_entry_spurr_snap);
+
+	*idle_spurr_cycles_ptr += mfspr(SPRN_SPURR) - in_spurr;
+}
+
 static inline void pseries_idle_prolog(void)
 {
 	ppc64_runlatch_off();
 	snapshot_purr_idle_entry();
+	snapshot_spurr_idle_entry();
 	/*
 	 * Indicate to the HV that we are idle. Now would be
 	 * a good time to find other work to dispatch.
@@ -34,6 +50,7 @@  static inline void pseries_idle_prolog(void)
 static inline void pseries_idle_epilog(void)
 {
 	update_idle_purr_accounting();
+	update_idle_spurr_accounting();
 	get_lppaca()->idle = 0;
 	ppc64_runlatch_on();
 }
@@ -53,4 +70,20 @@  static inline u64 read_this_idle_purr(void)
 
 	return be64_to_cpu(get_lppaca()->wait_state_cycles);
 }
+
+static inline u64 read_this_idle_spurr(void)
+{
+	/*
+	 * If we are reading from an idle context, update the
+	 * idle-spurr cycles corresponding to the last idle period.
+	 * Since the idle context is not yet over, take a fresh
+	 * snapshot of the idle-spurr.
+	 */
+	if (get_lppaca()->idle == 1) {
+		update_idle_spurr_accounting();
+		snapshot_spurr_idle_entry();
+	}
+
+	return *this_cpu_ptr(&idle_spurr_cycles);
+}
 #endif
diff --git a/arch/powerpc/platforms/pseries/setup.c b/arch/powerpc/platforms/pseries/setup.c
index 4905c96..1b55e80 100644
--- a/arch/powerpc/platforms/pseries/setup.c
+++ b/arch/powerpc/platforms/pseries/setup.c
@@ -318,7 +318,9 @@  static int alloc_dispatch_log_kmem_cache(void)
 }
 machine_early_initcall(pseries, alloc_dispatch_log_kmem_cache);
 
+DEFINE_PER_CPU(u64, idle_spurr_cycles);
 DEFINE_PER_CPU(u64, idle_entry_purr_snap);
+DEFINE_PER_CPU(u64, idle_entry_spurr_snap);
 static void pseries_lpar_idle(void)
 {
 	/*