Re: [RFC PATCH v2 2/4] cpuidle: (POWER) cpuidle driver for pSeries
On 11/28/2011 04:33 AM, Benjamin Herrenschmidt wrote:
On Thu, 2011-11-17 at 16:58 +0530, Deepthi Dharwar wrote:
This patch implements a backhand cpuidle driver for pSeries
based on pseries_dedicated_idle_loop and pseries_shared_idle_loop
routines. The driver is built only if CONFIG_CPU_IDLE is set. This
cpuidle driver uses global registration of idle states and
not per-cpu.
.../...
+#define MAX_IDLE_STATE_COUNT2
+
+static int max_cstate = MAX_IDLE_STATE_COUNT - 1;
Why cstate ? This isn't an x86 :-)
Sure, I shall change it right away :)
+static struct cpuidle_device __percpu *pseries_idle_cpuidle_devices;
Shorter name please. pseries_cpuidle_devs is fine.
I ll do so.
+static struct cpuidle_state *cpuidle_state_table;
+
+void update_smt_snooze_delay(int snooze)
+{
+struct cpuidle_driver *drv = cpuidle_get_driver();
+if (drv)
+drv-states[0].target_residency = snooze;
+}
+
+static inline void idle_loop_prolog(unsigned long *in_purr, ktime_t
*kt_before)
+{
+
+*kt_before = ktime_get_real();
+*in_purr = mfspr(SPRN_PURR);
+/*
+ * Indicate to the HV that we are idle. Now would be
+ * a good time to find other work to dispatch.
+ */
+get_lppaca()-idle = 1;
+get_lppaca()-donate_dedicated_cpu = 1;
+}
I notice that you call this on shared processors as well. The old ocde
used to not set donate_dedicated_cpu in that case. I assume that's not a
big deal and that the HV will just ignore it in the shared processor
case but please add a comment after you've verified it.
Yes, the old code does not set donate_dedicated_cpu. But yes I will
try testing it in a shared proc config but also remove this
initialization for shared idle loop.
+static inline s64 idle_loop_epilog(unsigned long in_purr, ktime_t
kt_before)
+{
+get_lppaca()-wait_state_cycles += mfspr(SPRN_PURR) - in_purr;
+get_lppaca()-donate_dedicated_cpu = 0;
+get_lppaca()-idle = 0;
+
+return ktime_to_us(ktime_sub(ktime_get_real(), kt_before));
+}
+
+
+static int snooze_loop(struct cpuidle_device *dev,
+struct cpuidle_driver *drv,
+int index)
+{
+unsigned long in_purr;
+ktime_t kt_before;
+
+idle_loop_prolog(in_purr, kt_before);
+
+local_irq_enable();
+set_thread_flag(TIF_POLLING_NRFLAG);
+while (!need_resched()) {
+ppc64_runlatch_off();
+HMT_low();
+HMT_very_low();
+}
+HMT_medium();
+clear_thread_flag(TIF_POLLING_NRFLAG);
+smp_mb();
+local_irq_disable();
+
+dev-last_residency =
+(int)idle_loop_epilog(in_purr, kt_before);
+return index;
+}
So your snooze loop has no timeout, is that handled by the cpuidle
driver using some kind of timer ? That sounds a lot less efficient than
passing a max delay to the snooze loop to handle getting into a deeper
state after a bit of snoozing rather than interrupting etc...
My bad, snooze_loop is essential for a time out. Nope cpuidle
driver doesn't have any timer mechanism. I ll fix it.
Need to add loop for snooze time.
+static int dedicated_cede_loop(struct cpuidle_device *dev,
+struct cpuidle_driver *drv,
+int index)
+{
+unsigned long in_purr;
+ktime_t kt_before;
+
+idle_loop_prolog(in_purr, kt_before);
+
+ppc64_runlatch_off();
+HMT_medium();
+cede_processor();
+
+dev-last_residency =
+(int)idle_loop_epilog(in_purr, kt_before);
+return index;
+}
+
+static int shared_cede_loop(struct cpuidle_device *dev,
+struct cpuidle_driver *drv,
+int index)
+{
+unsigned long in_purr;
+ktime_t kt_before;
+
+idle_loop_prolog(in_purr, kt_before);
+
+/*
+ * Yield the processor to the hypervisor. We return if
+ * an external interrupt occurs (which are driven prior
+ * to returning here) or if a prod occurs from another
+ * processor. When returning here, external interrupts
+ * are enabled.
+ */
+cede_processor();
+
+dev-last_residency =
+(int)idle_loop_epilog(in_purr, kt_before);
+return index;
+}
+
+/*
+ * States for dedicated partition case.
+ */
+static struct cpuidle_state dedicated_states[MAX_IDLE_STATE_COUNT] = {
+{ /* Snooze */
+.name = snooze,
+.desc = snooze,
+.flags = CPUIDLE_FLAG_TIME_VALID,
+.exit_latency = 0,
+.target_residency = 0,
+.enter = snooze_loop },
+{ /* CEDE */
+.name = CEDE,
+.desc = CEDE,
+.flags = CPUIDLE_FLAG_TIME_VALID,
+.exit_latency = 1,
+.target_residency = 10,
+.enter = dedicated_cede_loop },
+};
+
+/*
+ * States for shared partition case.
+ */
+static struct cpuidle_state
Re: [RFC PATCH v2 2/4] cpuidle: (POWER) cpuidle driver for pSeries
On Thu, 2011-11-17 at 16:58 +0530, Deepthi Dharwar wrote:
This patch implements a backhand cpuidle driver for pSeries
based on pseries_dedicated_idle_loop and pseries_shared_idle_loop
routines. The driver is built only if CONFIG_CPU_IDLE is set. This
cpuidle driver uses global registration of idle states and
not per-cpu.
.../...
+#define MAX_IDLE_STATE_COUNT 2
+
+static int max_cstate = MAX_IDLE_STATE_COUNT - 1;
Why cstate ? This isn't an x86 :-)
+static struct cpuidle_device __percpu *pseries_idle_cpuidle_devices;
Shorter name please. pseries_cpuidle_devs is fine.
+static struct cpuidle_state *cpuidle_state_table;
+
+void update_smt_snooze_delay(int snooze)
+{
+ struct cpuidle_driver *drv = cpuidle_get_driver();
+ if (drv)
+ drv-states[0].target_residency = snooze;
+}
+
+static inline void idle_loop_prolog(unsigned long *in_purr, ktime_t
*kt_before)
+{
+
+ *kt_before = ktime_get_real();
+ *in_purr = mfspr(SPRN_PURR);
+ /*
+ * Indicate to the HV that we are idle. Now would be
+ * a good time to find other work to dispatch.
+ */
+ get_lppaca()-idle = 1;
+ get_lppaca()-donate_dedicated_cpu = 1;
+}
I notice that you call this on shared processors as well. The old ocde
used to not set donate_dedicated_cpu in that case. I assume that's not a
big deal and that the HV will just ignore it in the shared processor
case but please add a comment after you've verified it.
+static inline s64 idle_loop_epilog(unsigned long in_purr, ktime_t kt_before)
+{
+ get_lppaca()-wait_state_cycles += mfspr(SPRN_PURR) - in_purr;
+ get_lppaca()-donate_dedicated_cpu = 0;
+ get_lppaca()-idle = 0;
+
+ return ktime_to_us(ktime_sub(ktime_get_real(), kt_before));
+}
+
+
+static int snooze_loop(struct cpuidle_device *dev,
+ struct cpuidle_driver *drv,
+ int index)
+{
+ unsigned long in_purr;
+ ktime_t kt_before;
+
+ idle_loop_prolog(in_purr, kt_before);
+
+ local_irq_enable();
+ set_thread_flag(TIF_POLLING_NRFLAG);
+ while (!need_resched()) {
+ ppc64_runlatch_off();
+ HMT_low();
+ HMT_very_low();
+ }
+ HMT_medium();
+ clear_thread_flag(TIF_POLLING_NRFLAG);
+ smp_mb();
+ local_irq_disable();
+
+ dev-last_residency =
+ (int)idle_loop_epilog(in_purr, kt_before);
+ return index;
+}
So your snooze loop has no timeout, is that handled by the cpuidle
driver using some kind of timer ? That sounds a lot less efficient than
passing a max delay to the snooze loop to handle getting into a deeper
state after a bit of snoozing rather than interrupting etc...
+static int dedicated_cede_loop(struct cpuidle_device *dev,
+ struct cpuidle_driver *drv,
+ int index)
+{
+ unsigned long in_purr;
+ ktime_t kt_before;
+
+ idle_loop_prolog(in_purr, kt_before);
+
+ ppc64_runlatch_off();
+ HMT_medium();
+ cede_processor();
+
+ dev-last_residency =
+ (int)idle_loop_epilog(in_purr, kt_before);
+ return index;
+}
+
+static int shared_cede_loop(struct cpuidle_device *dev,
+ struct cpuidle_driver *drv,
+ int index)
+{
+ unsigned long in_purr;
+ ktime_t kt_before;
+
+ idle_loop_prolog(in_purr, kt_before);
+
+ /*
+ * Yield the processor to the hypervisor. We return if
+ * an external interrupt occurs (which are driven prior
+ * to returning here) or if a prod occurs from another
+ * processor. When returning here, external interrupts
+ * are enabled.
+ */
+ cede_processor();
+
+ dev-last_residency =
+ (int)idle_loop_epilog(in_purr, kt_before);
+ return index;
+}
+
+/*
+ * States for dedicated partition case.
+ */
+static struct cpuidle_state dedicated_states[MAX_IDLE_STATE_COUNT] = {
+ { /* Snooze */
+ .name = snooze,
+ .desc = snooze,
+ .flags = CPUIDLE_FLAG_TIME_VALID,
+ .exit_latency = 0,
+ .target_residency = 0,
+ .enter = snooze_loop },
+ { /* CEDE */
+ .name = CEDE,
+ .desc = CEDE,
+ .flags = CPUIDLE_FLAG_TIME_VALID,
+ .exit_latency = 1,
+ .target_residency = 10,
+ .enter = dedicated_cede_loop },
+};
+
+/*
+ * States for shared partition case.
+ */
+static struct cpuidle_state shared_states[MAX_IDLE_STATE_COUNT] = {
+ { /* Shared Cede */
+ .name = Shared Cede,
+ .desc = Shared Cede,
+ .flags = CPUIDLE_FLAG_TIME_VALID,
+ .exit_latency = 0,
+ .target_residency = 0,
+ .enter = shared_cede_loop },
+};
+
+int pseries_notify_cpuidle_add_cpu(int cpu)
+{
+ struct cpuidle_device
[RFC PATCH v2 2/4] cpuidle: (POWER) cpuidle driver for pSeries
This patch implements a backhand cpuidle driver for pSeries
based on pseries_dedicated_idle_loop and pseries_shared_idle_loop
routines. The driver is built only if CONFIG_CPU_IDLE is set. This
cpuidle driver uses global registration of idle states and
not per-cpu.
Signed-off-by: Deepthi Dharwar deep...@linux.vnet.ibm.com
Signed-off-by: Trinabh Gupta g.trin...@gmail.com
Signed-off-by: Arun R Bharadwaj arun.r.bharad...@gmail.com
---
arch/powerpc/include/asm/system.h |8 +
arch/powerpc/kernel/sysfs.c |2
arch/powerpc/platforms/pseries/Kconfig |9 +
arch/powerpc/platforms/pseries/Makefile |1
arch/powerpc/platforms/pseries/processor_idle.c | 317 +++
arch/powerpc/platforms/pseries/pseries.h|3
arch/powerpc/platforms/pseries/setup.c |3
arch/powerpc/platforms/pseries/smp.c|1
8 files changed, 341 insertions(+), 3 deletions(-)
create mode 100644 arch/powerpc/platforms/pseries/processor_idle.c
diff --git a/arch/powerpc/include/asm/system.h
b/arch/powerpc/include/asm/system.h
index ff66680..f56a0a7 100644
--- a/arch/powerpc/include/asm/system.h
+++ b/arch/powerpc/include/asm/system.h
@@ -223,6 +223,14 @@ extern void *zalloc_maybe_bootmem(size_t size, gfp_t mask);
extern int powersave_nap; /* set if nap mode can be used in idle loop */
void cpu_idle_wait(void);
+#ifdef CONFIG_PSERIES_IDLE
+extern void update_smt_snooze_delay(int snooze);
+extern int pseries_notify_cpuidle_add_cpu(int cpu);
+#else
+static inline void update_smt_snooze_delay(int snooze) {}
+static inline int pseries_notify_cpuidle_add_cpu(int cpu) { return 0; }
+#endif
+
/*
* Atomic exchange
*
diff --git a/arch/powerpc/kernel/sysfs.c b/arch/powerpc/kernel/sysfs.c
index ce035c1..ebe5d78 100644
--- a/arch/powerpc/kernel/sysfs.c
+++ b/arch/powerpc/kernel/sysfs.c
@@ -18,6 +18,7 @@
#include asm/machdep.h
#include asm/smp.h
#include asm/pmc.h
+#include asm/system.h
#include cacheinfo.h
@@ -51,6 +52,7 @@ static ssize_t store_smt_snooze_delay(struct sys_device *dev,
return -EINVAL;
per_cpu(smt_snooze_delay, cpu-sysdev.id) = snooze;
+ update_smt_snooze_delay(snooze);
return count;
}
diff --git a/arch/powerpc/platforms/pseries/Kconfig
b/arch/powerpc/platforms/pseries/Kconfig
index c81f6bb..ae7b6d4 100644
--- a/arch/powerpc/platforms/pseries/Kconfig
+++ b/arch/powerpc/platforms/pseries/Kconfig
@@ -120,3 +120,12 @@ config DTL
which are accessible through a debugfs file.
Say N if you are unsure.
+
+config PSERIES_IDLE
+ tristate Cpuidle driver for pSeries platforms
+ depends on CPU_IDLE
+ depends on PPC_PSERIES
+ default y
+ help
+ Select this option to enable processor idle state management
+ through cpuidle subsystem.
diff --git a/arch/powerpc/platforms/pseries/Makefile
b/arch/powerpc/platforms/pseries/Makefile
index 3556e40..236db46 100644
--- a/arch/powerpc/platforms/pseries/Makefile
+++ b/arch/powerpc/platforms/pseries/Makefile
@@ -22,6 +22,7 @@ obj-$(CONFIG_PHYP_DUMP) += phyp_dump.o
obj-$(CONFIG_CMM) += cmm.o
obj-$(CONFIG_DTL) += dtl.o
obj-$(CONFIG_IO_EVENT_IRQ) += io_event_irq.o
+obj-$(CONFIG_PSERIES_IDLE) += processor_idle.o
ifeq ($(CONFIG_PPC_PSERIES),y)
obj-$(CONFIG_SUSPEND) += suspend.o
diff --git a/arch/powerpc/platforms/pseries/processor_idle.c
b/arch/powerpc/platforms/pseries/processor_idle.c
new file mode 100644
index 000..b5addd7
--- /dev/null
+++ b/arch/powerpc/platforms/pseries/processor_idle.c
@@ -0,0 +1,317 @@
+/*
+ * processor_idle - idle state cpuidle driver.
+ * Adapted from drivers/idle/intel_idle.c and
+ * drivers/acpi/processor_idle.c
+ *
+ */
+
+#include linux/kernel.h
+#include linux/module.h
+#include linux/init.h
+#include linux/moduleparam.h
+#include linux/cpuidle.h
+#include linux/cpu.h
+
+#include asm/paca.h
+#include asm/reg.h
+#include asm/system.h
+#include asm/machdep.h
+#include asm/firmware.h
+
+#include plpar_wrappers.h
+#include pseries.h
+
+struct cpuidle_driver pseries_idle_driver = {
+ .name = pseries_idle,
+ .owner =THIS_MODULE,
+};
+
+#define MAX_IDLE_STATE_COUNT 2
+
+static int max_cstate = MAX_IDLE_STATE_COUNT - 1;
+static struct cpuidle_device __percpu *pseries_idle_cpuidle_devices;
+static struct cpuidle_state *cpuidle_state_table;
+
+void update_smt_snooze_delay(int snooze)
+{
+ struct cpuidle_driver *drv = cpuidle_get_driver();
+ if (drv)
+ drv-states[0].target_residency = snooze;
+}
+
+static inline void idle_loop_prolog(unsigned long *in_purr, ktime_t *kt_before)
+{
+
+ *kt_before = ktime_get_real();
+ *in_purr = mfspr(SPRN_PURR);
+ /*
+* Indicate to the HV that we are idle. Now would be
+* a good time to find other work to dispatch.
+*/
+ get_lppaca()-idle = 1;
+
