From: "Gautham R. Shenoy" <ego@linux.vnet.ibm.com> To: Nathan Lynch <nathanl@linux.ibm.com>, Michael Ellerman <mpe@ellerman.id.au>, Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>, Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>, "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com>, Tyrel Datwyler <tyreld@linux.ibm.com> Cc: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, "Gautham R. Shenoy" <ego@linux.vnet.ibm.com> Subject: [PATCH v5 2/5] powerpc/idle: Store PURR snapshot in a per-cpu global variable Date: Tue, 7 Apr 2020 14:17:40 +0530 [thread overview] Message-ID: <1586249263-14048-3-git-send-email-ego@linux.vnet.ibm.com> (raw) In-Reply-To: <1586249263-14048-1-git-send-email-ego@linux.vnet.ibm.com> From: "Gautham R. Shenoy" <ego@linux.vnet.ibm.com> Currently when CPU goes idle, we take a snapshot of PURR via pseries_idle_prolog() which is used at the CPU idle exit to compute the idle PURR cycles via the function pseries_idle_epilog(). Thus, the value of idle PURR cycle thus read before pseries_idle_prolog() and after pseries_idle_epilog() is always correct. However, if we were to read the idle PURR cycles from an interrupt context between pseries_idle_prolog() and pseries_idle_epilog() (this will be done in a future patch), then, the value of the idle PURR thus read will not include the cycles spent in the most recent idle period. Thus, in that interrupt context, we will need access to the snapshot of the PURR before going idle, in order to compute the idle PURR cycles for the latest idle duration. In this patch, we save the snapshot of PURR in pseries_idle_prolog() in a per-cpu variable, instead of on the stack, so that it can be accessed from an interrupt context. Signed-off-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com> --- arch/powerpc/include/asm/idle.h | 31 ++++++++++++++++++++++--------- arch/powerpc/platforms/pseries/setup.c | 7 +++---- drivers/cpuidle/cpuidle-pseries.c | 15 ++++++--------- 3 files changed, 31 insertions(+), 22 deletions(-) diff --git a/arch/powerpc/include/asm/idle.h b/arch/powerpc/include/asm/idle.h index 32064a4c..b90d75a 100644 --- a/arch/powerpc/include/asm/idle.h +++ b/arch/powerpc/include/asm/idle.h @@ -5,10 +5,27 @@ #include <asm/paca.h> #ifdef CONFIG_PPC_PSERIES -static inline void pseries_idle_prolog(unsigned long *in_purr) +DECLARE_PER_CPU(u64, idle_entry_purr_snap); + +static inline void snapshot_purr_idle_entry(void) +{ + *this_cpu_ptr(&idle_entry_purr_snap) = mfspr(SPRN_PURR); +} + +static inline void update_idle_purr_accounting(void) +{ + u64 wait_cycles; + u64 in_purr = *this_cpu_ptr(&idle_entry_purr_snap); + + wait_cycles = be64_to_cpu(get_lppaca()->wait_state_cycles); + wait_cycles += mfspr(SPRN_PURR) - in_purr; + get_lppaca()->wait_state_cycles = cpu_to_be64(wait_cycles); +} + +static inline void pseries_idle_prolog(void) { ppc64_runlatch_off(); - *in_purr = mfspr(SPRN_PURR); + snapshot_purr_idle_entry(); /* * Indicate to the HV that we are idle. Now would be * a good time to find other work to dispatch. @@ -16,16 +33,12 @@ static inline void pseries_idle_prolog(unsigned long *in_purr) get_lppaca()->idle = 1; } -static inline void pseries_idle_epilog(unsigned long in_purr) +static inline void pseries_idle_epilog(void) { - u64 wait_cycles; - - wait_cycles = be64_to_cpu(get_lppaca()->wait_state_cycles); - wait_cycles += mfspr(SPRN_PURR) - in_purr; - get_lppaca()->wait_state_cycles = cpu_to_be64(wait_cycles); + update_idle_purr_accounting(); get_lppaca()->idle = 0; - ppc64_runlatch_on(); } + #endif /* CONFIG_PPC_PSERIES */ #endif diff --git a/arch/powerpc/platforms/pseries/setup.c b/arch/powerpc/platforms/pseries/setup.c index 2f53e6b..4905c96 100644 --- a/arch/powerpc/platforms/pseries/setup.c +++ b/arch/powerpc/platforms/pseries/setup.c @@ -318,10 +318,9 @@ static int alloc_dispatch_log_kmem_cache(void) } machine_early_initcall(pseries, alloc_dispatch_log_kmem_cache); +DEFINE_PER_CPU(u64, idle_entry_purr_snap); static void pseries_lpar_idle(void) { - unsigned long in_purr; - /* * Default handler to go into low thread priority and possibly * low power mode by ceding processor to hypervisor @@ -331,7 +330,7 @@ static void pseries_lpar_idle(void) return; /* Indicate to hypervisor that we are idle. */ - pseries_idle_prolog(&in_purr); + pseries_idle_prolog(); /* * Yield the processor to the hypervisor. We return if @@ -342,7 +341,7 @@ static void pseries_lpar_idle(void) */ cede_processor(); - pseries_idle_epilog(in_purr); + pseries_idle_epilog(); } /* diff --git a/drivers/cpuidle/cpuidle-pseries.c b/drivers/cpuidle/cpuidle-pseries.c index 46d5e05..6513ef2 100644 --- a/drivers/cpuidle/cpuidle-pseries.c +++ b/drivers/cpuidle/cpuidle-pseries.c @@ -36,12 +36,11 @@ static int snooze_loop(struct cpuidle_device *dev, struct cpuidle_driver *drv, int index) { - unsigned long in_purr; u64 snooze_exit_time; set_thread_flag(TIF_POLLING_NRFLAG); - pseries_idle_prolog(&in_purr); + pseries_idle_prolog(); local_irq_enable(); snooze_exit_time = get_tb() + snooze_timeout; @@ -65,7 +64,7 @@ static int snooze_loop(struct cpuidle_device *dev, local_irq_disable(); - pseries_idle_epilog(in_purr); + pseries_idle_epilog(); return index; } @@ -91,9 +90,8 @@ static int dedicated_cede_loop(struct cpuidle_device *dev, struct cpuidle_driver *drv, int index) { - unsigned long in_purr; - pseries_idle_prolog(&in_purr); + pseries_idle_prolog(); get_lppaca()->donate_dedicated_cpu = 1; HMT_medium(); @@ -102,7 +100,7 @@ static int dedicated_cede_loop(struct cpuidle_device *dev, local_irq_disable(); get_lppaca()->donate_dedicated_cpu = 0; - pseries_idle_epilog(in_purr); + pseries_idle_epilog(); return index; } @@ -111,9 +109,8 @@ static int shared_cede_loop(struct cpuidle_device *dev, struct cpuidle_driver *drv, int index) { - unsigned long in_purr; - pseries_idle_prolog(&in_purr); + pseries_idle_prolog(); /* * Yield the processor to the hypervisor. We return if @@ -125,7 +122,7 @@ static int shared_cede_loop(struct cpuidle_device *dev, check_and_cede_processor(); local_irq_disable(); - pseries_idle_epilog(in_purr); + pseries_idle_epilog(); return index; } -- 1.9.4
WARNING: multiple messages have this Message-ID (diff)
From: "Gautham R. Shenoy" <ego@linux.vnet.ibm.com> To: Nathan Lynch <nathanl@linux.ibm.com>, Michael Ellerman <mpe@ellerman.id.au>, Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>, Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>, "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com>, Tyrel Datwyler <tyreld@linux.ibm.com> Cc: "Gautham R. Shenoy" <ego@linux.vnet.ibm.com>, linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org Subject: [PATCH v5 2/5] powerpc/idle: Store PURR snapshot in a per-cpu global variable Date: Tue, 7 Apr 2020 14:17:40 +0530 [thread overview] Message-ID: <1586249263-14048-3-git-send-email-ego@linux.vnet.ibm.com> (raw) In-Reply-To: <1586249263-14048-1-git-send-email-ego@linux.vnet.ibm.com> From: "Gautham R. Shenoy" <ego@linux.vnet.ibm.com> Currently when CPU goes idle, we take a snapshot of PURR via pseries_idle_prolog() which is used at the CPU idle exit to compute the idle PURR cycles via the function pseries_idle_epilog(). Thus, the value of idle PURR cycle thus read before pseries_idle_prolog() and after pseries_idle_epilog() is always correct. However, if we were to read the idle PURR cycles from an interrupt context between pseries_idle_prolog() and pseries_idle_epilog() (this will be done in a future patch), then, the value of the idle PURR thus read will not include the cycles spent in the most recent idle period. Thus, in that interrupt context, we will need access to the snapshot of the PURR before going idle, in order to compute the idle PURR cycles for the latest idle duration. In this patch, we save the snapshot of PURR in pseries_idle_prolog() in a per-cpu variable, instead of on the stack, so that it can be accessed from an interrupt context. Signed-off-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com> --- arch/powerpc/include/asm/idle.h | 31 ++++++++++++++++++++++--------- arch/powerpc/platforms/pseries/setup.c | 7 +++---- drivers/cpuidle/cpuidle-pseries.c | 15 ++++++--------- 3 files changed, 31 insertions(+), 22 deletions(-) diff --git a/arch/powerpc/include/asm/idle.h b/arch/powerpc/include/asm/idle.h index 32064a4c..b90d75a 100644 --- a/arch/powerpc/include/asm/idle.h +++ b/arch/powerpc/include/asm/idle.h @@ -5,10 +5,27 @@ #include <asm/paca.h> #ifdef CONFIG_PPC_PSERIES -static inline void pseries_idle_prolog(unsigned long *in_purr) +DECLARE_PER_CPU(u64, idle_entry_purr_snap); + +static inline void snapshot_purr_idle_entry(void) +{ + *this_cpu_ptr(&idle_entry_purr_snap) = mfspr(SPRN_PURR); +} + +static inline void update_idle_purr_accounting(void) +{ + u64 wait_cycles; + u64 in_purr = *this_cpu_ptr(&idle_entry_purr_snap); + + wait_cycles = be64_to_cpu(get_lppaca()->wait_state_cycles); + wait_cycles += mfspr(SPRN_PURR) - in_purr; + get_lppaca()->wait_state_cycles = cpu_to_be64(wait_cycles); +} + +static inline void pseries_idle_prolog(void) { ppc64_runlatch_off(); - *in_purr = mfspr(SPRN_PURR); + snapshot_purr_idle_entry(); /* * Indicate to the HV that we are idle. Now would be * a good time to find other work to dispatch. @@ -16,16 +33,12 @@ static inline void pseries_idle_prolog(unsigned long *in_purr) get_lppaca()->idle = 1; } -static inline void pseries_idle_epilog(unsigned long in_purr) +static inline void pseries_idle_epilog(void) { - u64 wait_cycles; - - wait_cycles = be64_to_cpu(get_lppaca()->wait_state_cycles); - wait_cycles += mfspr(SPRN_PURR) - in_purr; - get_lppaca()->wait_state_cycles = cpu_to_be64(wait_cycles); + update_idle_purr_accounting(); get_lppaca()->idle = 0; - ppc64_runlatch_on(); } + #endif /* CONFIG_PPC_PSERIES */ #endif diff --git a/arch/powerpc/platforms/pseries/setup.c b/arch/powerpc/platforms/pseries/setup.c index 2f53e6b..4905c96 100644 --- a/arch/powerpc/platforms/pseries/setup.c +++ b/arch/powerpc/platforms/pseries/setup.c @@ -318,10 +318,9 @@ static int alloc_dispatch_log_kmem_cache(void) } machine_early_initcall(pseries, alloc_dispatch_log_kmem_cache); +DEFINE_PER_CPU(u64, idle_entry_purr_snap); static void pseries_lpar_idle(void) { - unsigned long in_purr; - /* * Default handler to go into low thread priority and possibly * low power mode by ceding processor to hypervisor @@ -331,7 +330,7 @@ static void pseries_lpar_idle(void) return; /* Indicate to hypervisor that we are idle. */ - pseries_idle_prolog(&in_purr); + pseries_idle_prolog(); /* * Yield the processor to the hypervisor. We return if @@ -342,7 +341,7 @@ static void pseries_lpar_idle(void) */ cede_processor(); - pseries_idle_epilog(in_purr); + pseries_idle_epilog(); } /* diff --git a/drivers/cpuidle/cpuidle-pseries.c b/drivers/cpuidle/cpuidle-pseries.c index 46d5e05..6513ef2 100644 --- a/drivers/cpuidle/cpuidle-pseries.c +++ b/drivers/cpuidle/cpuidle-pseries.c @@ -36,12 +36,11 @@ static int snooze_loop(struct cpuidle_device *dev, struct cpuidle_driver *drv, int index) { - unsigned long in_purr; u64 snooze_exit_time; set_thread_flag(TIF_POLLING_NRFLAG); - pseries_idle_prolog(&in_purr); + pseries_idle_prolog(); local_irq_enable(); snooze_exit_time = get_tb() + snooze_timeout; @@ -65,7 +64,7 @@ static int snooze_loop(struct cpuidle_device *dev, local_irq_disable(); - pseries_idle_epilog(in_purr); + pseries_idle_epilog(); return index; } @@ -91,9 +90,8 @@ static int dedicated_cede_loop(struct cpuidle_device *dev, struct cpuidle_driver *drv, int index) { - unsigned long in_purr; - pseries_idle_prolog(&in_purr); + pseries_idle_prolog(); get_lppaca()->donate_dedicated_cpu = 1; HMT_medium(); @@ -102,7 +100,7 @@ static int dedicated_cede_loop(struct cpuidle_device *dev, local_irq_disable(); get_lppaca()->donate_dedicated_cpu = 0; - pseries_idle_epilog(in_purr); + pseries_idle_epilog(); return index; } @@ -111,9 +109,8 @@ static int shared_cede_loop(struct cpuidle_device *dev, struct cpuidle_driver *drv, int index) { - unsigned long in_purr; - pseries_idle_prolog(&in_purr); + pseries_idle_prolog(); /* * Yield the processor to the hypervisor. We return if @@ -125,7 +122,7 @@ static int shared_cede_loop(struct cpuidle_device *dev, check_and_cede_processor(); local_irq_disable(); - pseries_idle_epilog(in_purr); + pseries_idle_epilog(); return index; } -- 1.9.4
next prev parent reply other threads:[~2020-04-07 8:48 UTC|newest] Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-04-07 8:47 [PATCH v5 0/5] Track and expose idle PURR and SPURR ticks Gautham R. Shenoy 2020-04-07 8:47 ` Gautham R. Shenoy 2020-04-07 8:47 ` [PATCH v5 1/5] powerpc: Move idle_loop_prolog()/epilog() functions to header file Gautham R. Shenoy 2020-04-07 8:47 ` Gautham R. Shenoy 2020-05-06 2:51 ` Michael Ellerman 2020-04-07 8:47 ` Gautham R. Shenoy [this message] 2020-04-07 8:47 ` [PATCH v5 2/5] powerpc/idle: Store PURR snapshot in a per-cpu global variable Gautham R. Shenoy 2020-04-07 8:47 ` [PATCH v5 3/5] powerpc/pseries: Account for SPURR ticks on idle CPUs Gautham R. Shenoy 2020-04-07 8:47 ` Gautham R. Shenoy 2020-04-07 8:47 ` [PATCH v5 4/5] powerpc/sysfs: Show idle_purr and idle_spurr for every CPU Gautham R. Shenoy 2020-04-07 8:47 ` Gautham R. Shenoy 2020-04-07 8:47 ` [PATCH v5 5/5] Documentation: Document sysfs interfaces purr, spurr, idle_purr, idle_spurr Gautham R. Shenoy 2020-04-07 8:47 ` Gautham R. Shenoy 2020-04-07 9:05 ` [PATCH v5 0/5] Track and expose idle PURR and SPURR ticks Naveen N. Rao 2020-04-07 9:05 ` Naveen N. Rao 2020-04-07 11:24 ` Kamalesh Babulal 2020-04-20 22:46 ` Tyrel Datwyler 2020-04-23 10:02 ` Gautham R Shenoy 2020-04-23 10:02 ` Gautham R Shenoy 2020-04-30 2:34 ` Michael Ellerman 2020-04-30 2:34 ` Michael Ellerman 2020-04-30 4:16 ` Gautham R Shenoy 2020-04-30 4:16 ` Gautham R Shenoy 2020-05-01 5:50 ` Gautham R Shenoy 2020-05-01 5:50 ` Gautham R Shenoy 2020-04-21 13:30 ` Nathan Lynch 2020-04-21 13:30 ` Nathan Lynch
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