From e4a884cc28fa3f5d8b81de46998ffe29b4ad169e Mon Sep 17 00:00:00 2001 From: "Gautham R. Shenoy" Date: Tue, 7 Apr 2020 14:17:39 +0530 Subject: powerpc: Move idle_loop_prolog()/epilog() functions to header file Currently prior to entering an idle state on a Linux Guest, the pseries cpuidle driver implement an idle_loop_prolog() and idle_loop_epilog() functions which ensure that idle_purr is correctly computed, and the hypervisor is informed that the CPU cycles have been donated. These prolog and epilog functions are also required in the default idle call, i.e pseries_lpar_idle(). Hence move these accessor functions to a common header file and call them from pseries_lpar_idle(). Since the existing header files such as asm/processor.h have enough clutter, create a new header file asm/idle.h. Finally rename idle_loop_prolog() and idle_loop_epilog() to pseries_idle_prolog() and pseries_idle_epilog() as they are only relavent for on pseries guests. Signed-off-by: Gautham R. Shenoy Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/1586249263-14048-2-git-send-email-ego@linux.vnet.ibm.com --- drivers/cpuidle/cpuidle-pseries.c | 36 +++++++----------------------------- 1 file changed, 7 insertions(+), 29 deletions(-) (limited to 'drivers/cpuidle') diff --git a/drivers/cpuidle/cpuidle-pseries.c b/drivers/cpuidle/cpuidle-pseries.c index 74c247972bb3..46d5e05fcf97 100644 --- a/drivers/cpuidle/cpuidle-pseries.c +++ b/drivers/cpuidle/cpuidle-pseries.c @@ -19,6 +19,7 @@ #include #include #include +#include #include struct cpuidle_driver pseries_idle_driver = { @@ -31,29 +32,6 @@ static struct cpuidle_state *cpuidle_state_table __read_mostly; static u64 snooze_timeout __read_mostly; static bool snooze_timeout_en __read_mostly; -static inline void idle_loop_prolog(unsigned long *in_purr) -{ - ppc64_runlatch_off(); - *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; -} - -static inline void idle_loop_epilog(unsigned long in_purr) -{ - 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); - get_lppaca()->idle = 0; - - ppc64_runlatch_on(); -} - static int snooze_loop(struct cpuidle_device *dev, struct cpuidle_driver *drv, int index) @@ -63,7 +41,7 @@ static int snooze_loop(struct cpuidle_device *dev, set_thread_flag(TIF_POLLING_NRFLAG); - idle_loop_prolog(&in_purr); + pseries_idle_prolog(&in_purr); local_irq_enable(); snooze_exit_time = get_tb() + snooze_timeout; @@ -87,7 +65,7 @@ static int snooze_loop(struct cpuidle_device *dev, local_irq_disable(); - idle_loop_epilog(in_purr); + pseries_idle_epilog(in_purr); return index; } @@ -115,7 +93,7 @@ static int dedicated_cede_loop(struct cpuidle_device *dev, { unsigned long in_purr; - idle_loop_prolog(&in_purr); + pseries_idle_prolog(&in_purr); get_lppaca()->donate_dedicated_cpu = 1; HMT_medium(); @@ -124,7 +102,7 @@ static int dedicated_cede_loop(struct cpuidle_device *dev, local_irq_disable(); get_lppaca()->donate_dedicated_cpu = 0; - idle_loop_epilog(in_purr); + pseries_idle_epilog(in_purr); return index; } @@ -135,7 +113,7 @@ static int shared_cede_loop(struct cpuidle_device *dev, { unsigned long in_purr; - idle_loop_prolog(&in_purr); + pseries_idle_prolog(&in_purr); /* * Yield the processor to the hypervisor. We return if @@ -147,7 +125,7 @@ static int shared_cede_loop(struct cpuidle_device *dev, check_and_cede_processor(); local_irq_disable(); - idle_loop_epilog(in_purr); + pseries_idle_epilog(in_purr); return index; } -- cgit v1.2.3 From c4019198cfa81224d32846915cd401e981f81b81 Mon Sep 17 00:00:00 2001 From: "Gautham R. Shenoy" Date: Tue, 7 Apr 2020 14:17:40 +0530 Subject: powerpc/idle: Store PURR snapshot in a per-cpu global variable 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 Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/1586249263-14048-3-git-send-email-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(-) (limited to 'drivers/cpuidle') diff --git a/arch/powerpc/include/asm/idle.h b/arch/powerpc/include/asm/idle.h index 32064a4c0dd7..b90d75aa1f9e 100644 --- a/arch/powerpc/include/asm/idle.h +++ b/arch/powerpc/include/asm/idle.h @@ -5,10 +5,27 @@ #include #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 2f53e6b031a7..4905c965e111 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 46d5e05fcf97..6513ef2af66a 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; } -- cgit v1.2.3