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authorGautham R. Shenoy <ego@linux.vnet.ibm.com>2020-04-07 14:17:40 +0530
committerMichael Ellerman <mpe@ellerman.id.au>2020-04-30 12:35:26 +1000
commitc4019198cfa81224d32846915cd401e981f81b81 (patch)
tree994b84d8582d386910ae90f055415899b8bd367f /drivers/cpuidle
parente4a884cc28fa3f5d8b81de46998ffe29b4ad169e (diff)
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 <ego@linux.vnet.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/1586249263-14048-3-git-send-email-ego@linux.vnet.ibm.com
Diffstat (limited to 'drivers/cpuidle')
-rw-r--r--drivers/cpuidle/cpuidle-pseries.c15
1 files changed, 6 insertions, 9 deletions
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;
}