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authorGautham R. Shenoy <ego@linux.vnet.ibm.com>2020-07-30 08:32:55 +0300
committerMichael Ellerman <mpe@ellerman.id.au>2020-07-30 15:53:50 +0300
commit3af0ada7dd98c6da35c1fd7f107af3b9aa5e904c (patch)
tree5cc7533357bebcef6c74b51185cd230cec6e8d81 /drivers/cpuidle
parentdfa03fff86027e58c8dba5c03ae68150d4e513ad (diff)
downloadlinux-3af0ada7dd98c6da35c1fd7f107af3b9aa5e904c.tar.xz
cpuidle: pseries: Set the latency-hint before entering CEDE
As per the PAPR, each H_CEDE call is associated with a latency-hint to be passed in the VPA field "cede_latency_hint". The CEDE states that we were implicitly entering so far is CEDE with latency-hint = 0. This patch explicitly sets the latency hint corresponding to the CEDE state that we are currently entering. While at it, we save the previous hint, to be restored once we wakeup from CEDE. This will be required in the future when we expose extended-cede states through the cpuidle framework, where each of them will have a different cede-latency hint. Signed-off-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com> [mpe: Make cede_latency_hint static] Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/1596087177-30329-2-git-send-email-ego@linux.vnet.ibm.com
Diffstat (limited to 'drivers/cpuidle')
-rw-r--r--drivers/cpuidle/cpuidle-pseries.c12
1 files changed, 10 insertions, 2 deletions
diff --git a/drivers/cpuidle/cpuidle-pseries.c b/drivers/cpuidle/cpuidle-pseries.c
index 3e058ad2bb51..31c8e51162b2 100644
--- a/drivers/cpuidle/cpuidle-pseries.c
+++ b/drivers/cpuidle/cpuidle-pseries.c
@@ -86,19 +86,27 @@ static void check_and_cede_processor(void)
}
}
+#define NR_DEDICATED_STATES 2 /* snooze, CEDE */
+
+static u8 cede_latency_hint[NR_DEDICATED_STATES];
+
static int dedicated_cede_loop(struct cpuidle_device *dev,
struct cpuidle_driver *drv,
int index)
{
+ u8 old_latency_hint;
pseries_idle_prolog();
get_lppaca()->donate_dedicated_cpu = 1;
+ old_latency_hint = get_lppaca()->cede_latency_hint;
+ get_lppaca()->cede_latency_hint = cede_latency_hint[index];
HMT_medium();
check_and_cede_processor();
local_irq_disable();
get_lppaca()->donate_dedicated_cpu = 0;
+ get_lppaca()->cede_latency_hint = old_latency_hint;
pseries_idle_epilog();
@@ -130,7 +138,7 @@ static int shared_cede_loop(struct cpuidle_device *dev,
/*
* States for dedicated partition case.
*/
-static struct cpuidle_state dedicated_states[] = {
+static struct cpuidle_state dedicated_states[NR_DEDICATED_STATES] = {
{ /* Snooze */
.name = "snooze",
.desc = "snooze",
@@ -233,7 +241,7 @@ static int pseries_idle_probe(void)
max_idle_state = ARRAY_SIZE(shared_states);
} else {
cpuidle_state_table = dedicated_states;
- max_idle_state = ARRAY_SIZE(dedicated_states);
+ max_idle_state = NR_DEDICATED_STATES;
}
} else
return -ENODEV;