* Re: [PATCH] sched/fair: Use sched_energy_enabled()
2026-03-27 13:20 [PATCH] sched/fair: Use sched_energy_enabled() Vincent Guittot
@ 2026-03-27 13:54 ` Shrikanth Hegde
2026-03-27 16:18 ` K Prateek Nayak
2026-04-03 12:30 ` [tip: sched/core] " tip-bot2 for Vincent Guittot
2 siblings, 0 replies; 7+ messages in thread
From: Shrikanth Hegde @ 2026-03-27 13:54 UTC (permalink / raw)
To: Vincent Guittot
Cc: mingo, peterz, juri.lelli, dietmar.eggemann, rostedt, bsegall,
mgorman, vschneid, kprateek.nayak, linux-kernel
On 3/27/26 6:50 PM, Vincent Guittot wrote:
> Use helper sched_energy_enabled() everywhere we want to test if EAS is
> enabled instead of mixing sched_energy_enabled() and direct call to
> static_branch_unlikely().
>
> No functional change
>
Makes sense.
> Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
> ---
> kernel/sched/topology.c | 9 ++++-----
> 1 file changed, 4 insertions(+), 5 deletions(-)
>
> diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c
> index 43150591914b..5847b83d9d55 100644
> --- a/kernel/sched/topology.c
> +++ b/kernel/sched/topology.c
> @@ -273,7 +273,7 @@ void rebuild_sched_domains_energy(void)
> static int sched_energy_aware_handler(const struct ctl_table *table, int write,
> void *buffer, size_t *lenp, loff_t *ppos)
> {
> - int ret, state;
> + int ret;
>
> if (write && !capable(CAP_SYS_ADMIN))
> return -EPERM;
> @@ -289,8 +289,7 @@ static int sched_energy_aware_handler(const struct ctl_table *table, int write,
>
> ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
> if (!ret && write) {
> - state = static_branch_unlikely(&sched_energy_present);
> - if (state != sysctl_sched_energy_aware)
> + if (sysctl_sched_energy_aware != sched_energy_enabled())
> rebuild_sched_domains_energy();
> }
>
> @@ -388,11 +387,11 @@ static void destroy_perf_domain_rcu(struct rcu_head *rp)
>
> static void sched_energy_set(bool has_eas)
> {
> - if (!has_eas && static_branch_unlikely(&sched_energy_present)) {
> + if (!has_eas && sched_energy_enabled()) {
> if (sched_debug())
> pr_info("%s: stopping EAS\n", __func__);
> static_branch_disable_cpuslocked(&sched_energy_present);
> - } else if (has_eas && !static_branch_unlikely(&sched_energy_present)) {
> + } else if (has_eas && !sched_energy_enabled()) {
> if (sched_debug())
> pr_info("%s: starting EAS\n", __func__);
> static_branch_enable_cpuslocked(&sched_energy_present);
Acked-by: Shrikanth Hegde <sshegde@linux.ibm.com>
^ permalink raw reply [flat|nested] 7+ messages in thread* Re: [PATCH] sched/fair: Use sched_energy_enabled()
2026-03-27 13:20 [PATCH] sched/fair: Use sched_energy_enabled() Vincent Guittot
2026-03-27 13:54 ` Shrikanth Hegde
@ 2026-03-27 16:18 ` K Prateek Nayak
2026-03-27 16:32 ` Vincent Guittot
2026-04-03 12:30 ` [tip: sched/core] " tip-bot2 for Vincent Guittot
2 siblings, 1 reply; 7+ messages in thread
From: K Prateek Nayak @ 2026-03-27 16:18 UTC (permalink / raw)
To: Vincent Guittot, mingo, peterz, juri.lelli, dietmar.eggemann,
rostedt, bsegall, mgorman, vschneid, linux-kernel
Hello Vincent,
On 3/27/2026 6:50 PM, Vincent Guittot wrote:
> Use helper sched_energy_enabled() everywhere we want to test if EAS is
> enabled instead of mixing sched_energy_enabled() and direct call to
> static_branch_unlikely().
>
> No functional change
>
> Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Feel free to include:
Reviewed-by: K Prateek Nayak <kprateek.nayak@amd.com>
Tested-by: K Prateek Nayak <kprateek.nayak@amd.com>
> ---
> kernel/sched/topology.c | 9 ++++-----
> 1 file changed, 4 insertions(+), 5 deletions(-)
>
> diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c
> index 43150591914b..5847b83d9d55 100644
> --- a/kernel/sched/topology.c
> +++ b/kernel/sched/topology.c
> @@ -273,7 +273,7 @@ void rebuild_sched_domains_energy(void)
> static int sched_energy_aware_handler(const struct ctl_table *table, int write,
> void *buffer, size_t *lenp, loff_t *ppos)
> {
> - int ret, state;
> + int ret;
>
> if (write && !capable(CAP_SYS_ADMIN))
> return -EPERM;
> @@ -289,8 +289,7 @@ static int sched_energy_aware_handler(const struct ctl_table *table, int write,
>
> ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
> if (!ret && write) {
> - state = static_branch_unlikely(&sched_energy_present);
> - if (state != sysctl_sched_energy_aware)
> + if (sysctl_sched_energy_aware != sched_energy_enabled())
Quick tangential question:
Since "sysctl_sched_energy_aware" is initialized to "1", if
build_perf_domains() returns false at boot, sysctl_sched_energy_aware
and sched_energy_enabled() will go out of sync and reading
"/proc/sys/kernel/sched_energy_aware" will still show "1" despite EAS
being disabled.
Is that okay?
Some sysctls like numa_balancing will show 0 if disabled (by user or
due to lack of NUMA) reflecting the real state of system. Should
sched_energy_aware do the same?
> rebuild_sched_domains_energy();
> }
>
--
Thanks and Regards,
Prateek
^ permalink raw reply [flat|nested] 7+ messages in thread* Re: [PATCH] sched/fair: Use sched_energy_enabled()
2026-03-27 16:18 ` K Prateek Nayak
@ 2026-03-27 16:32 ` Vincent Guittot
2026-03-27 17:09 ` K Prateek Nayak
2026-03-27 17:10 ` Dietmar Eggemann
0 siblings, 2 replies; 7+ messages in thread
From: Vincent Guittot @ 2026-03-27 16:32 UTC (permalink / raw)
To: K Prateek Nayak
Cc: mingo, peterz, juri.lelli, dietmar.eggemann, rostedt, bsegall,
mgorman, vschneid, linux-kernel
On Fri, 27 Mar 2026 at 17:18, K Prateek Nayak <kprateek.nayak@amd.com> wrote:
>
> Hello Vincent,
>
> On 3/27/2026 6:50 PM, Vincent Guittot wrote:
> > Use helper sched_energy_enabled() everywhere we want to test if EAS is
> > enabled instead of mixing sched_energy_enabled() and direct call to
> > static_branch_unlikely().
> >
> > No functional change
> >
> > Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
>
> Feel free to include:
>
> Reviewed-by: K Prateek Nayak <kprateek.nayak@amd.com>
> Tested-by: K Prateek Nayak <kprateek.nayak@amd.com>
>
> > ---
> > kernel/sched/topology.c | 9 ++++-----
> > 1 file changed, 4 insertions(+), 5 deletions(-)
> >
> > diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c
> > index 43150591914b..5847b83d9d55 100644
> > --- a/kernel/sched/topology.c
> > +++ b/kernel/sched/topology.c
> > @@ -273,7 +273,7 @@ void rebuild_sched_domains_energy(void)
> > static int sched_energy_aware_handler(const struct ctl_table *table, int write,
> > void *buffer, size_t *lenp, loff_t *ppos)
> > {
> > - int ret, state;
> > + int ret;
> >
> > if (write && !capable(CAP_SYS_ADMIN))
> > return -EPERM;
> > @@ -289,8 +289,7 @@ static int sched_energy_aware_handler(const struct ctl_table *table, int write,
> >
> > ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
> > if (!ret && write) {
> > - state = static_branch_unlikely(&sched_energy_present);
> > - if (state != sysctl_sched_energy_aware)
> > + if (sysctl_sched_energy_aware != sched_energy_enabled())
>
> Quick tangential question:
>
> Since "sysctl_sched_energy_aware" is initialized to "1", if
> build_perf_domains() returns false at boot, sysctl_sched_energy_aware
> and sched_energy_enabled() will go out of sync and reading
> "/proc/sys/kernel/sched_energy_aware" will still show "1" despite EAS
> being disabled.
>
> Is that okay?
Isn't the call to sched_is_eas_possible() there to prevent this case ?
>
> Some sysctls like numa_balancing will show 0 if disabled (by user or
> due to lack of NUMA) reflecting the real state of system. Should
> sched_energy_aware do the same?
>
> > rebuild_sched_domains_energy();
> > }
> >
> --
> Thanks and Regards,
> Prateek
^ permalink raw reply [flat|nested] 7+ messages in thread* Re: [PATCH] sched/fair: Use sched_energy_enabled()
2026-03-27 16:32 ` Vincent Guittot
@ 2026-03-27 17:09 ` K Prateek Nayak
2026-03-27 17:10 ` Dietmar Eggemann
1 sibling, 0 replies; 7+ messages in thread
From: K Prateek Nayak @ 2026-03-27 17:09 UTC (permalink / raw)
To: Vincent Guittot
Cc: mingo, peterz, juri.lelli, dietmar.eggemann, rostedt, bsegall,
mgorman, vschneid, linux-kernel
Hello Vincent,
On 3/27/2026 10:02 PM, Vincent Guittot wrote:
>>> + if (sysctl_sched_energy_aware != sched_energy_enabled())
>>
>> Quick tangential question:
>>
>> Since "sysctl_sched_energy_aware" is initialized to "1", if
>> build_perf_domains() returns false at boot, sysctl_sched_energy_aware
>> and sched_energy_enabled() will go out of sync and reading
>> "/proc/sys/kernel/sched_energy_aware" will still show "1" despite EAS
>> being disabled.
>>
>> Is that okay?
>
> Isn't the call to sched_is_eas_possible() there to prevent this case ?
Ah! pd_init() can never fail (expect for -ENOMEME)
I somehow thought there was more to it. Sorry for the noise.
>>
>> Some sysctls like numa_balancing will show 0 if disabled (by user or
>> due to lack of NUMA) reflecting the real state of system. Should
>> sched_energy_aware do the same?
--
Thanks and Regards,
Prateek
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH] sched/fair: Use sched_energy_enabled()
2026-03-27 16:32 ` Vincent Guittot
2026-03-27 17:09 ` K Prateek Nayak
@ 2026-03-27 17:10 ` Dietmar Eggemann
1 sibling, 0 replies; 7+ messages in thread
From: Dietmar Eggemann @ 2026-03-27 17:10 UTC (permalink / raw)
To: Vincent Guittot, K Prateek Nayak
Cc: mingo, peterz, juri.lelli, rostedt, bsegall, mgorman, vschneid,
linux-kernel
On 27.03.26 17:32, Vincent Guittot wrote:
> On Fri, 27 Mar 2026 at 17:18, K Prateek Nayak <kprateek.nayak@amd.com> wrote:
>>
>> Hello Vincent,
>>
>> On 3/27/2026 6:50 PM, Vincent Guittot wrote:
>>> Use helper sched_energy_enabled() everywhere we want to test if EAS is
>>> enabled instead of mixing sched_energy_enabled() and direct call to
>>> static_branch_unlikely().
>>>
>>> No functional change
>>>
>>> Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
>>
>> Feel free to include:
>>
>> Reviewed-by: K Prateek Nayak <kprateek.nayak@amd.com>
>> Tested-by: K Prateek Nayak <kprateek.nayak@amd.com>
>>
>>> ---
>>> kernel/sched/topology.c | 9 ++++-----
>>> 1 file changed, 4 insertions(+), 5 deletions(-)
>>>
>>> diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c
>>> index 43150591914b..5847b83d9d55 100644
>>> --- a/kernel/sched/topology.c
>>> +++ b/kernel/sched/topology.c
>>> @@ -273,7 +273,7 @@ void rebuild_sched_domains_energy(void)
>>> static int sched_energy_aware_handler(const struct ctl_table *table, int write,
>>> void *buffer, size_t *lenp, loff_t *ppos)
>>> {
>>> - int ret, state;
>>> + int ret;
>>>
>>> if (write && !capable(CAP_SYS_ADMIN))
>>> return -EPERM;
>>> @@ -289,8 +289,7 @@ static int sched_energy_aware_handler(const struct ctl_table *table, int write,
>>>
>>> ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
>>> if (!ret && write) {
>>> - state = static_branch_unlikely(&sched_energy_present);
>>> - if (state != sysctl_sched_energy_aware)
>>> + if (sysctl_sched_energy_aware != sched_energy_enabled())
>>
>> Quick tangential question:
>>
>> Since "sysctl_sched_energy_aware" is initialized to "1", if
>> build_perf_domains() returns false at boot, sysctl_sched_energy_aware
>> and sched_energy_enabled() will go out of sync and reading
>> "/proc/sys/kernel/sched_energy_aware" will still show "1" despite EAS
>> being disabled.
>>
>> Is that okay?
>
> Isn't the call to sched_is_eas_possible() there to prevent this case ?
Yes, I think so:
300 static const struct ctl_table sched_energy_aware_sysctls[] = {
...
302 .procname = "sched_energy_aware",
...
306 .proc_handler = sched_energy_aware_handler,
273 sched_energy_aware_handler()
...
281 if (!sched_is_eas_possible(cpu_active_mask)) { <-- !!!
282 if (write) {
283 return -EOPNOTSUPP;
284 } else {
285 *lenp = 0;
286 return 0;
287 }
...
# cat /proc/sys/kernel/sched_energy_aware
1
# ./set_cpufreq_ondemand.sh
cat /proc/sys/kernel/sched_energy_aware
[ 391.591167] rd 0-5: Checking EAS: cpufreq is not ready
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
[...]
^ permalink raw reply [flat|nested] 7+ messages in thread
* [tip: sched/core] sched/fair: Use sched_energy_enabled()
2026-03-27 13:20 [PATCH] sched/fair: Use sched_energy_enabled() Vincent Guittot
2026-03-27 13:54 ` Shrikanth Hegde
2026-03-27 16:18 ` K Prateek Nayak
@ 2026-04-03 12:30 ` tip-bot2 for Vincent Guittot
2 siblings, 0 replies; 7+ messages in thread
From: tip-bot2 for Vincent Guittot @ 2026-04-03 12:30 UTC (permalink / raw)
To: linux-tip-commits
Cc: Vincent Guittot, Peter Zijlstra (Intel), x86, linux-kernel
The following commit has been merged into the sched/core branch of tip:
Commit-ID: 2d4cc371baa5881da45120a65d264a59b486f486
Gitweb: https://git.kernel.org/tip/2d4cc371baa5881da45120a65d264a59b486f486
Author: Vincent Guittot <vincent.guittot@linaro.org>
AuthorDate: Fri, 27 Mar 2026 14:20:13 +01:00
Committer: Peter Zijlstra <peterz@infradead.org>
CommitterDate: Fri, 03 Apr 2026 14:23:41 +02:00
sched/fair: Use sched_energy_enabled()
Use helper sched_energy_enabled() everywhere we want to test if EAS is
enabled instead of mixing sched_energy_enabled() and direct call to
static_branch_unlikely().
No functional change
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260327132013.2800517-1-vincent.guittot@linaro.org
---
kernel/sched/topology.c | 9 ++++-----
1 file changed, 4 insertions(+), 5 deletions(-)
diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c
index 4315059..5847b83 100644
--- a/kernel/sched/topology.c
+++ b/kernel/sched/topology.c
@@ -273,7 +273,7 @@ void rebuild_sched_domains_energy(void)
static int sched_energy_aware_handler(const struct ctl_table *table, int write,
void *buffer, size_t *lenp, loff_t *ppos)
{
- int ret, state;
+ int ret;
if (write && !capable(CAP_SYS_ADMIN))
return -EPERM;
@@ -289,8 +289,7 @@ static int sched_energy_aware_handler(const struct ctl_table *table, int write,
ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
if (!ret && write) {
- state = static_branch_unlikely(&sched_energy_present);
- if (state != sysctl_sched_energy_aware)
+ if (sysctl_sched_energy_aware != sched_energy_enabled())
rebuild_sched_domains_energy();
}
@@ -388,11 +387,11 @@ static void destroy_perf_domain_rcu(struct rcu_head *rp)
static void sched_energy_set(bool has_eas)
{
- if (!has_eas && static_branch_unlikely(&sched_energy_present)) {
+ if (!has_eas && sched_energy_enabled()) {
if (sched_debug())
pr_info("%s: stopping EAS\n", __func__);
static_branch_disable_cpuslocked(&sched_energy_present);
- } else if (has_eas && !static_branch_unlikely(&sched_energy_present)) {
+ } else if (has_eas && !sched_energy_enabled()) {
if (sched_debug())
pr_info("%s: starting EAS\n", __func__);
static_branch_enable_cpuslocked(&sched_energy_present);
^ permalink raw reply [flat|nested] 7+ messages in thread