[PATCH v2 0/4] arm_pmu: Add PERF_PMU_CAP_EXTENDED_HW_TYPE capability

[PATCH v2 0/4] arm_pmu: Add PERF_PMU_CAP_EXTENDED_HW_TYPE capability

[James Clark]

Changes since v1:

  * Removed "legacy" description of PERF_TYPE_HARDWARE and
    PERF_TYPE_HW_CACHE events
  * Shift down remaining capability bits instead of inserting
    /* Unused */ in the gap (last commit)

Applies to v6.5-rc3

---------------------

This came out of the discussion here [1]. It seems like we can get some
extra big.LITTLE stuff working pretty easily. The test issues mentioned
in the linked thread are actually fairly unrelated and I've fixed them
in a different set on the list.

After adding it in the first commit, the remaining ones tidy up a
related capability that doesn't do anything any more.

I've added a fixes tag for the commit where
PERF_PMU_CAP_EXTENDED_HW_TYPE was originally added because it probably
should have been added to the Arm PMU at the same time. It doesn't apply
cleanly that far back because another capability was added between then,
but the resolution is trivial.

Thanks
James

[1]: https://lore.kernel.org/linux-perf-users/CAP-5=fVkRc9=ySJ=fG-SQ8oAKmE_1mhHHzSASmGHUsda5Qy92A@mail.gmail.com/T/#t

James Clark (4):
  arm_pmu: Add PERF_PMU_CAP_EXTENDED_HW_TYPE capability
  perf/x86: Remove unused PERF_PMU_CAP_HETEROGENEOUS_CPUS capability
  arm_pmu: Remove unused PERF_PMU_CAP_HETEROGENEOUS_CPUS capability
  perf: Remove unused PERF_PMU_CAP_HETEROGENEOUS_CPUS capability

 arch/x86/events/core.c     |  1 -
 drivers/perf/arm_pmu.c     | 10 ++++++----
 include/linux/perf_event.h |  7 +++----
 3 files changed, 9 insertions(+), 9 deletions(-)

-- 
2.34.1

[PATCH v2 1/4] arm_pmu: Add PERF_PMU_CAP_EXTENDED_HW_TYPE capability

[James Clark]

This capability gives us the ability to open PERF_TYPE_HARDWARE and
PERF_TYPE_HW_CACHE events on a specific PMU for free. All the
implementation is contained in the Perf core and tool code so no change
to the Arm PMU driver is needed.

The following basic use case now results in Perf opening the event on
all PMUs rather than picking only one in an unpredictable way:

  $ perf stat -e cycles -- taskset --cpu-list 0,1 stress -c 2

   Performance counter stats for 'taskset --cpu-list 0,1 stress -c 2':

         963279620      armv8_cortex_a57/cycles/                (99.19%)
         752745657      armv8_cortex_a53/cycles/                (94.80%)

Fixes: 55bcf6ef314a ("perf: Extend PERF_TYPE_HARDWARE and PERF_TYPE_HW_CACHE")
Suggested-by: Ian Rogers <irogers@google.com>
Acked-by: Ian Rogers <irogers@google.com>
Signed-off-by: James Clark <james.clark@arm.com>
---
 drivers/perf/arm_pmu.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/perf/arm_pmu.c b/drivers/perf/arm_pmu.c
index f6ccb2cd4dfc..2e79201daa4a 100644
--- a/drivers/perf/arm_pmu.c
+++ b/drivers/perf/arm_pmu.c
@@ -880,8 +880,13 @@ struct arm_pmu *armpmu_alloc(void)
 		 * configuration (e.g. big.LITTLE). This is not an uncore PMU,
 		 * and we have taken ctx sharing into account (e.g. with our
 		 * pmu::filter callback and pmu::event_init group validation).
+		 *
+		 * PERF_PMU_CAP_EXTENDED_HW_TYPE is required to open
+		 * PERF_TYPE_HARDWARE and PERF_TYPE_HW_CACHE events on a
+		 * specific PMU.
 		 */
-		.capabilities	= PERF_PMU_CAP_HETEROGENEOUS_CPUS | PERF_PMU_CAP_EXTENDED_REGS,
+		.capabilities	= PERF_PMU_CAP_HETEROGENEOUS_CPUS | PERF_PMU_CAP_EXTENDED_REGS |
+				  PERF_PMU_CAP_EXTENDED_HW_TYPE,
 	};
 
 	pmu->attr_groups[ARMPMU_ATTR_GROUP_COMMON] =
-- 
2.34.1

Re: [PATCH v2 1/4] arm_pmu: Add PERF_PMU_CAP_EXTENDED_HW_TYPE capability

[Anshuman Khandual]

On 7/24/23 19:14, James Clark wrote:
> This capability gives us the ability to open PERF_TYPE_HARDWARE and
> PERF_TYPE_HW_CACHE events on a specific PMU for free. All the
> implementation is contained in the Perf core and tool code so no change
> to the Arm PMU driver is needed.
> 
> The following basic use case now results in Perf opening the event on
> all PMUs rather than picking only one in an unpredictable way:
> 
>   $ perf stat -e cycles -- taskset --cpu-list 0,1 stress -c 2
> 
>    Performance counter stats for 'taskset --cpu-list 0,1 stress -c 2':
> 
>          963279620      armv8_cortex_a57/cycles/                (99.19%)
>          752745657      armv8_cortex_a53/cycles/                (94.80%)
> 
> Fixes: 55bcf6ef314a ("perf: Extend PERF_TYPE_HARDWARE and PERF_TYPE_HW_CACHE")
> Suggested-by: Ian Rogers <irogers@google.com>
> Acked-by: Ian Rogers <irogers@google.com>
> Signed-off-by: James Clark <james.clark@arm.com>

Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>

> ---
>  drivers/perf/arm_pmu.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/perf/arm_pmu.c b/drivers/perf/arm_pmu.c
> index f6ccb2cd4dfc..2e79201daa4a 100644
> --- a/drivers/perf/arm_pmu.c
> +++ b/drivers/perf/arm_pmu.c
> @@ -880,8 +880,13 @@ struct arm_pmu *armpmu_alloc(void)
>  		 * configuration (e.g. big.LITTLE). This is not an uncore PMU,
>  		 * and we have taken ctx sharing into account (e.g. with our
>  		 * pmu::filter callback and pmu::event_init group validation).
> +		 *
> +		 * PERF_PMU_CAP_EXTENDED_HW_TYPE is required to open
> +		 * PERF_TYPE_HARDWARE and PERF_TYPE_HW_CACHE events on a
> +		 * specific PMU.
>  		 */
> -		.capabilities	= PERF_PMU_CAP_HETEROGENEOUS_CPUS | PERF_PMU_CAP_EXTENDED_REGS,
> +		.capabilities	= PERF_PMU_CAP_HETEROGENEOUS_CPUS | PERF_PMU_CAP_EXTENDED_REGS |
> +				  PERF_PMU_CAP_EXTENDED_HW_TYPE,
>  	};
>  
>  	pmu->attr_groups[ARMPMU_ATTR_GROUP_COMMON] =

[PATCH v2 2/4] perf/x86: Remove unused PERF_PMU_CAP_HETEROGENEOUS_CPUS capability

[James Clark]

Since commit bd2756811766 ("perf: Rewrite core context handling") the
relationship between perf_event_context and PMUs has changed so that
the error scenario that PERF_PMU_CAP_HETEROGENEOUS_CPUS originally
silenced no longer exists.

Remove the capability to avoid confusion that it actually influences
any perf core behavior. This change should be a no-op.

Acked-by: Ian Rogers <irogers@google.com>
Signed-off-by: James Clark <james.clark@arm.com>
---
 arch/x86/events/core.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c
index 9d248703cbdd..2353aaf0b248 100644
--- a/arch/x86/events/core.c
+++ b/arch/x86/events/core.c
@@ -2168,7 +2168,6 @@ static int __init init_hw_perf_events(void)
 			hybrid_pmu->pmu = pmu;
 			hybrid_pmu->pmu.type = -1;
 			hybrid_pmu->pmu.attr_update = x86_pmu.attr_update;
-			hybrid_pmu->pmu.capabilities |= PERF_PMU_CAP_HETEROGENEOUS_CPUS;
 			hybrid_pmu->pmu.capabilities |= PERF_PMU_CAP_EXTENDED_HW_TYPE;
 
 			err = perf_pmu_register(&hybrid_pmu->pmu, hybrid_pmu->name,
-- 
2.34.1

[PATCH v2 3/4] arm_pmu: Remove unused PERF_PMU_CAP_HETEROGENEOUS_CPUS capability

[James Clark]

Since commit bd2756811766 ("perf: Rewrite core context handling") the
relationship between perf_event_context and PMUs has changed so that
the error scenario that PERF_PMU_CAP_HETEROGENEOUS_CPUS originally
silenced no longer exists.

Remove the capability and associated comment to avoid confusion that it
actually influences any perf core behavior. This change should be a
no-op.

Acked-by: Ian Rogers <irogers@google.com>
Signed-off-by: James Clark <james.clark@arm.com>
---
 drivers/perf/arm_pmu.c | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/drivers/perf/arm_pmu.c b/drivers/perf/arm_pmu.c
index 2e79201daa4a..d712a19e47ac 100644
--- a/drivers/perf/arm_pmu.c
+++ b/drivers/perf/arm_pmu.c
@@ -877,15 +877,12 @@ struct arm_pmu *armpmu_alloc(void)
 		.attr_groups	= pmu->attr_groups,
 		/*
 		 * This is a CPU PMU potentially in a heterogeneous
-		 * configuration (e.g. big.LITTLE). This is not an uncore PMU,
-		 * and we have taken ctx sharing into account (e.g. with our
-		 * pmu::filter callback and pmu::event_init group validation).
-		 *
+		 * configuration (e.g. big.LITTLE) so
 		 * PERF_PMU_CAP_EXTENDED_HW_TYPE is required to open
 		 * PERF_TYPE_HARDWARE and PERF_TYPE_HW_CACHE events on a
 		 * specific PMU.
 		 */
-		.capabilities	= PERF_PMU_CAP_HETEROGENEOUS_CPUS | PERF_PMU_CAP_EXTENDED_REGS |
+		.capabilities	= PERF_PMU_CAP_EXTENDED_REGS |
 				  PERF_PMU_CAP_EXTENDED_HW_TYPE,
 	};
 
-- 
2.34.1

Re: [PATCH v2 3/4] arm_pmu: Remove unused PERF_PMU_CAP_HETEROGENEOUS_CPUS capability

[Anshuman Khandual]

On 7/24/23 19:14, James Clark wrote:
> Since commit bd2756811766 ("perf: Rewrite core context handling") the
> relationship between perf_event_context and PMUs has changed so that
> the error scenario that PERF_PMU_CAP_HETEROGENEOUS_CPUS originally
> silenced no longer exists.
> 
> Remove the capability and associated comment to avoid confusion that it
> actually influences any perf core behavior. This change should be a
> no-op.
> 
> Acked-by: Ian Rogers <irogers@google.com>
> Signed-off-by: James Clark <james.clark@arm.com>

Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>

> ---
>  drivers/perf/arm_pmu.c | 7 ++-----
>  1 file changed, 2 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/perf/arm_pmu.c b/drivers/perf/arm_pmu.c
> index 2e79201daa4a..d712a19e47ac 100644
> --- a/drivers/perf/arm_pmu.c
> +++ b/drivers/perf/arm_pmu.c
> @@ -877,15 +877,12 @@ struct arm_pmu *armpmu_alloc(void)
>  		.attr_groups	= pmu->attr_groups,
>  		/*
>  		 * This is a CPU PMU potentially in a heterogeneous
> -		 * configuration (e.g. big.LITTLE). This is not an uncore PMU,
> -		 * and we have taken ctx sharing into account (e.g. with our
> -		 * pmu::filter callback and pmu::event_init group validation).
> -		 *
> +		 * configuration (e.g. big.LITTLE) so
>  		 * PERF_PMU_CAP_EXTENDED_HW_TYPE is required to open
>  		 * PERF_TYPE_HARDWARE and PERF_TYPE_HW_CACHE events on a
>  		 * specific PMU.
>  		 */
> -		.capabilities	= PERF_PMU_CAP_HETEROGENEOUS_CPUS | PERF_PMU_CAP_EXTENDED_REGS |
> +		.capabilities	= PERF_PMU_CAP_EXTENDED_REGS |
>  				  PERF_PMU_CAP_EXTENDED_HW_TYPE,
>  	};
>  

[PATCH v2 4/4] perf: Remove unused PERF_PMU_CAP_HETEROGENEOUS_CPUS capability

[James Clark]

Since commit bd2756811766 ("perf: Rewrite core context handling") the
relationship between perf_event_context and PMUs has changed so that
the error scenario that PERF_PMU_CAP_HETEROGENEOUS_CPUS originally
silenced no longer exists.

Remove the capability to avoid confusion that it actually influences
any perf core behavior and shift down the following capability bits to
fill in the unused space. This change should be a no-op.

Acked-by: Ian Rogers <irogers@google.com>
Signed-off-by: James Clark <james.clark@arm.com>
---
 include/linux/perf_event.h | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 2166a69e3bf2..c617badd1e76 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -288,10 +288,9 @@ struct perf_event_pmu_context;
 #define PERF_PMU_CAP_EXTENDED_REGS		0x0008
 #define PERF_PMU_CAP_EXCLUSIVE			0x0010
 #define PERF_PMU_CAP_ITRACE			0x0020
-#define PERF_PMU_CAP_HETEROGENEOUS_CPUS		0x0040
-#define PERF_PMU_CAP_NO_EXCLUDE			0x0080
-#define PERF_PMU_CAP_AUX_OUTPUT			0x0100
-#define PERF_PMU_CAP_EXTENDED_HW_TYPE		0x0200
+#define PERF_PMU_CAP_NO_EXCLUDE			0x0040
+#define PERF_PMU_CAP_AUX_OUTPUT			0x0080
+#define PERF_PMU_CAP_EXTENDED_HW_TYPE		0x0100
 
 struct perf_output_handle;
 
-- 
2.34.1

Re: [PATCH v2 4/4] perf: Remove unused PERF_PMU_CAP_HETEROGENEOUS_CPUS capability

[Anshuman Khandual]

On 7/24/23 19:14, James Clark wrote:
> Since commit bd2756811766 ("perf: Rewrite core context handling") the
> relationship between perf_event_context and PMUs has changed so that
> the error scenario that PERF_PMU_CAP_HETEROGENEOUS_CPUS originally
> silenced no longer exists.
> 
> Remove the capability to avoid confusion that it actually influences
> any perf core behavior and shift down the following capability bits to
> fill in the unused space. This change should be a no-op.
> 
> Acked-by: Ian Rogers <irogers@google.com>
> Signed-off-by: James Clark <james.clark@arm.com>

Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>

> ---
>  include/linux/perf_event.h | 7 +++----
>  1 file changed, 3 insertions(+), 4 deletions(-)
> 
> diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
> index 2166a69e3bf2..c617badd1e76 100644
> --- a/include/linux/perf_event.h
> +++ b/include/linux/perf_event.h
> @@ -288,10 +288,9 @@ struct perf_event_pmu_context;
>  #define PERF_PMU_CAP_EXTENDED_REGS		0x0008
>  #define PERF_PMU_CAP_EXCLUSIVE			0x0010
>  #define PERF_PMU_CAP_ITRACE			0x0020
> -#define PERF_PMU_CAP_HETEROGENEOUS_CPUS		0x0040
> -#define PERF_PMU_CAP_NO_EXCLUDE			0x0080
> -#define PERF_PMU_CAP_AUX_OUTPUT			0x0100
> -#define PERF_PMU_CAP_EXTENDED_HW_TYPE		0x0200
> +#define PERF_PMU_CAP_NO_EXCLUDE			0x0040
> +#define PERF_PMU_CAP_AUX_OUTPUT			0x0080
> +#define PERF_PMU_CAP_EXTENDED_HW_TYPE		0x0100
>  
>  struct perf_output_handle;
>  

Re: [PATCH v2 0/4] arm_pmu: Add PERF_PMU_CAP_EXTENDED_HW_TYPE capability

[Peter Zijlstra]

On Mon, Jul 24, 2023 at 02:44:55PM +0100, James Clark wrote:

> James Clark (4):
>   arm_pmu: Add PERF_PMU_CAP_EXTENDED_HW_TYPE capability
>   perf/x86: Remove unused PERF_PMU_CAP_HETEROGENEOUS_CPUS capability
>   arm_pmu: Remove unused PERF_PMU_CAP_HETEROGENEOUS_CPUS capability
>   perf: Remove unused PERF_PMU_CAP_HETEROGENEOUS_CPUS capability
> 
>  arch/x86/events/core.c     |  1 -
>  drivers/perf/arm_pmu.c     | 10 ++++++----
>  include/linux/perf_event.h |  7 +++----
>  3 files changed, 9 insertions(+), 9 deletions(-)

Thanks!

Re: [PATCH v2 0/4] arm_pmu: Add PERF_PMU_CAP_EXTENDED_HW_TYPE capability

[Mark Rutland]

On Tue, Jul 25, 2023 at 02:10:23PM +0200, Peter Zijlstra wrote:
> On Mon, Jul 24, 2023 at 02:44:55PM +0100, James Clark wrote:
> 
> > James Clark (4):
> >   arm_pmu: Add PERF_PMU_CAP_EXTENDED_HW_TYPE capability
> >   perf/x86: Remove unused PERF_PMU_CAP_HETEROGENEOUS_CPUS capability
> >   arm_pmu: Remove unused PERF_PMU_CAP_HETEROGENEOUS_CPUS capability
> >   perf: Remove unused PERF_PMU_CAP_HETEROGENEOUS_CPUS capability
> > 
> >  arch/x86/events/core.c     |  1 -
> >  drivers/perf/arm_pmu.c     | 10 ++++++----
> >  include/linux/perf_event.h |  7 +++----
> >  3 files changed, 9 insertions(+), 9 deletions(-)
> 
> Thanks!

Ah, I see that you've queued that in your perf/core branch in your queue tree.

Given that, I assume you don't need anything from me or from Will, but just in
case, for the series:

Acked-by: Mark Rutland <mark.rutland@arm.com>

Mark.