Re: [PATCH V8 08/10] powerpc, perf: Change POWER8 PMU configuration to work with SW filters
On 06/10/2015 11:19 AM, Daniel Axtens wrote:
On Mon, 2015-06-08 at 17:08 +0530, Anshuman Khandual wrote:
The kernel now supports SW based branch filters for book3s systems with
some specific requirements while dealing with HW supported branch filters
in order to achieve overall OR semantics prevailing in perf branch stack
sampling framework. This patch adapts the BHRB branch filter configuration
to meet those protocols. POWER8 PMU can only handle one HW based branch
filter request at any point of time. For all other combinations PMU will
pass it on to the SW.
Signed-off-by: Anshuman Khandual khand...@linux.vnet.ibm.com
---
arch/powerpc/perf/power8-pmu.c | 51
--
1 file changed, 44 insertions(+), 7 deletions(-)
diff --git a/arch/powerpc/perf/power8-pmu.c
b/arch/powerpc/perf/power8-pmu.c
index 5e17cb5..8fccf6c 100644
--- a/arch/powerpc/perf/power8-pmu.c
+++ b/arch/powerpc/perf/power8-pmu.c
@@ -656,6 +656,16 @@ static int power8_generic_events[] = {
This is, I think, the third time you've modified this function in this
patch series. I appreciate the fact that you're trying to keep logical
changes separate, but it seems to me like this change might be able to
be combined with patch 4, and given a single commit message that clearly
explains the complete scope of the changes.
Here I have to disagree with you. The changes in this patch like PMU
should not handle multiple filter requests as it does not support the
OR semantic required in the protocol, the fact that we need to pass
on the entire branch filtering responsibility to the SW comes into
picture after we have enabled the SW branch filtering support in the
previous patch. So these changes have to follow that up logically and
sequentially in that order.
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Re: [PATCH V8 08/10] powerpc, perf: Change POWER8 PMU configuration to work with SW filters
On Wed, 2015-06-10 at 17:40 +0530, Anshuman Khandual wrote:
On 06/10/2015 11:19 AM, Daniel Axtens wrote:
On Mon, 2015-06-08 at 17:08 +0530, Anshuman Khandual wrote:
The kernel now supports SW based branch filters for book3s systems with
some specific requirements while dealing with HW supported branch filters
in order to achieve overall OR semantics prevailing in perf branch stack
sampling framework. This patch adapts the BHRB branch filter
configuration
to meet those protocols. POWER8 PMU can only handle one HW based branch
filter request at any point of time. For all other combinations PMU will
pass it on to the SW.
Signed-off-by: Anshuman Khandual khand...@linux.vnet.ibm.com
---
arch/powerpc/perf/power8-pmu.c | 51
--
1 file changed, 44 insertions(+), 7 deletions(-)
diff --git a/arch/powerpc/perf/power8-pmu.c
b/arch/powerpc/perf/power8-pmu.c
index 5e17cb5..8fccf6c 100644
--- a/arch/powerpc/perf/power8-pmu.c
+++ b/arch/powerpc/perf/power8-pmu.c
@@ -656,6 +656,16 @@ static int power8_generic_events[] = {
This is, I think, the third time you've modified this function in this
patch series. I appreciate the fact that you're trying to keep logical
changes separate, but it seems to me like this change might be able to
be combined with patch 4, and given a single commit message that clearly
explains the complete scope of the changes.
Here I have to disagree with you. The changes in this patch like PMU
should not handle multiple filter requests as it does not support the
OR semantic required in the protocol, the fact that we need to pass
on the entire branch filtering responsibility to the SW comes into
picture after we have enabled the SW branch filtering support in the
previous patch. So these changes have to follow that up logically and
sequentially in that order.
OK. I don't think I understand the patch set quite well enough to follow
your logic, but when you send out the next version I'll try to take a
closer look at how the series fits together as a whole.
--
Regards,
Daniel
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Re: [PATCH V8 08/10] powerpc, perf: Change POWER8 PMU configuration to work with SW filters
On Mon, 2015-06-08 at 17:08 +0530, Anshuman Khandual wrote:
The kernel now supports SW based branch filters for book3s systems with
some specific requirements while dealing with HW supported branch filters
in order to achieve overall OR semantics prevailing in perf branch stack
sampling framework. This patch adapts the BHRB branch filter configuration
to meet those protocols. POWER8 PMU can only handle one HW based branch
filter request at any point of time. For all other combinations PMU will
pass it on to the SW.
Signed-off-by: Anshuman Khandual khand...@linux.vnet.ibm.com
---
arch/powerpc/perf/power8-pmu.c | 51
--
1 file changed, 44 insertions(+), 7 deletions(-)
diff --git a/arch/powerpc/perf/power8-pmu.c b/arch/powerpc/perf/power8-pmu.c
index 5e17cb5..8fccf6c 100644
--- a/arch/powerpc/perf/power8-pmu.c
+++ b/arch/powerpc/perf/power8-pmu.c
@@ -656,6 +656,16 @@ static int power8_generic_events[] = {
This is, I think, the third time you've modified this function in this
patch series. I appreciate the fact that you're trying to keep logical
changes separate, but it seems to me like this change might be able to
be combined with patch 4, and given a single commit message that clearly
explains the complete scope of the changes.
static u64 power8_bhrb_filter_map(u64 branch_sample_type, u64 *bhrb_filter)
{
+ u64 x, pmu_bhrb_filter;
+
+ pmu_bhrb_filter = 0;
+ *bhrb_filter = 0;
+
+ if (branch_sample_type PERF_SAMPLE_BRANCH_ANY) {
+ *bhrb_filter = PERF_SAMPLE_BRANCH_ANY;
+ return pmu_bhrb_filter;
+ }
+
/* BHRB and regular PMU events share the same privilege state
* filter configuration. BHRB is always recorded along with a
* regular PMU event. As the privilege state filter is handled
@@ -666,15 +676,42 @@ static u64 power8_bhrb_filter_map(u64
branch_sample_type, u64 *bhrb_filter)
/* Ignore user, kernel, hv bits */
branch_sample_type = ~PERF_SAMPLE_BRANCH_PLM_ALL;
- /* No branch filter requested */
- if (branch_sample_type == PERF_SAMPLE_BRANCH_ANY)
- return 0;
+ /*
+ * POWER8 does not support ORing of PMU HW branch filters. Hence
+ * if multiple branch filters are requested which may include filters
+ * supported in PMU, still go ahead and clear the PMU based HW branch
+ * filter component as in this case all the filters will be processed
+ * in SW.
+ */
- if (branch_sample_type == PERF_SAMPLE_BRANCH_ANY_CALL)
- return POWER8_MMCRA_IFM1;
+ for_each_branch_sample_type(x) {
+ /* Ignore privilege branch filters */
+ if ((x == PERF_SAMPLE_BRANCH_USER)
+ || (x == PERF_SAMPLE_BRANCH_KERNEL)
+ || (x == PERF_SAMPLE_BRANCH_HV))
+ continue;
+
+ if (!(branch_sample_type x))
+ continue;
+
+ /* Supported individual PMU branch filters */
+ if (branch_sample_type PERF_SAMPLE_BRANCH_ANY_CALL) {
+ branch_sample_type = ~PERF_SAMPLE_BRANCH_ANY_CALL;
+ if (branch_sample_type) {
+ /* Multiple filters will be processed in SW */
+ pmu_bhrb_filter = 0;
+ *bhrb_filter = 0;
+ return pmu_bhrb_filter;
+ } else {
+ /* Individual filter will be processed in HW */
+ pmu_bhrb_filter |= POWER8_MMCRA_IFM1;
+ *bhrb_filter|= PERF_SAMPLE_BRANCH_ANY_CALL;
+ return pmu_bhrb_filter;
+ }
+ }
+ }
- /* Every thing else is unsupported */
- return -1;
+ return pmu_bhrb_filter;
}
Regards,
Daniel
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[PATCH V8 08/10] powerpc, perf: Change POWER8 PMU configuration to work with SW filters
The kernel now supports SW based branch filters for book3s systems with
some specific requirements while dealing with HW supported branch filters
in order to achieve overall OR semantics prevailing in perf branch stack
sampling framework. This patch adapts the BHRB branch filter configuration
to meet those protocols. POWER8 PMU can only handle one HW based branch
filter request at any point of time. For all other combinations PMU will
pass it on to the SW.
Signed-off-by: Anshuman Khandual khand...@linux.vnet.ibm.com
---
arch/powerpc/perf/power8-pmu.c | 51 --
1 file changed, 44 insertions(+), 7 deletions(-)
diff --git a/arch/powerpc/perf/power8-pmu.c b/arch/powerpc/perf/power8-pmu.c
index 5e17cb5..8fccf6c 100644
--- a/arch/powerpc/perf/power8-pmu.c
+++ b/arch/powerpc/perf/power8-pmu.c
@@ -656,6 +656,16 @@ static int power8_generic_events[] = {
static u64 power8_bhrb_filter_map(u64 branch_sample_type, u64 *bhrb_filter)
{
+ u64 x, pmu_bhrb_filter;
+
+ pmu_bhrb_filter = 0;
+ *bhrb_filter = 0;
+
+ if (branch_sample_type PERF_SAMPLE_BRANCH_ANY) {
+ *bhrb_filter = PERF_SAMPLE_BRANCH_ANY;
+ return pmu_bhrb_filter;
+ }
+
/* BHRB and regular PMU events share the same privilege state
* filter configuration. BHRB is always recorded along with a
* regular PMU event. As the privilege state filter is handled
@@ -666,15 +676,42 @@ static u64 power8_bhrb_filter_map(u64 branch_sample_type,
u64 *bhrb_filter)
/* Ignore user, kernel, hv bits */
branch_sample_type = ~PERF_SAMPLE_BRANCH_PLM_ALL;
- /* No branch filter requested */
- if (branch_sample_type == PERF_SAMPLE_BRANCH_ANY)
- return 0;
+ /*
+* POWER8 does not support ORing of PMU HW branch filters. Hence
+* if multiple branch filters are requested which may include filters
+* supported in PMU, still go ahead and clear the PMU based HW branch
+* filter component as in this case all the filters will be processed
+* in SW.
+*/
- if (branch_sample_type == PERF_SAMPLE_BRANCH_ANY_CALL)
- return POWER8_MMCRA_IFM1;
+ for_each_branch_sample_type(x) {
+ /* Ignore privilege branch filters */
+ if ((x == PERF_SAMPLE_BRANCH_USER)
+ || (x == PERF_SAMPLE_BRANCH_KERNEL)
+ || (x == PERF_SAMPLE_BRANCH_HV))
+ continue;
+
+ if (!(branch_sample_type x))
+ continue;
+
+ /* Supported individual PMU branch filters */
+ if (branch_sample_type PERF_SAMPLE_BRANCH_ANY_CALL) {
+ branch_sample_type = ~PERF_SAMPLE_BRANCH_ANY_CALL;
+ if (branch_sample_type) {
+ /* Multiple filters will be processed in SW */
+ pmu_bhrb_filter = 0;
+ *bhrb_filter = 0;
+ return pmu_bhrb_filter;
+ } else {
+ /* Individual filter will be processed in HW */
+ pmu_bhrb_filter |= POWER8_MMCRA_IFM1;
+ *bhrb_filter|= PERF_SAMPLE_BRANCH_ANY_CALL;
+ return pmu_bhrb_filter;
+ }
+ }
+ }
- /* Every thing else is unsupported */
- return -1;
+ return pmu_bhrb_filter;
}
static void power8_config_bhrb(u64 pmu_bhrb_filter)
--
2.1.0
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