It is possible to optimize metrics when all SMT threads (CPUs) on a
core are measuring events in system wide mode. For example, TMA
metrics defines CORE_CLKS for Sandybrdige as:
if SMT is disabled:
CPU_CLK_UNHALTED.THREAD
if SMT is enabled and recording on all SMT threads:
CPU_CLK_UNHALTED.THREAD_ANY / 2
if SMT is enabled and not recording on all SMT threads:
(CPU_CLK_UNHALTED.THREAD/2)*
(1+CPU_CLK_UNHALTED.ONE_THREAD_ACTIVE/CPU_CLK_UNHALTED.REF_XCLK )
That is two more events are necessary when not gathering counts on all
SMT threads. To distinguish all SMT threads on a core vs system wide
(all CPUs) call the new property core wide. Add a core wide test that
determines the property from user requested CPUs, the topology and
system wide. System wide is required as other processes running on a
SMT thread will change the counts.
Signed-off-by: Ian Rogers <irogers@google.com>
---
tools/perf/util/cputopo.c | 46 +++++++++++++++++++++++++++++++++++++++
tools/perf/util/cputopo.h | 3 +++
tools/perf/util/smt.c | 14 ++++++++++++
tools/perf/util/smt.h | 7 ++++++
4 files changed, 70 insertions(+)
diff --git a/tools/perf/util/cputopo.c b/tools/perf/util/cputopo.c
index 511002e52714..1a3ff6449158 100644
--- a/tools/perf/util/cputopo.c
+++ b/tools/perf/util/cputopo.c
@@ -172,6 +172,52 @@ bool cpu_topology__smt_on(const struct cpu_topology *topology)
return false;
}
+bool cpu_topology__core_wide(const struct cpu_topology *topology,
+ const char *user_requested_cpu_list)
+{
+ struct perf_cpu_map *user_requested_cpus;
+
+ /*
+ * If user_requested_cpu_list is empty then all CPUs are recorded and so
+ * core_wide is true.
+ */
+ if (!user_requested_cpu_list)
+ return true;
+
+ user_requested_cpus = perf_cpu_map__new(user_requested_cpu_list);
+ /* Check that every user requested CPU is the complete set of SMT threads on a core. */
+ for (u32 i = 0; i < topology->core_cpus_lists; i++) {
+ const char *core_cpu_list = topology->core_cpus_list[i];
+ struct perf_cpu_map *core_cpus = perf_cpu_map__new(core_cpu_list);
+ struct perf_cpu cpu;
+ int idx;
+ bool has_first, first = true;
+
+ perf_cpu_map__for_each_cpu(cpu, idx, core_cpus) {
+ if (first) {
+ has_first = perf_cpu_map__has(user_requested_cpus, cpu);
+ first = false;
+ } else {
+ /*
+ * If the first core CPU is user requested then
+ * all subsequent CPUs in the core must be user
+ * requested too. If the first CPU isn't user
+ * requested then none of the others must be
+ * too.
+ */
+ if (perf_cpu_map__has(user_requested_cpus, cpu) != has_first) {
+ perf_cpu_map__put(core_cpus);
+ perf_cpu_map__put(user_requested_cpus);
+ return false;
+ }
+ }
+ }
+ perf_cpu_map__put(core_cpus);
+ }
+ perf_cpu_map__put(user_requested_cpus);
+ return true;
+}
+
static bool has_die_topology(void)
{
char filename[MAXPATHLEN];
diff --git a/tools/perf/util/cputopo.h b/tools/perf/util/cputopo.h
index 469db775a13c..969e5920a00e 100644
--- a/tools/perf/util/cputopo.h
+++ b/tools/perf/util/cputopo.h
@@ -60,6 +60,9 @@ struct cpu_topology *cpu_topology__new(void);
void cpu_topology__delete(struct cpu_topology *tp);
/* Determine from the core list whether SMT was enabled. */
bool cpu_topology__smt_on(const struct cpu_topology *topology);
+/* Are the sets of SMT siblings all enabled or all disabled in user_requested_cpus. */
+bool cpu_topology__core_wide(const struct cpu_topology *topology,
+ const char *user_requested_cpu_list);
struct numa_topology *numa_topology__new(void);
void numa_topology__delete(struct numa_topology *tp);
diff --git a/tools/perf/util/smt.c b/tools/perf/util/smt.c
index ce90c4ee4138..994e9e418227 100644
--- a/tools/perf/util/smt.c
+++ b/tools/perf/util/smt.c
@@ -21,3 +21,17 @@ bool smt_on(const struct cpu_topology *topology)
cached = true;
return cached_result;
}
+
+bool core_wide(bool system_wide, const char *user_requested_cpu_list,
+ const struct cpu_topology *topology)
+{
+ /* If not everything running on a core is being recorded then we can't use core_wide. */
+ if (!system_wide)
+ return false;
+
+ /* Cheap case that SMT is disabled and therefore we're inherently core_wide. */
+ if (!smt_on(topology))
+ return true;
+
+ return cpu_topology__core_wide(topology, user_requested_cpu_list);
+}
diff --git a/tools/perf/util/smt.h b/tools/perf/util/smt.h
index e26999c6b8d4..ae9095f2c38c 100644
--- a/tools/perf/util/smt.h
+++ b/tools/perf/util/smt.h
@@ -7,4 +7,11 @@ struct cpu_topology;
/* Returns true if SMT (aka hyperthreading) is enabled. */
bool smt_on(const struct cpu_topology *topology);
+/*
+ * Returns true when system wide and all SMT threads for a core are in the
+ * user_requested_cpus map.
+ */
+bool core_wide(bool system_wide, const char *user_requested_cpu_list,
+ const struct cpu_topology *topology);
+
#endif /* __SMT_H */
--
2.37.2.672.g94769d06f0-googEm Tue, Aug 30, 2022 at 09:48:43AM -0700, Ian Rogers escreveu:
> It is possible to optimize metrics when all SMT threads (CPUs) on a
> core are measuring events in system wide mode. For example, TMA
> metrics defines CORE_CLKS for Sandybrdige as:
>
> if SMT is disabled:
> CPU_CLK_UNHALTED.THREAD
> if SMT is enabled and recording on all SMT threads:
> CPU_CLK_UNHALTED.THREAD_ANY / 2
> if SMT is enabled and not recording on all SMT threads:
> (CPU_CLK_UNHALTED.THREAD/2)*
> (1+CPU_CLK_UNHALTED.ONE_THREAD_ACTIVE/CPU_CLK_UNHALTED.REF_XCLK )
>
> That is two more events are necessary when not gathering counts on all
> SMT threads. To distinguish all SMT threads on a core vs system wide
> (all CPUs) call the new property core wide. Add a core wide test that
> determines the property from user requested CPUs, the topology and
> system wide. System wide is required as other processes running on a
> SMT thread will change the counts.
>
> Signed-off-by: Ian Rogers <irogers@google.com>
> ---
> tools/perf/util/cputopo.c | 46 +++++++++++++++++++++++++++++++++++++++
> tools/perf/util/cputopo.h | 3 +++
> tools/perf/util/smt.c | 14 ++++++++++++
> tools/perf/util/smt.h | 7 ++++++
> 4 files changed, 70 insertions(+)
>
> diff --git a/tools/perf/util/cputopo.c b/tools/perf/util/cputopo.c
> index 511002e52714..1a3ff6449158 100644
> --- a/tools/perf/util/cputopo.c
> +++ b/tools/perf/util/cputopo.c
> @@ -172,6 +172,52 @@ bool cpu_topology__smt_on(const struct cpu_topology *topology)
> return false;
> }
>
> +bool cpu_topology__core_wide(const struct cpu_topology *topology,
> + const char *user_requested_cpu_list)
> +{
> + struct perf_cpu_map *user_requested_cpus;
> +
> + /*
> + * If user_requested_cpu_list is empty then all CPUs are recorded and so
> + * core_wide is true.
> + */
> + if (!user_requested_cpu_list)
> + return true;
> +
> + user_requested_cpus = perf_cpu_map__new(user_requested_cpu_list);
Don't we need a NULL test here?
> + /* Check that every user requested CPU is the complete set of SMT threads on a core. */
> + for (u32 i = 0; i < topology->core_cpus_lists; i++) {
> + const char *core_cpu_list = topology->core_cpus_list[i];
> + struct perf_cpu_map *core_cpus = perf_cpu_map__new(core_cpu_list);
Here too, no?
> + struct perf_cpu cpu;
> + int idx;
> + bool has_first, first = true;
> +
> + perf_cpu_map__for_each_cpu(cpu, idx, core_cpus) {
> + if (first) {
> + has_first = perf_cpu_map__has(user_requested_cpus, cpu);
> + first = false;
> + } else {
> + /*
> + * If the first core CPU is user requested then
> + * all subsequent CPUs in the core must be user
> + * requested too. If the first CPU isn't user
> + * requested then none of the others must be
> + * too.
> + */
> + if (perf_cpu_map__has(user_requested_cpus, cpu) != has_first) {
> + perf_cpu_map__put(core_cpus);
> + perf_cpu_map__put(user_requested_cpus);
> + return false;
> + }
> + }
> + }
> + perf_cpu_map__put(core_cpus);
> + }
> + perf_cpu_map__put(user_requested_cpus);
> + return true;
> +}
> +
> static bool has_die_topology(void)
> {
> char filename[MAXPATHLEN];
> diff --git a/tools/perf/util/cputopo.h b/tools/perf/util/cputopo.h
> index 469db775a13c..969e5920a00e 100644
> --- a/tools/perf/util/cputopo.h
> +++ b/tools/perf/util/cputopo.h
> @@ -60,6 +60,9 @@ struct cpu_topology *cpu_topology__new(void);
> void cpu_topology__delete(struct cpu_topology *tp);
> /* Determine from the core list whether SMT was enabled. */
> bool cpu_topology__smt_on(const struct cpu_topology *topology);
> +/* Are the sets of SMT siblings all enabled or all disabled in user_requested_cpus. */
> +bool cpu_topology__core_wide(const struct cpu_topology *topology,
> + const char *user_requested_cpu_list);
>
> struct numa_topology *numa_topology__new(void);
> void numa_topology__delete(struct numa_topology *tp);
> diff --git a/tools/perf/util/smt.c b/tools/perf/util/smt.c
> index ce90c4ee4138..994e9e418227 100644
> --- a/tools/perf/util/smt.c
> +++ b/tools/perf/util/smt.c
> @@ -21,3 +21,17 @@ bool smt_on(const struct cpu_topology *topology)
> cached = true;
> return cached_result;
> }
> +
> +bool core_wide(bool system_wide, const char *user_requested_cpu_list,
> + const struct cpu_topology *topology)
> +{
> + /* If not everything running on a core is being recorded then we can't use core_wide. */
> + if (!system_wide)
> + return false;
> +
> + /* Cheap case that SMT is disabled and therefore we're inherently core_wide. */
> + if (!smt_on(topology))
> + return true;
> +
> + return cpu_topology__core_wide(topology, user_requested_cpu_list);
> +}
> diff --git a/tools/perf/util/smt.h b/tools/perf/util/smt.h
> index e26999c6b8d4..ae9095f2c38c 100644
> --- a/tools/perf/util/smt.h
> +++ b/tools/perf/util/smt.h
> @@ -7,4 +7,11 @@ struct cpu_topology;
> /* Returns true if SMT (aka hyperthreading) is enabled. */
> bool smt_on(const struct cpu_topology *topology);
>
> +/*
> + * Returns true when system wide and all SMT threads for a core are in the
> + * user_requested_cpus map.
> + */
> +bool core_wide(bool system_wide, const char *user_requested_cpu_list,
> + const struct cpu_topology *topology);
> +
> #endif /* __SMT_H */
> --
> 2.37.2.672.g94769d06f0-goog
--
- Arnaldo
On Wed, Aug 31, 2022 at 7:40 AM Arnaldo Carvalho de Melo
<acme@kernel.org> wrote:
>
> Em Tue, Aug 30, 2022 at 09:48:43AM -0700, Ian Rogers escreveu:
> > It is possible to optimize metrics when all SMT threads (CPUs) on a
> > core are measuring events in system wide mode. For example, TMA
> > metrics defines CORE_CLKS for Sandybrdige as:
> >
> > if SMT is disabled:
> > CPU_CLK_UNHALTED.THREAD
> > if SMT is enabled and recording on all SMT threads:
> > CPU_CLK_UNHALTED.THREAD_ANY / 2
> > if SMT is enabled and not recording on all SMT threads:
> > (CPU_CLK_UNHALTED.THREAD/2)*
> > (1+CPU_CLK_UNHALTED.ONE_THREAD_ACTIVE/CPU_CLK_UNHALTED.REF_XCLK )
> >
> > That is two more events are necessary when not gathering counts on all
> > SMT threads. To distinguish all SMT threads on a core vs system wide
> > (all CPUs) call the new property core wide. Add a core wide test that
> > determines the property from user requested CPUs, the topology and
> > system wide. System wide is required as other processes running on a
> > SMT thread will change the counts.
> >
> > Signed-off-by: Ian Rogers <irogers@google.com>
> > ---
> > tools/perf/util/cputopo.c | 46 +++++++++++++++++++++++++++++++++++++++
> > tools/perf/util/cputopo.h | 3 +++
> > tools/perf/util/smt.c | 14 ++++++++++++
> > tools/perf/util/smt.h | 7 ++++++
> > 4 files changed, 70 insertions(+)
> >
> > diff --git a/tools/perf/util/cputopo.c b/tools/perf/util/cputopo.c
> > index 511002e52714..1a3ff6449158 100644
> > --- a/tools/perf/util/cputopo.c
> > +++ b/tools/perf/util/cputopo.c
> > @@ -172,6 +172,52 @@ bool cpu_topology__smt_on(const struct cpu_topology *topology)
> > return false;
> > }
> >
> > +bool cpu_topology__core_wide(const struct cpu_topology *topology,
> > + const char *user_requested_cpu_list)
> > +{
> > + struct perf_cpu_map *user_requested_cpus;
> > +
> > + /*
> > + * If user_requested_cpu_list is empty then all CPUs are recorded and so
> > + * core_wide is true.
> > + */
> > + if (!user_requested_cpu_list)
> > + return true;
> > +
> > + user_requested_cpus = perf_cpu_map__new(user_requested_cpu_list);
>
> Don't we need a NULL test here?
No, NULL is a valid perf_cpu_map, one with no values in it. For
example, see here:
https://git.kernel.org/pub/scm/linux/kernel/git/acme/linux.git/tree/tools/lib/perf/cpumap.c?h=perf/core#n266
So there's no way to tell an error (ENOMEM) from an empty map. My
suggestion is a rewrite of perf_cpu_map, I'd like to do this in a new
"libperf2" which has a more permissive than GPL license like libbpf.
That is out-of-scope here.
Thanks,
Ian
> > + /* Check that every user requested CPU is the complete set of SMT threads on a core. */
> > + for (u32 i = 0; i < topology->core_cpus_lists; i++) {
> > + const char *core_cpu_list = topology->core_cpus_list[i];
> > + struct perf_cpu_map *core_cpus = perf_cpu_map__new(core_cpu_list);
>
> Here too, no?
>
> > + struct perf_cpu cpu;
> > + int idx;
> > + bool has_first, first = true;
> > +
> > + perf_cpu_map__for_each_cpu(cpu, idx, core_cpus) {
> > + if (first) {
> > + has_first = perf_cpu_map__has(user_requested_cpus, cpu);
> > + first = false;
> > + } else {
> > + /*
> > + * If the first core CPU is user requested then
> > + * all subsequent CPUs in the core must be user
> > + * requested too. If the first CPU isn't user
> > + * requested then none of the others must be
> > + * too.
> > + */
> > + if (perf_cpu_map__has(user_requested_cpus, cpu) != has_first) {
> > + perf_cpu_map__put(core_cpus);
> > + perf_cpu_map__put(user_requested_cpus);
> > + return false;
> > + }
> > + }
> > + }
> > + perf_cpu_map__put(core_cpus);
> > + }
> > + perf_cpu_map__put(user_requested_cpus);
> > + return true;
> > +}
> > +
> > static bool has_die_topology(void)
> > {
> > char filename[MAXPATHLEN];
> > diff --git a/tools/perf/util/cputopo.h b/tools/perf/util/cputopo.h
> > index 469db775a13c..969e5920a00e 100644
> > --- a/tools/perf/util/cputopo.h
> > +++ b/tools/perf/util/cputopo.h
> > @@ -60,6 +60,9 @@ struct cpu_topology *cpu_topology__new(void);
> > void cpu_topology__delete(struct cpu_topology *tp);
> > /* Determine from the core list whether SMT was enabled. */
> > bool cpu_topology__smt_on(const struct cpu_topology *topology);
> > +/* Are the sets of SMT siblings all enabled or all disabled in user_requested_cpus. */
> > +bool cpu_topology__core_wide(const struct cpu_topology *topology,
> > + const char *user_requested_cpu_list);
> >
> > struct numa_topology *numa_topology__new(void);
> > void numa_topology__delete(struct numa_topology *tp);
> > diff --git a/tools/perf/util/smt.c b/tools/perf/util/smt.c
> > index ce90c4ee4138..994e9e418227 100644
> > --- a/tools/perf/util/smt.c
> > +++ b/tools/perf/util/smt.c
> > @@ -21,3 +21,17 @@ bool smt_on(const struct cpu_topology *topology)
> > cached = true;
> > return cached_result;
> > }
> > +
> > +bool core_wide(bool system_wide, const char *user_requested_cpu_list,
> > + const struct cpu_topology *topology)
> > +{
> > + /* If not everything running on a core is being recorded then we can't use core_wide. */
> > + if (!system_wide)
> > + return false;
> > +
> > + /* Cheap case that SMT is disabled and therefore we're inherently core_wide. */
> > + if (!smt_on(topology))
> > + return true;
> > +
> > + return cpu_topology__core_wide(topology, user_requested_cpu_list);
> > +}
> > diff --git a/tools/perf/util/smt.h b/tools/perf/util/smt.h
> > index e26999c6b8d4..ae9095f2c38c 100644
> > --- a/tools/perf/util/smt.h
> > +++ b/tools/perf/util/smt.h
> > @@ -7,4 +7,11 @@ struct cpu_topology;
> > /* Returns true if SMT (aka hyperthreading) is enabled. */
> > bool smt_on(const struct cpu_topology *topology);
> >
> > +/*
> > + * Returns true when system wide and all SMT threads for a core are in the
> > + * user_requested_cpus map.
> > + */
> > +bool core_wide(bool system_wide, const char *user_requested_cpu_list,
> > + const struct cpu_topology *topology);
> > +
> > #endif /* __SMT_H */
> > --
> > 2.37.2.672.g94769d06f0-goog
>
> --
>
> - Arnaldo
Em Wed, Aug 31, 2022 at 08:58:49AM -0700, Ian Rogers escreveu:
> On Wed, Aug 31, 2022 at 7:40 AM Arnaldo Carvalho de Melo
> <acme@kernel.org> wrote:
> >
> > Em Tue, Aug 30, 2022 at 09:48:43AM -0700, Ian Rogers escreveu:
> > > It is possible to optimize metrics when all SMT threads (CPUs) on a
> > > core are measuring events in system wide mode. For example, TMA
> > > metrics defines CORE_CLKS for Sandybrdige as:
> > >
> > > if SMT is disabled:
> > > CPU_CLK_UNHALTED.THREAD
> > > if SMT is enabled and recording on all SMT threads:
> > > CPU_CLK_UNHALTED.THREAD_ANY / 2
> > > if SMT is enabled and not recording on all SMT threads:
> > > (CPU_CLK_UNHALTED.THREAD/2)*
> > > (1+CPU_CLK_UNHALTED.ONE_THREAD_ACTIVE/CPU_CLK_UNHALTED.REF_XCLK )
> > >
> > > That is two more events are necessary when not gathering counts on all
> > > SMT threads. To distinguish all SMT threads on a core vs system wide
> > > (all CPUs) call the new property core wide. Add a core wide test that
> > > determines the property from user requested CPUs, the topology and
> > > system wide. System wide is required as other processes running on a
> > > SMT thread will change the counts.
> > >
> > > Signed-off-by: Ian Rogers <irogers@google.com>
> > > ---
> > > tools/perf/util/cputopo.c | 46 +++++++++++++++++++++++++++++++++++++++
> > > tools/perf/util/cputopo.h | 3 +++
> > > tools/perf/util/smt.c | 14 ++++++++++++
> > > tools/perf/util/smt.h | 7 ++++++
> > > 4 files changed, 70 insertions(+)
> > >
> > > diff --git a/tools/perf/util/cputopo.c b/tools/perf/util/cputopo.c
> > > index 511002e52714..1a3ff6449158 100644
> > > --- a/tools/perf/util/cputopo.c
> > > +++ b/tools/perf/util/cputopo.c
> > > @@ -172,6 +172,52 @@ bool cpu_topology__smt_on(const struct cpu_topology *topology)
> > > return false;
> > > }
> > >
> > > +bool cpu_topology__core_wide(const struct cpu_topology *topology,
> > > + const char *user_requested_cpu_list)
> > > +{
> > > + struct perf_cpu_map *user_requested_cpus;
> > > +
> > > + /*
> > > + * If user_requested_cpu_list is empty then all CPUs are recorded and so
> > > + * core_wide is true.
> > > + */
> > > + if (!user_requested_cpu_list)
> > > + return true;
> > > +
> > > + user_requested_cpus = perf_cpu_map__new(user_requested_cpu_list);
> >
> > Don't we need a NULL test here?
> No, NULL is a valid perf_cpu_map, one with no values in it. For
> example, see here:
But in this specific case, if perf_cpu_map__new() returns NULL, its
because it failed to parse user_requested_cpu_list, so checking against
NULL is valid, no?
- Arnaldo
> https://git.kernel.org/pub/scm/linux/kernel/git/acme/linux.git/tree/tools/lib/perf/cpumap.c?h=perf/core#n266
> So there's no way to tell an error (ENOMEM) from an empty map. My
> suggestion is a rewrite of perf_cpu_map, I'd like to do this in a new
> "libperf2" which has a more permissive than GPL license like libbpf.
> That is out-of-scope here.
> Thanks,
> Ian
>
> > > + /* Check that every user requested CPU is the complete set of SMT threads on a core. */
> > > + for (u32 i = 0; i < topology->core_cpus_lists; i++) {
> > > + const char *core_cpu_list = topology->core_cpus_list[i];
> > > + struct perf_cpu_map *core_cpus = perf_cpu_map__new(core_cpu_list);
> >
> > Here too, no?
> >
> > > + struct perf_cpu cpu;
> > > + int idx;
> > > + bool has_first, first = true;
> > > +
> > > + perf_cpu_map__for_each_cpu(cpu, idx, core_cpus) {
> > > + if (first) {
> > > + has_first = perf_cpu_map__has(user_requested_cpus, cpu);
> > > + first = false;
> > > + } else {
> > > + /*
> > > + * If the first core CPU is user requested then
> > > + * all subsequent CPUs in the core must be user
> > > + * requested too. If the first CPU isn't user
> > > + * requested then none of the others must be
> > > + * too.
> > > + */
> > > + if (perf_cpu_map__has(user_requested_cpus, cpu) != has_first) {
> > > + perf_cpu_map__put(core_cpus);
> > > + perf_cpu_map__put(user_requested_cpus);
> > > + return false;
> > > + }
> > > + }
> > > + }
> > > + perf_cpu_map__put(core_cpus);
> > > + }
> > > + perf_cpu_map__put(user_requested_cpus);
> > > + return true;
> > > +}
> > > +
> > > static bool has_die_topology(void)
> > > {
> > > char filename[MAXPATHLEN];
> > > diff --git a/tools/perf/util/cputopo.h b/tools/perf/util/cputopo.h
> > > index 469db775a13c..969e5920a00e 100644
> > > --- a/tools/perf/util/cputopo.h
> > > +++ b/tools/perf/util/cputopo.h
> > > @@ -60,6 +60,9 @@ struct cpu_topology *cpu_topology__new(void);
> > > void cpu_topology__delete(struct cpu_topology *tp);
> > > /* Determine from the core list whether SMT was enabled. */
> > > bool cpu_topology__smt_on(const struct cpu_topology *topology);
> > > +/* Are the sets of SMT siblings all enabled or all disabled in user_requested_cpus. */
> > > +bool cpu_topology__core_wide(const struct cpu_topology *topology,
> > > + const char *user_requested_cpu_list);
> > >
> > > struct numa_topology *numa_topology__new(void);
> > > void numa_topology__delete(struct numa_topology *tp);
> > > diff --git a/tools/perf/util/smt.c b/tools/perf/util/smt.c
> > > index ce90c4ee4138..994e9e418227 100644
> > > --- a/tools/perf/util/smt.c
> > > +++ b/tools/perf/util/smt.c
> > > @@ -21,3 +21,17 @@ bool smt_on(const struct cpu_topology *topology)
> > > cached = true;
> > > return cached_result;
> > > }
> > > +
> > > +bool core_wide(bool system_wide, const char *user_requested_cpu_list,
> > > + const struct cpu_topology *topology)
> > > +{
> > > + /* If not everything running on a core is being recorded then we can't use core_wide. */
> > > + if (!system_wide)
> > > + return false;
> > > +
> > > + /* Cheap case that SMT is disabled and therefore we're inherently core_wide. */
> > > + if (!smt_on(topology))
> > > + return true;
> > > +
> > > + return cpu_topology__core_wide(topology, user_requested_cpu_list);
> > > +}
> > > diff --git a/tools/perf/util/smt.h b/tools/perf/util/smt.h
> > > index e26999c6b8d4..ae9095f2c38c 100644
> > > --- a/tools/perf/util/smt.h
> > > +++ b/tools/perf/util/smt.h
> > > @@ -7,4 +7,11 @@ struct cpu_topology;
> > > /* Returns true if SMT (aka hyperthreading) is enabled. */
> > > bool smt_on(const struct cpu_topology *topology);
> > >
> > > +/*
> > > + * Returns true when system wide and all SMT threads for a core are in the
> > > + * user_requested_cpus map.
> > > + */
> > > +bool core_wide(bool system_wide, const char *user_requested_cpu_list,
> > > + const struct cpu_topology *topology);
> > > +
> > > #endif /* __SMT_H */
> > > --
> > > 2.37.2.672.g94769d06f0-goog
> >
> > --
> >
> > - Arnaldo
--
- Arnaldo
On Wed, Aug 31, 2022 at 9:20 AM Arnaldo Carvalho de Melo
<acme@kernel.org> wrote:
>
> Em Wed, Aug 31, 2022 at 08:58:49AM -0700, Ian Rogers escreveu:
> > On Wed, Aug 31, 2022 at 7:40 AM Arnaldo Carvalho de Melo
> > <acme@kernel.org> wrote:
> > >
> > > Em Tue, Aug 30, 2022 at 09:48:43AM -0700, Ian Rogers escreveu:
> > > > It is possible to optimize metrics when all SMT threads (CPUs) on a
> > > > core are measuring events in system wide mode. For example, TMA
> > > > metrics defines CORE_CLKS for Sandybrdige as:
> > > >
> > > > if SMT is disabled:
> > > > CPU_CLK_UNHALTED.THREAD
> > > > if SMT is enabled and recording on all SMT threads:
> > > > CPU_CLK_UNHALTED.THREAD_ANY / 2
> > > > if SMT is enabled and not recording on all SMT threads:
> > > > (CPU_CLK_UNHALTED.THREAD/2)*
> > > > (1+CPU_CLK_UNHALTED.ONE_THREAD_ACTIVE/CPU_CLK_UNHALTED.REF_XCLK )
> > > >
> > > > That is two more events are necessary when not gathering counts on all
> > > > SMT threads. To distinguish all SMT threads on a core vs system wide
> > > > (all CPUs) call the new property core wide. Add a core wide test that
> > > > determines the property from user requested CPUs, the topology and
> > > > system wide. System wide is required as other processes running on a
> > > > SMT thread will change the counts.
> > > >
> > > > Signed-off-by: Ian Rogers <irogers@google.com>
> > > > ---
> > > > tools/perf/util/cputopo.c | 46 +++++++++++++++++++++++++++++++++++++++
> > > > tools/perf/util/cputopo.h | 3 +++
> > > > tools/perf/util/smt.c | 14 ++++++++++++
> > > > tools/perf/util/smt.h | 7 ++++++
> > > > 4 files changed, 70 insertions(+)
> > > >
> > > > diff --git a/tools/perf/util/cputopo.c b/tools/perf/util/cputopo.c
> > > > index 511002e52714..1a3ff6449158 100644
> > > > --- a/tools/perf/util/cputopo.c
> > > > +++ b/tools/perf/util/cputopo.c
> > > > @@ -172,6 +172,52 @@ bool cpu_topology__smt_on(const struct cpu_topology *topology)
> > > > return false;
> > > > }
> > > >
> > > > +bool cpu_topology__core_wide(const struct cpu_topology *topology,
> > > > + const char *user_requested_cpu_list)
> > > > +{
> > > > + struct perf_cpu_map *user_requested_cpus;
> > > > +
> > > > + /*
> > > > + * If user_requested_cpu_list is empty then all CPUs are recorded and so
> > > > + * core_wide is true.
> > > > + */
> > > > + if (!user_requested_cpu_list)
> > > > + return true;
> > > > +
> > > > + user_requested_cpus = perf_cpu_map__new(user_requested_cpu_list);
> > >
> > > Don't we need a NULL test here?
>
> > No, NULL is a valid perf_cpu_map, one with no values in it. For
> > example, see here:
>
> But in this specific case, if perf_cpu_map__new() returns NULL, its
> because it failed to parse user_requested_cpu_list, so checking against
> NULL is valid, no?
What about the empty string?
Thanks,
Ian
> - Arnaldo
>
> > https://git.kernel.org/pub/scm/linux/kernel/git/acme/linux.git/tree/tools/lib/perf/cpumap.c?h=perf/core#n266
> > So there's no way to tell an error (ENOMEM) from an empty map. My
> > suggestion is a rewrite of perf_cpu_map, I'd like to do this in a new
> > "libperf2" which has a more permissive than GPL license like libbpf.
> > That is out-of-scope here.
>
> > Thanks,
> > Ian
> >
> > > > + /* Check that every user requested CPU is the complete set of SMT threads on a core. */
> > > > + for (u32 i = 0; i < topology->core_cpus_lists; i++) {
> > > > + const char *core_cpu_list = topology->core_cpus_list[i];
> > > > + struct perf_cpu_map *core_cpus = perf_cpu_map__new(core_cpu_list);
> > >
> > > Here too, no?
> > >
> > > > + struct perf_cpu cpu;
> > > > + int idx;
> > > > + bool has_first, first = true;
> > > > +
> > > > + perf_cpu_map__for_each_cpu(cpu, idx, core_cpus) {
> > > > + if (first) {
> > > > + has_first = perf_cpu_map__has(user_requested_cpus, cpu);
> > > > + first = false;
> > > > + } else {
> > > > + /*
> > > > + * If the first core CPU is user requested then
> > > > + * all subsequent CPUs in the core must be user
> > > > + * requested too. If the first CPU isn't user
> > > > + * requested then none of the others must be
> > > > + * too.
> > > > + */
> > > > + if (perf_cpu_map__has(user_requested_cpus, cpu) != has_first) {
> > > > + perf_cpu_map__put(core_cpus);
> > > > + perf_cpu_map__put(user_requested_cpus);
> > > > + return false;
> > > > + }
> > > > + }
> > > > + }
> > > > + perf_cpu_map__put(core_cpus);
> > > > + }
> > > > + perf_cpu_map__put(user_requested_cpus);
> > > > + return true;
> > > > +}
> > > > +
> > > > static bool has_die_topology(void)
> > > > {
> > > > char filename[MAXPATHLEN];
> > > > diff --git a/tools/perf/util/cputopo.h b/tools/perf/util/cputopo.h
> > > > index 469db775a13c..969e5920a00e 100644
> > > > --- a/tools/perf/util/cputopo.h
> > > > +++ b/tools/perf/util/cputopo.h
> > > > @@ -60,6 +60,9 @@ struct cpu_topology *cpu_topology__new(void);
> > > > void cpu_topology__delete(struct cpu_topology *tp);
> > > > /* Determine from the core list whether SMT was enabled. */
> > > > bool cpu_topology__smt_on(const struct cpu_topology *topology);
> > > > +/* Are the sets of SMT siblings all enabled or all disabled in user_requested_cpus. */
> > > > +bool cpu_topology__core_wide(const struct cpu_topology *topology,
> > > > + const char *user_requested_cpu_list);
> > > >
> > > > struct numa_topology *numa_topology__new(void);
> > > > void numa_topology__delete(struct numa_topology *tp);
> > > > diff --git a/tools/perf/util/smt.c b/tools/perf/util/smt.c
> > > > index ce90c4ee4138..994e9e418227 100644
> > > > --- a/tools/perf/util/smt.c
> > > > +++ b/tools/perf/util/smt.c
> > > > @@ -21,3 +21,17 @@ bool smt_on(const struct cpu_topology *topology)
> > > > cached = true;
> > > > return cached_result;
> > > > }
> > > > +
> > > > +bool core_wide(bool system_wide, const char *user_requested_cpu_list,
> > > > + const struct cpu_topology *topology)
> > > > +{
> > > > + /* If not everything running on a core is being recorded then we can't use core_wide. */
> > > > + if (!system_wide)
> > > > + return false;
> > > > +
> > > > + /* Cheap case that SMT is disabled and therefore we're inherently core_wide. */
> > > > + if (!smt_on(topology))
> > > > + return true;
> > > > +
> > > > + return cpu_topology__core_wide(topology, user_requested_cpu_list);
> > > > +}
> > > > diff --git a/tools/perf/util/smt.h b/tools/perf/util/smt.h
> > > > index e26999c6b8d4..ae9095f2c38c 100644
> > > > --- a/tools/perf/util/smt.h
> > > > +++ b/tools/perf/util/smt.h
> > > > @@ -7,4 +7,11 @@ struct cpu_topology;
> > > > /* Returns true if SMT (aka hyperthreading) is enabled. */
> > > > bool smt_on(const struct cpu_topology *topology);
> > > >
> > > > +/*
> > > > + * Returns true when system wide and all SMT threads for a core are in the
> > > > + * user_requested_cpus map.
> > > > + */
> > > > +bool core_wide(bool system_wide, const char *user_requested_cpu_list,
> > > > + const struct cpu_topology *topology);
> > > > +
> > > > #endif /* __SMT_H */
> > > > --
> > > > 2.37.2.672.g94769d06f0-goog
> > >
> > > --
> > >
> > > - Arnaldo
>
> --
>
> - Arnaldo
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