| Message ID | 20190503232407.37195-3-jeremy.linton@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | arm64: SPE ACPI enablement | expand |
On 2019/5/4 7:24, Jeremy Linton wrote: > ACPI 6.3 adds a flag to indicate that child nodes are all > identical cores. This is useful to authoritatively determine > if a set of (possibly offline) cores are identical or not. > > Since the flag doesn't give us a unique id we can generate > one and use it to create bitmaps of sibling nodes, or simply > in a loop to determine if a subset of cores are identical. > > Signed-off-by: Jeremy Linton <jeremy.linton@arm.com> > --- > drivers/acpi/pptt.c | 26 ++++++++++++++++++++++++++ > include/linux/acpi.h | 5 +++++ > 2 files changed, 31 insertions(+) > > diff --git a/drivers/acpi/pptt.c b/drivers/acpi/pptt.c > index 83a026765faa..1865515297ca 100644 > --- a/drivers/acpi/pptt.c > +++ b/drivers/acpi/pptt.c > @@ -660,3 +660,29 @@ int find_acpi_cpu_topology_package(unsigned int cpu) > return find_acpi_cpu_topology_tag(cpu, PPTT_ABORT_PACKAGE, > ACPI_PPTT_PHYSICAL_PACKAGE); > } > + > +/** > + * find_acpi_cpu_topology_hetero_id() - Get a core architecture tag > + * @cpu: Kernel logical CPU number > + * > + * Determine a unique heterogeneous tag for the given CPU. CPUs with the same > + * implementation should have matching tags. > + * > + * The returned tag can be used to group peers with identical implementation. > + * > + * The search terminates when a level is found with the identical implementation > + * flag set or we reach a root node. > + * > + * Due to limitations in the PPTT data structure, there may be rare situations > + * where two cores in a heterogeneous machine may be identical, but won't have > + * the same tag. > + * > + * Return: -ENOENT if the PPTT doesn't exist, or the CPU cannot be found. > + * Otherwise returns a value which represents a group of identical cores > + * similar to this CPU. > + */ > +int find_acpi_cpu_topology_hetero_id(unsigned int cpu) > +{ > + return find_acpi_cpu_topology_tag(cpu, PPTT_ABORT_PACKAGE, > + ACPI_PPTT_ACPI_IDENTICAL); > +} > diff --git a/include/linux/acpi.h b/include/linux/acpi.h > index d5dcebd7aad3..1444fb042898 100644 > --- a/include/linux/acpi.h > +++ b/include/linux/acpi.h > @@ -1309,6 +1309,7 @@ static inline int lpit_read_residency_count_address(u64 *address) > #ifdef CONFIG_ACPI_PPTT > int find_acpi_cpu_topology(unsigned int cpu, int level); > int find_acpi_cpu_topology_package(unsigned int cpu); > +int find_acpi_cpu_topology_hetero_id(unsigned int cpu); > int find_acpi_cpu_cache_topology(unsigned int cpu, int level); > #else > static inline int find_acpi_cpu_topology(unsigned int cpu, int level) > @@ -1319,6 +1320,10 @@ static inline int find_acpi_cpu_topology_package(unsigned int cpu) > { > return -EINVAL; > } static inline int find_acpi_cpu_topology_hetero_id(unsigned int cpu) > +static int find_acpi_cpu_topology_hetero_id(unsigned int cpu) > +{ > + return -EINVAL; > +} > static inline int find_acpi_cpu_cache_topology(unsigned int cpu, int level) > { > return -EINVAL;
Hi, On 5/5/19 2:09 AM, Kefeng Wang wrote: > > On 2019/5/4 7:24, Jeremy Linton wrote: >> ACPI 6.3 adds a flag to indicate that child nodes are all >> identical cores. This is useful to authoritatively determine >> if a set of (possibly offline) cores are identical or not. >> >> Since the flag doesn't give us a unique id we can generate >> one and use it to create bitmaps of sibling nodes, or simply >> in a loop to determine if a subset of cores are identical. >> >> Signed-off-by: Jeremy Linton <jeremy.linton@arm.com> >> --- >> drivers/acpi/pptt.c | 26 ++++++++++++++++++++++++++ >> include/linux/acpi.h | 5 +++++ >> 2 files changed, 31 insertions(+) >> >> diff --git a/drivers/acpi/pptt.c b/drivers/acpi/pptt.c >> index 83a026765faa..1865515297ca 100644 >> --- a/drivers/acpi/pptt.c >> +++ b/drivers/acpi/pptt.c >> @@ -660,3 +660,29 @@ int find_acpi_cpu_topology_package(unsigned int cpu) >> return find_acpi_cpu_topology_tag(cpu, PPTT_ABORT_PACKAGE, >> ACPI_PPTT_PHYSICAL_PACKAGE); >> } >> + >> +/** >> + * find_acpi_cpu_topology_hetero_id() - Get a core architecture tag >> + * @cpu: Kernel logical CPU number >> + * >> + * Determine a unique heterogeneous tag for the given CPU. CPUs with the same >> + * implementation should have matching tags. >> + * >> + * The returned tag can be used to group peers with identical implementation. >> + * >> + * The search terminates when a level is found with the identical implementation >> + * flag set or we reach a root node. >> + * >> + * Due to limitations in the PPTT data structure, there may be rare situations >> + * where two cores in a heterogeneous machine may be identical, but won't have >> + * the same tag. >> + * >> + * Return: -ENOENT if the PPTT doesn't exist, or the CPU cannot be found. >> + * Otherwise returns a value which represents a group of identical cores >> + * similar to this CPU. >> + */ >> +int find_acpi_cpu_topology_hetero_id(unsigned int cpu) >> +{ >> + return find_acpi_cpu_topology_tag(cpu, PPTT_ABORT_PACKAGE, >> + ACPI_PPTT_ACPI_IDENTICAL); >> +} >> diff --git a/include/linux/acpi.h b/include/linux/acpi.h >> index d5dcebd7aad3..1444fb042898 100644 >> --- a/include/linux/acpi.h >> +++ b/include/linux/acpi.h >> @@ -1309,6 +1309,7 @@ static inline int lpit_read_residency_count_address(u64 *address) >> #ifdef CONFIG_ACPI_PPTT >> int find_acpi_cpu_topology(unsigned int cpu, int level); >> int find_acpi_cpu_topology_package(unsigned int cpu); >> +int find_acpi_cpu_topology_hetero_id(unsigned int cpu); >> int find_acpi_cpu_cache_topology(unsigned int cpu, int level); >> #else >> static inline int find_acpi_cpu_topology(unsigned int cpu, int level) >> @@ -1319,6 +1320,10 @@ static inline int find_acpi_cpu_topology_package(unsigned int cpu) >> { >> return -EINVAL; >> } > static inline int find_acpi_cpu_topology_hetero_id(unsigned int cpu) Yes, good catch, I just saw that warning. >> +static int find_acpi_cpu_topology_hetero_id(unsigned int cpu) >> +{ >> + return -EINVAL; >> +} >> static inline int find_acpi_cpu_cache_topology(unsigned int cpu, int level) >> { >> return -EINVAL; >
On Fri, May 03, 2019 at 06:24:04PM -0500, Jeremy Linton wrote: > ACPI 6.3 adds a flag to indicate that child nodes are all > identical cores. This is useful to authoritatively determine > if a set of (possibly offline) cores are identical or not. > > Since the flag doesn't give us a unique id we can generate > one and use it to create bitmaps of sibling nodes, or simply > in a loop to determine if a subset of cores are identical. > If possible reorder this patch with next just to be sure. I know the user is not introduced until 4/5, but 3/5 kind of fixes the implementation. Apart from that, this looks fine to me. Reviewed-by: Sudeep Holla <sudeep.holla@arm.com> > Signed-off-by: Jeremy Linton <jeremy.linton@arm.com> > --- > drivers/acpi/pptt.c | 26 ++++++++++++++++++++++++++ > include/linux/acpi.h | 5 +++++ > 2 files changed, 31 insertions(+) > > diff --git a/drivers/acpi/pptt.c b/drivers/acpi/pptt.c > index 83a026765faa..1865515297ca 100644 > --- a/drivers/acpi/pptt.c > +++ b/drivers/acpi/pptt.c > @@ -660,3 +660,29 @@ int find_acpi_cpu_topology_package(unsigned int cpu) > return find_acpi_cpu_topology_tag(cpu, PPTT_ABORT_PACKAGE, > ACPI_PPTT_PHYSICAL_PACKAGE); > } > + > +/** > + * find_acpi_cpu_topology_hetero_id() - Get a core architecture tag > + * @cpu: Kernel logical CPU number > + * > + * Determine a unique heterogeneous tag for the given CPU. CPUs with the same > + * implementation should have matching tags. > + * > + * The returned tag can be used to group peers with identical implementation. > + * > + * The search terminates when a level is found with the identical implementation > + * flag set or we reach a root node. > + * > + * Due to limitations in the PPTT data structure, there may be rare situations > + * where two cores in a heterogeneous machine may be identical, but won't have > + * the same tag. > + * Indeed, it's unfortunate. I gave some thoughts if we can find ways to avoid this. Hope we don't have to see such weird combinations with ACPI based systems. -- Regards, Sudeep
diff --git a/drivers/acpi/pptt.c b/drivers/acpi/pptt.c index 83a026765faa..1865515297ca 100644 --- a/drivers/acpi/pptt.c +++ b/drivers/acpi/pptt.c @@ -660,3 +660,29 @@ int find_acpi_cpu_topology_package(unsigned int cpu) return find_acpi_cpu_topology_tag(cpu, PPTT_ABORT_PACKAGE, ACPI_PPTT_PHYSICAL_PACKAGE); } + +/** + * find_acpi_cpu_topology_hetero_id() - Get a core architecture tag + * @cpu: Kernel logical CPU number + * + * Determine a unique heterogeneous tag for the given CPU. CPUs with the same + * implementation should have matching tags. + * + * The returned tag can be used to group peers with identical implementation. + * + * The search terminates when a level is found with the identical implementation + * flag set or we reach a root node. + * + * Due to limitations in the PPTT data structure, there may be rare situations + * where two cores in a heterogeneous machine may be identical, but won't have + * the same tag. + * + * Return: -ENOENT if the PPTT doesn't exist, or the CPU cannot be found. + * Otherwise returns a value which represents a group of identical cores + * similar to this CPU. + */ +int find_acpi_cpu_topology_hetero_id(unsigned int cpu) +{ + return find_acpi_cpu_topology_tag(cpu, PPTT_ABORT_PACKAGE, + ACPI_PPTT_ACPI_IDENTICAL); +} diff --git a/include/linux/acpi.h b/include/linux/acpi.h index d5dcebd7aad3..1444fb042898 100644 --- a/include/linux/acpi.h +++ b/include/linux/acpi.h @@ -1309,6 +1309,7 @@ static inline int lpit_read_residency_count_address(u64 *address) #ifdef CONFIG_ACPI_PPTT int find_acpi_cpu_topology(unsigned int cpu, int level); int find_acpi_cpu_topology_package(unsigned int cpu); +int find_acpi_cpu_topology_hetero_id(unsigned int cpu); int find_acpi_cpu_cache_topology(unsigned int cpu, int level); #else static inline int find_acpi_cpu_topology(unsigned int cpu, int level) @@ -1319,6 +1320,10 @@ static inline int find_acpi_cpu_topology_package(unsigned int cpu) { return -EINVAL; } +static int find_acpi_cpu_topology_hetero_id(unsigned int cpu) +{ + return -EINVAL; +} static inline int find_acpi_cpu_cache_topology(unsigned int cpu, int level) { return -EINVAL;
ACPI 6.3 adds a flag to indicate that child nodes are all identical cores. This is useful to authoritatively determine if a set of (possibly offline) cores are identical or not. Since the flag doesn't give us a unique id we can generate one and use it to create bitmaps of sibling nodes, or simply in a loop to determine if a subset of cores are identical. Signed-off-by: Jeremy Linton <jeremy.linton@arm.com> --- drivers/acpi/pptt.c | 26 ++++++++++++++++++++++++++ include/linux/acpi.h | 5 +++++ 2 files changed, 31 insertions(+)