| Message ID | 20171012194856.13844-7-jeremy.linton@arm.com |
|---|---|
| State | New |
| Headers | show |
| Series | [v3,1/7] ACPI/PPTT: Add Processor Properties Topology Table parsing | expand |
Hi, I missed the rest of the comment below.. On 10/19/2017 10:56 AM, Lorenzo Pieralisi wrote: > On Thu, Oct 12, 2017 at 02:48:55PM -0500, Jeremy Linton wrote: >> Propagate the topology information from the PPTT tree to the >> cpu_topology array. We can get the thread id, core_id and >> cluster_id by assuming certain levels of the PPTT tree correspond >> to those concepts. The package_id is flagged in the tree and can be >> found by passing an arbitrary large level to setup_acpi_cpu_topology() >> which terminates its search when it finds an ACPI node flagged >> as the physical package. If the tree doesn't contain enough >> levels to represent all of thread/core/cod/package then the package >> id will be used for the missing levels. >> >> Since server/ACPI machines are more likely to be multisocket and NUMA, > > I think this stuff is vague enough already so to start with I would drop > patch 4 and 5 and stop assuming what machines are more likely to ship > with ACPI than DT. > > I am just saying, for the umpteenth time, that these levels have no > architectural meaning _whatsoever_, level is a hierarchy concept > with no architectural meaning attached. > > The only consistent thing PPTT is bringing about is the hierarchy > levels/grouping (and _possibly_ - what a package boundary is), let's > stick to that for the time being. > >> this patch also modifies the default clusters=sockets behavior >> for ACPI machines to sockets=sockets. DT machines continue to >> represent sockets as clusters. For ACPI machines, this results in a >> more normalized view of the topology. Cluster level scheduler decisions >> are still being made due to the "MC" level in the scheduler which has >> knowledge of cache sharing domains. >> >> This code is loosely based on a combination of code from: >> Xiongfeng Wang <wangxiongfeng2@huawei.com> >> John Garry <john.garry@huawei.com> >> Jeffrey Hugo <jhugo@codeaurora.org> >> >> Signed-off-by: Jeremy Linton <jeremy.linton@arm.com> >> --- >> arch/arm64/kernel/topology.c | 54 +++++++++++++++++++++++++++++++++++++++++++- >> include/linux/topology.h | 1 + >> 2 files changed, 54 insertions(+), 1 deletion(-) >> >> diff --git a/arch/arm64/kernel/topology.c b/arch/arm64/kernel/topology.c >> index 9147e5b6326d..42f3e7f28b2b 100644 >> --- a/arch/arm64/kernel/topology.c >> +++ b/arch/arm64/kernel/topology.c >> @@ -11,6 +11,7 @@ >> * for more details. >> */ >> >> +#include <linux/acpi.h> >> #include <linux/arch_topology.h> >> #include <linux/cpu.h> >> #include <linux/cpumask.h> >> @@ -22,6 +23,7 @@ >> #include <linux/sched.h> >> #include <linux/sched/topology.h> >> #include <linux/slab.h> >> +#include <linux/smp.h> >> #include <linux/string.h> >> >> #include <asm/cpu.h> >> @@ -304,6 +306,54 @@ static void __init reset_cpu_topology(void) >> } >> } >> >> +#ifdef CONFIG_ACPI >> +/* >> + * Propagate the topology information of the processor_topology_node tree to the >> + * cpu_topology array. >> + */ >> +static int __init parse_acpi_topology(void) >> +{ >> + u64 is_threaded; >> + int cpu; >> + int topology_id; >> + /* set a large depth, to hit ACPI_PPTT_PHYSICAL_PACKAGE if one exists */ >> + const int max_topo = 0xFF; >> + >> + is_threaded = read_cpuid_mpidr() & MPIDR_MT_BITMASK; >> + >> + for_each_possible_cpu(cpu) { >> + topology_id = setup_acpi_cpu_topology(cpu, 0); >> + if (topology_id < 0) >> + return topology_id; >> + >> + if (is_threaded) { >> + cpu_topology[cpu].thread_id = topology_id; >> + topology_id = setup_acpi_cpu_topology(cpu, 1); > > Nit: you can move setup_acpi_cpu_topology() to include/linux/acpi.h, > provide an empty inline function for the !ACPI case and remove > this function ACPI ifdeffery. Yah sure.. > >> + cpu_topology[cpu].core_id = topology_id; >> + topology_id = setup_acpi_cpu_topology(cpu, 2); >> + cpu_topology[cpu].cluster_id = topology_id; >> + topology_id = setup_acpi_cpu_topology(cpu, max_topo); > > If you want a package id (that's just a package tag to group cores), you > should not use a large level because you know how setup_acpi_cpu_topology()works, you should add an API that allows you to retrieve the package id > (so that you can use th ACPI_PPTT_PHYSICAL_PACKAGE flag consistenly, > whatever it represents). I don't think the spec requires the use of PHYSICAL_PACKAGE... Am I misreading it? Which means we need to "pick" a node level to represent the physical package if one doesn't exist... > > Lorenzo > >> + cpu_topology[cpu].package_id = topology_id; >> + } else { >> + cpu_topology[cpu].thread_id = -1; >> + cpu_topology[cpu].core_id = topology_id; >> + topology_id = setup_acpi_cpu_topology(cpu, 1); >> + cpu_topology[cpu].cluster_id = topology_id; >> + topology_id = setup_acpi_cpu_topology(cpu, max_topo); >> + cpu_topology[cpu].package_id = topology_id; >> + } >> + } >> + return 0; >> +} >> + >> +#else >> +static int __init parse_acpi_topology(void) >> +{ >> + /*ACPI kernels should be built with PPTT support*/ >> + return -EINVAL; >> +} >> +#endif >> + >> void __init init_cpu_topology(void) >> { >> reset_cpu_topology(); >> @@ -312,6 +362,8 @@ void __init init_cpu_topology(void) >> * Discard anything that was parsed if we hit an error so we >> * don't use partial information. >> */ >> - if (of_have_populated_dt() && parse_dt_topology()) >> + if ((!acpi_disabled) && parse_acpi_topology()) >> + reset_cpu_topology(); >> + else if (of_have_populated_dt() && parse_dt_topology()) >> reset_cpu_topology(); >> } >> diff --git a/include/linux/topology.h b/include/linux/topology.h >> index 4660749a7303..cbf2fb13bf92 100644 >> --- a/include/linux/topology.h >> +++ b/include/linux/topology.h >> @@ -43,6 +43,7 @@ >> if (nr_cpus_node(node)) >> >> int arch_update_cpu_topology(void); >> +int setup_acpi_cpu_topology(unsigned int cpu, int level); >> >> /* Conform to ACPI 2.0 SLIT distance definitions */ >> #define LOCAL_DISTANCE 10 >> -- >> 2.13.5 >>
Hi, On 10/20/2017 04:14 AM, Lorenzo Pieralisi wrote: > On Thu, Oct 19, 2017 at 11:13:27AM -0500, Jeremy Linton wrote: >> On 10/19/2017 10:56 AM, Lorenzo Pieralisi wrote: >>> On Thu, Oct 12, 2017 at 02:48:55PM -0500, Jeremy Linton wrote: >>>> Propagate the topology information from the PPTT tree to the >>>> cpu_topology array. We can get the thread id, core_id and >>>> cluster_id by assuming certain levels of the PPTT tree correspond >>>> to those concepts. The package_id is flagged in the tree and can be >>>> found by passing an arbitrary large level to setup_acpi_cpu_topology() >>>> which terminates its search when it finds an ACPI node flagged >>>> as the physical package. If the tree doesn't contain enough >>>> levels to represent all of thread/core/cod/package then the package >>>> id will be used for the missing levels. >>>> >>>> Since server/ACPI machines are more likely to be multisocket and NUMA, >>> >>> I think this stuff is vague enough already so to start with I would drop >>> patch 4 and 5 and stop assuming what machines are more likely to ship >>> with ACPI than DT. >>> >>> I am just saying, for the umpteenth time, that these levels have no >>> architectural meaning _whatsoever_, level is a hierarchy concept >>> with no architectural meaning attached. >> >> ? >> >> Did anyone say anything about that? No, I think the only thing being >> guaranteed here is that the kernel's physical_id maps to an ACPI >> defined socket. Which seems to be the mindset of pretty much the >> entire !arm64 community meaning they are optimizing their software >> and the kernel with that concept in mind. >> >> Are you denying the existence of non-uniformity between threads >> running on different physical sockets? > > No, I have not explained my POV clearly, apologies. > > AFAIK, the kernel currently deals with 2 (3 - if SMT) topology layers. > > 1) thread > 2) core > 3) package > > What I wanted to say is, that, to simplify this series, you do not need > to introduce the COD topology level, since it is just another arbitrary > topology level (ie there is no way you can pinpoint which level > corresponds to COD with PPTT - or DT for the sake of this discussion) > that would not be used in the kernel (apart from big.LITTLE cpufreq > driver and PSCI checker whose usage of topology_physical_package_id() is > questionable anyway). Oh! But, i'm at a loss as to what to do with those two users if I set the node which has the physical socket flag set, as the "cluster_id" in the topology. Granted, this being ACPI I don't expect the cpufreq driver to be active (given CPPC) and the psci checker might be ignored? Even so, its a bit of a misnomer what is actually happening. Are we good with this? > > PPTT allows you to define what level corresponds to a package, use > it to initialize the package topology level (that on ARM internal > variables we call cluster) and be done with it. > > I do not think that adding another topology level improves anything as > far as ACPI topology detection is concerned, you are not able to use it > in the scheduler or from userspace to group CPUs anyway. Correct, and AFAIK after having poked a bit at the scheduler its sort of redundant as the generic cache sharing levels are more useful anyway. > > Does this answer your question ? Yes, other than what to do with the two drivers. > > Thanks, > Lorenzo >
On 20/10/17 17:14, Jeremy Linton wrote: > Hi, > > On 10/20/2017 04:14 AM, Lorenzo Pieralisi wrote: >> On Thu, Oct 19, 2017 at 11:13:27AM -0500, Jeremy Linton wrote: >>> On 10/19/2017 10:56 AM, Lorenzo Pieralisi wrote: >>>> On Thu, Oct 12, 2017 at 02:48:55PM -0500, Jeremy Linton wrote: >>>>> Propagate the topology information from the PPTT tree to the >>>>> cpu_topology array. We can get the thread id, core_id and >>>>> cluster_id by assuming certain levels of the PPTT tree correspond >>>>> to those concepts. The package_id is flagged in the tree and can be >>>>> found by passing an arbitrary large level to setup_acpi_cpu_topology() >>>>> which terminates its search when it finds an ACPI node flagged >>>>> as the physical package. If the tree doesn't contain enough >>>>> levels to represent all of thread/core/cod/package then the package >>>>> id will be used for the missing levels. >>>>> >>>>> Since server/ACPI machines are more likely to be multisocket and NUMA, >>>> >>>> I think this stuff is vague enough already so to start with I would >>>> drop >>>> patch 4 and 5 and stop assuming what machines are more likely to ship >>>> with ACPI than DT. >>>> >>>> I am just saying, for the umpteenth time, that these levels have no >>>> architectural meaning _whatsoever_, level is a hierarchy concept >>>> with no architectural meaning attached. >>> >>> ? >>> >>> Did anyone say anything about that? No, I think the only thing being >>> guaranteed here is that the kernel's physical_id maps to an ACPI >>> defined socket. Which seems to be the mindset of pretty much the >>> entire !arm64 community meaning they are optimizing their software >>> and the kernel with that concept in mind. >>> >>> Are you denying the existence of non-uniformity between threads >>> running on different physical sockets? >> >> No, I have not explained my POV clearly, apologies. >> >> AFAIK, the kernel currently deals with 2 (3 - if SMT) topology layers. >> >> 1) thread >> 2) core >> 3) package >> >> What I wanted to say is, that, to simplify this series, you do not need >> to introduce the COD topology level, since it is just another arbitrary >> topology level (ie there is no way you can pinpoint which level >> corresponds to COD with PPTT - or DT for the sake of this discussion) >> that would not be used in the kernel (apart from big.LITTLE cpufreq >> driver and PSCI checker whose usage of topology_physical_package_id() is >> questionable anyway). Just thinking out loud here. 1. psci_checker.c : it's just used to get groups of cpu's to achieve deeper idle states. It should be easy to get rid of that. 2. big.LITTLE cpufreq : 2 users, scpi I should be able to do what I did for SCMI and for spc I am thinking if we can hard code it's just used on TC2 -- Regards, Sudeep
diff --git a/arch/arm64/kernel/topology.c b/arch/arm64/kernel/topology.c index 9147e5b6326d..42f3e7f28b2b 100644 --- a/arch/arm64/kernel/topology.c +++ b/arch/arm64/kernel/topology.c @@ -11,6 +11,7 @@ * for more details. */ +#include <linux/acpi.h> #include <linux/arch_topology.h> #include <linux/cpu.h> #include <linux/cpumask.h> @@ -22,6 +23,7 @@ #include <linux/sched.h> #include <linux/sched/topology.h> #include <linux/slab.h> +#include <linux/smp.h> #include <linux/string.h> #include <asm/cpu.h> @@ -304,6 +306,54 @@ static void __init reset_cpu_topology(void) } } +#ifdef CONFIG_ACPI +/* + * Propagate the topology information of the processor_topology_node tree to the + * cpu_topology array. + */ +static int __init parse_acpi_topology(void) +{ + u64 is_threaded; + int cpu; + int topology_id; + /* set a large depth, to hit ACPI_PPTT_PHYSICAL_PACKAGE if one exists */ + const int max_topo = 0xFF; + + is_threaded = read_cpuid_mpidr() & MPIDR_MT_BITMASK; + + for_each_possible_cpu(cpu) { + topology_id = setup_acpi_cpu_topology(cpu, 0); + if (topology_id < 0) + return topology_id; + + if (is_threaded) { + cpu_topology[cpu].thread_id = topology_id; + topology_id = setup_acpi_cpu_topology(cpu, 1); + cpu_topology[cpu].core_id = topology_id; + topology_id = setup_acpi_cpu_topology(cpu, 2); + cpu_topology[cpu].cluster_id = topology_id; + topology_id = setup_acpi_cpu_topology(cpu, max_topo); + cpu_topology[cpu].package_id = topology_id; + } else { + cpu_topology[cpu].thread_id = -1; + cpu_topology[cpu].core_id = topology_id; + topology_id = setup_acpi_cpu_topology(cpu, 1); + cpu_topology[cpu].cluster_id = topology_id; + topology_id = setup_acpi_cpu_topology(cpu, max_topo); + cpu_topology[cpu].package_id = topology_id; + } + } + return 0; +} + +#else +static int __init parse_acpi_topology(void) +{ + /*ACPI kernels should be built with PPTT support*/ + return -EINVAL; +} +#endif + void __init init_cpu_topology(void) { reset_cpu_topology(); @@ -312,6 +362,8 @@ void __init init_cpu_topology(void) * Discard anything that was parsed if we hit an error so we * don't use partial information. */ - if (of_have_populated_dt() && parse_dt_topology()) + if ((!acpi_disabled) && parse_acpi_topology()) + reset_cpu_topology(); + else if (of_have_populated_dt() && parse_dt_topology()) reset_cpu_topology(); } diff --git a/include/linux/topology.h b/include/linux/topology.h index 4660749a7303..cbf2fb13bf92 100644 --- a/include/linux/topology.h +++ b/include/linux/topology.h @@ -43,6 +43,7 @@ if (nr_cpus_node(node)) int arch_update_cpu_topology(void); +int setup_acpi_cpu_topology(unsigned int cpu, int level); /* Conform to ACPI 2.0 SLIT distance definitions */ #define LOCAL_DISTANCE 10
Propagate the topology information from the PPTT tree to the cpu_topology array. We can get the thread id, core_id and cluster_id by assuming certain levels of the PPTT tree correspond to those concepts. The package_id is flagged in the tree and can be found by passing an arbitrary large level to setup_acpi_cpu_topology() which terminates its search when it finds an ACPI node flagged as the physical package. If the tree doesn't contain enough levels to represent all of thread/core/cod/package then the package id will be used for the missing levels. Since server/ACPI machines are more likely to be multisocket and NUMA, this patch also modifies the default clusters=sockets behavior for ACPI machines to sockets=sockets. DT machines continue to represent sockets as clusters. For ACPI machines, this results in a more normalized view of the topology. Cluster level scheduler decisions are still being made due to the "MC" level in the scheduler which has knowledge of cache sharing domains. This code is loosely based on a combination of code from: Xiongfeng Wang <wangxiongfeng2@huawei.com> John Garry <john.garry@huawei.com> Jeffrey Hugo <jhugo@codeaurora.org> Signed-off-by: Jeremy Linton <jeremy.linton@arm.com> --- arch/arm64/kernel/topology.c | 54 +++++++++++++++++++++++++++++++++++++++++++- include/linux/topology.h | 1 + 2 files changed, 54 insertions(+), 1 deletion(-) -- 2.13.5