| Message ID | 20171012140028.21599-2-dietmar.eggemann@arm.com |
|---|---|
| State | Superseded |
| Headers | show |
| Series | arm: remove cpu_efficiency | expand |
Hi Dietmar, On 12 October 2017 at 16:00, Dietmar Eggemann <dietmar.eggemann@arm.com> wrote: > Remove the 'cpu_efficiency/clock-frequency dt property' based solution > to set cpu capacity which was only working for Cortex-A15/A7 arm > big.LITTLE systems. > > I.e. the 'capacity-dmips-mhz' based solution is now the only one. It is > shared between arm and arm64 and works for every big.LITTLE system no > matter which core types it consists of. > > Cc: Russell King <linux@arm.linux.org.uk> > Cc: Vincent Guittot <vincent.guittot@linaro.org> > Cc: Juri Lelli <juri.lelli@gmail.com> > Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com> > --- > arch/arm/kernel/topology.c | 132 ++------------------------------------------- > 1 file changed, 4 insertions(+), 128 deletions(-) > > diff --git a/arch/arm/kernel/topology.c b/arch/arm/kernel/topology.c > index 24ac3cab411d..15cc131ae387 100644 > --- a/arch/arm/kernel/topology.c > +++ b/arch/arm/kernel/topology.c > @@ -30,69 +30,11 @@ > #include <asm/cputype.h> > #include <asm/topology.h> > > -/* > - * cpu capacity scale management > - */ > - > -/* > - * cpu capacity table > - * This per cpu data structure describes the relative capacity of each core. > - * On a heteregenous system, cores don't have the same computation capacity > - * and we reflect that difference in the cpu_capacity field so the scheduler > - * can take this difference into account during load balance. A per cpu > - * structure is preferred because each CPU updates its own cpu_capacity field > - * during the load balance except for idle cores. One idle core is selected > - * to run the rebalance_domains for all idle cores and the cpu_capacity can be > - * updated during this sequence. > - */ > - > #ifdef CONFIG_OF > -struct cpu_efficiency { > - const char *compatible; > - unsigned long efficiency; > -}; > - > -/* > - * Table of relative efficiency of each processors > - * The efficiency value must fit in 20bit and the final > - * cpu_scale value must be in the range > - * 0 < cpu_scale < 3*SCHED_CAPACITY_SCALE/2 > - * in order to return at most 1 when DIV_ROUND_CLOSEST > - * is used to compute the capacity of a CPU. > - * Processors that are not defined in the table, > - * use the default SCHED_CAPACITY_SCALE value for cpu_scale. > - */ > -static const struct cpu_efficiency table_efficiency[] = { > - {"arm,cortex-a15", 3891}, > - {"arm,cortex-a7", 2048}, > - {NULL, }, > -}; > - > -static unsigned long *__cpu_capacity; > -#define cpu_capacity(cpu) __cpu_capacity[cpu] > - > -static unsigned long middle_capacity = 1; > -static bool cap_from_dt = true; > - > -/* > - * Iterate all CPUs' descriptor in DT and compute the efficiency > - * (as per table_efficiency). Also calculate a middle efficiency > - * as close as possible to (max{eff_i} - min{eff_i}) / 2 > - * This is later used to scale the cpu_capacity field such that an > - * 'average' CPU is of middle capacity. Also see the comments near > - * table_efficiency[] and update_cpu_capacity(). > - */ > static void __init parse_dt_topology(void) > { > - const struct cpu_efficiency *cpu_eff; > - struct device_node *cn = NULL; > - unsigned long min_capacity = ULONG_MAX; > - unsigned long max_capacity = 0; > - unsigned long capacity = 0; > - int cpu = 0; > - > - __cpu_capacity = kcalloc(nr_cpu_ids, sizeof(*__cpu_capacity), > - GFP_NOWAIT); > + struct device_node *cn; > + int cpu; > > cn = of_find_node_by_path("/cpus"); > if (!cn) { > @@ -101,9 +43,6 @@ static void __init parse_dt_topology(void) > } > > for_each_possible_cpu(cpu) { > - const u32 *rate; > - int len; > - > /* too early to use cpu->of_node */ > cn = of_get_cpu_node(cpu, NULL); > if (!cn) { > @@ -111,76 +50,15 @@ static void __init parse_dt_topology(void) > continue; > } > > - if (topology_parse_cpu_capacity(cn, cpu)) { > + if (topology_parse_cpu_capacity(cn, cpu)) > of_node_put(cn); We should call the of_node_put unconditionally to balance the of_get_cpu_node, isn't it ? Note that this problem is also present without your change > - continue; > - } > - > - cap_from_dt = false; > - > - for (cpu_eff = table_efficiency; cpu_eff->compatible; cpu_eff++) > - if (of_device_is_compatible(cn, cpu_eff->compatible)) > - break; > - > - if (cpu_eff->compatible == NULL) > - continue; > - > - rate = of_get_property(cn, "clock-frequency", &len); > - if (!rate || len != 4) { > - pr_err("%pOF missing clock-frequency property\n", cn); > - continue; > - } > - > - capacity = ((be32_to_cpup(rate)) >> 20) * cpu_eff->efficiency; > - > - /* Save min capacity of the system */ > - if (capacity < min_capacity) > - min_capacity = capacity; > - > - /* Save max capacity of the system */ > - if (capacity > max_capacity) > - max_capacity = capacity; > - > - cpu_capacity(cpu) = capacity; > } > > - /* If min and max capacities are equals, we bypass the update of the > - * cpu_scale because all CPUs have the same capacity. Otherwise, we > - * compute a middle_capacity factor that will ensure that the capacity > - * of an 'average' CPU of the system will be as close as possible to > - * SCHED_CAPACITY_SCALE, which is the default value, but with the > - * constraint explained near table_efficiency[]. > - */ > - if (4*max_capacity < (3*(max_capacity + min_capacity))) > - middle_capacity = (min_capacity + max_capacity) > - >> (SCHED_CAPACITY_SHIFT+1); > - else > - middle_capacity = ((max_capacity / 3) > - >> (SCHED_CAPACITY_SHIFT-1)) + 1; > - > - if (cap_from_dt) > - topology_normalize_cpu_scale(); > -} > - > -/* > - * Look for a customed capacity of a CPU in the cpu_capacity table during the > - * boot. The update of all CPUs is in O(n^2) for heteregeneous system but the > - * function returns directly for SMP system. > - */ > -static void update_cpu_capacity(unsigned int cpu) > -{ > - if (!cpu_capacity(cpu) || cap_from_dt) > - return; > - > - topology_set_cpu_scale(cpu, cpu_capacity(cpu) / middle_capacity); > - > - pr_info("CPU%u: update cpu_capacity %lu\n", > - cpu, topology_get_cpu_scale(NULL, cpu)); > + topology_normalize_cpu_scale(); > } > > #else > static inline void parse_dt_topology(void) {} > -static inline void update_cpu_capacity(unsigned int cpuid) {} > #endif > > /* > @@ -276,8 +154,6 @@ void store_cpu_topology(unsigned int cpuid) > > update_siblings_masks(cpuid); > > - update_cpu_capacity(cpuid); > - > pr_info("CPU%u: thread %d, cpu %d, socket %d, mpidr %x\n", > cpuid, cpu_topology[cpuid].thread_id, > cpu_topology[cpuid].core_id, > -- > 2.11.0 >
Hi Vincent, On 17/10/17 13:28, Vincent Guittot wrote: > Hi Dietmar, > > On 12 October 2017 at 16:00, Dietmar Eggemann <dietmar.eggemann@arm.com> wrote: >> Remove the 'cpu_efficiency/clock-frequency dt property' based solution >> to set cpu capacity which was only working for Cortex-A15/A7 arm >> big.LITTLE systems. >> >> I.e. the 'capacity-dmips-mhz' based solution is now the only one. It is >> shared between arm and arm64 and works for every big.LITTLE system no >> matter which core types it consists of. >> >> Cc: Russell King <linux@arm.linux.org.uk> >> Cc: Vincent Guittot <vincent.guittot@linaro.org> >> Cc: Juri Lelli <juri.lelli@gmail.com> >> Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com> [...] >> @@ -111,76 +50,15 @@ static void __init parse_dt_topology(void) >> continue; >> } >> >> - if (topology_parse_cpu_capacity(cn, cpu)) { >> + if (topology_parse_cpu_capacity(cn, cpu)) >> of_node_put(cn); > > We should call the of_node_put unconditionally to balance the > of_get_cpu_node, isn't it ? > Note that this problem is also present without your change Thanks for the review. Brendan mentioned this the other day already. I could add an additional patch to the v3 with this code change. What do you think? diff --git a/arch/arm/kernel/topology.c b/arch/arm/kernel/topology.c index 15cc131ae387..81ec42333489 100644 --- a/arch/arm/kernel/topology.c +++ b/arch/arm/kernel/topology.c @@ -41,6 +41,7 @@ static void __init parse_dt_topology(void) pr_err("No CPU information found in DT\n"); return; } + of_node_put(cn); for_each_possible_cpu(cpu) { /* too early to use cpu->of_node */ @@ -50,8 +51,8 @@ static void __init parse_dt_topology(void) continue; } - if (topology_parse_cpu_capacity(cn, cpu)) - of_node_put(cn); + topology_parse_cpu_capacity(cn, cpu); + of_node_put(cn); } topology_normalize_cpu_scale();
Hi Dietmar, On 18 October 2017 at 12:37, Dietmar Eggemann <dietmar.eggemann@arm.com> wrote: > Hi Vincent, > > On 17/10/17 13:28, Vincent Guittot wrote: >> Hi Dietmar, >> >> On 12 October 2017 at 16:00, Dietmar Eggemann <dietmar.eggemann@arm.com> wrote: >>> Remove the 'cpu_efficiency/clock-frequency dt property' based solution >>> to set cpu capacity which was only working for Cortex-A15/A7 arm >>> big.LITTLE systems. >>> >>> I.e. the 'capacity-dmips-mhz' based solution is now the only one. It is >>> shared between arm and arm64 and works for every big.LITTLE system no >>> matter which core types it consists of. >>> >>> Cc: Russell King <linux@arm.linux.org.uk> >>> Cc: Vincent Guittot <vincent.guittot@linaro.org> >>> Cc: Juri Lelli <juri.lelli@gmail.com> >>> Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com> > > [...] > >>> @@ -111,76 +50,15 @@ static void __init parse_dt_topology(void) >>> continue; >>> } >>> >>> - if (topology_parse_cpu_capacity(cn, cpu)) { >>> + if (topology_parse_cpu_capacity(cn, cpu)) >>> of_node_put(cn); >> >> We should call the of_node_put unconditionally to balance the >> of_get_cpu_node, isn't it ? >> Note that this problem is also present without your change > > Thanks for the review. Brendan mentioned this the other day already. > > I could add an additional patch to the v3 with this code change. What do > you think? The changes looks good to me > > diff --git a/arch/arm/kernel/topology.c b/arch/arm/kernel/topology.c > index 15cc131ae387..81ec42333489 100644 > --- a/arch/arm/kernel/topology.c > +++ b/arch/arm/kernel/topology.c > @@ -41,6 +41,7 @@ static void __init parse_dt_topology(void) > pr_err("No CPU information found in DT\n"); > return; > } > + of_node_put(cn); > > for_each_possible_cpu(cpu) { > /* too early to use cpu->of_node */ > @@ -50,8 +51,8 @@ static void __init parse_dt_topology(void) > continue; > } > > - if (topology_parse_cpu_capacity(cn, cpu)) > - of_node_put(cn); > + topology_parse_cpu_capacity(cn, cpu); > + of_node_put(cn); > } > > topology_normalize_cpu_scale(); > > > > > > > > > > > > > > > > >
diff --git a/arch/arm/kernel/topology.c b/arch/arm/kernel/topology.c index 24ac3cab411d..15cc131ae387 100644 --- a/arch/arm/kernel/topology.c +++ b/arch/arm/kernel/topology.c @@ -30,69 +30,11 @@ #include <asm/cputype.h> #include <asm/topology.h> -/* - * cpu capacity scale management - */ - -/* - * cpu capacity table - * This per cpu data structure describes the relative capacity of each core. - * On a heteregenous system, cores don't have the same computation capacity - * and we reflect that difference in the cpu_capacity field so the scheduler - * can take this difference into account during load balance. A per cpu - * structure is preferred because each CPU updates its own cpu_capacity field - * during the load balance except for idle cores. One idle core is selected - * to run the rebalance_domains for all idle cores and the cpu_capacity can be - * updated during this sequence. - */ - #ifdef CONFIG_OF -struct cpu_efficiency { - const char *compatible; - unsigned long efficiency; -}; - -/* - * Table of relative efficiency of each processors - * The efficiency value must fit in 20bit and the final - * cpu_scale value must be in the range - * 0 < cpu_scale < 3*SCHED_CAPACITY_SCALE/2 - * in order to return at most 1 when DIV_ROUND_CLOSEST - * is used to compute the capacity of a CPU. - * Processors that are not defined in the table, - * use the default SCHED_CAPACITY_SCALE value for cpu_scale. - */ -static const struct cpu_efficiency table_efficiency[] = { - {"arm,cortex-a15", 3891}, - {"arm,cortex-a7", 2048}, - {NULL, }, -}; - -static unsigned long *__cpu_capacity; -#define cpu_capacity(cpu) __cpu_capacity[cpu] - -static unsigned long middle_capacity = 1; -static bool cap_from_dt = true; - -/* - * Iterate all CPUs' descriptor in DT and compute the efficiency - * (as per table_efficiency). Also calculate a middle efficiency - * as close as possible to (max{eff_i} - min{eff_i}) / 2 - * This is later used to scale the cpu_capacity field such that an - * 'average' CPU is of middle capacity. Also see the comments near - * table_efficiency[] and update_cpu_capacity(). - */ static void __init parse_dt_topology(void) { - const struct cpu_efficiency *cpu_eff; - struct device_node *cn = NULL; - unsigned long min_capacity = ULONG_MAX; - unsigned long max_capacity = 0; - unsigned long capacity = 0; - int cpu = 0; - - __cpu_capacity = kcalloc(nr_cpu_ids, sizeof(*__cpu_capacity), - GFP_NOWAIT); + struct device_node *cn; + int cpu; cn = of_find_node_by_path("/cpus"); if (!cn) { @@ -101,9 +43,6 @@ static void __init parse_dt_topology(void) } for_each_possible_cpu(cpu) { - const u32 *rate; - int len; - /* too early to use cpu->of_node */ cn = of_get_cpu_node(cpu, NULL); if (!cn) { @@ -111,76 +50,15 @@ static void __init parse_dt_topology(void) continue; } - if (topology_parse_cpu_capacity(cn, cpu)) { + if (topology_parse_cpu_capacity(cn, cpu)) of_node_put(cn); - continue; - } - - cap_from_dt = false; - - for (cpu_eff = table_efficiency; cpu_eff->compatible; cpu_eff++) - if (of_device_is_compatible(cn, cpu_eff->compatible)) - break; - - if (cpu_eff->compatible == NULL) - continue; - - rate = of_get_property(cn, "clock-frequency", &len); - if (!rate || len != 4) { - pr_err("%pOF missing clock-frequency property\n", cn); - continue; - } - - capacity = ((be32_to_cpup(rate)) >> 20) * cpu_eff->efficiency; - - /* Save min capacity of the system */ - if (capacity < min_capacity) - min_capacity = capacity; - - /* Save max capacity of the system */ - if (capacity > max_capacity) - max_capacity = capacity; - - cpu_capacity(cpu) = capacity; } - /* If min and max capacities are equals, we bypass the update of the - * cpu_scale because all CPUs have the same capacity. Otherwise, we - * compute a middle_capacity factor that will ensure that the capacity - * of an 'average' CPU of the system will be as close as possible to - * SCHED_CAPACITY_SCALE, which is the default value, but with the - * constraint explained near table_efficiency[]. - */ - if (4*max_capacity < (3*(max_capacity + min_capacity))) - middle_capacity = (min_capacity + max_capacity) - >> (SCHED_CAPACITY_SHIFT+1); - else - middle_capacity = ((max_capacity / 3) - >> (SCHED_CAPACITY_SHIFT-1)) + 1; - - if (cap_from_dt) - topology_normalize_cpu_scale(); -} - -/* - * Look for a customed capacity of a CPU in the cpu_capacity table during the - * boot. The update of all CPUs is in O(n^2) for heteregeneous system but the - * function returns directly for SMP system. - */ -static void update_cpu_capacity(unsigned int cpu) -{ - if (!cpu_capacity(cpu) || cap_from_dt) - return; - - topology_set_cpu_scale(cpu, cpu_capacity(cpu) / middle_capacity); - - pr_info("CPU%u: update cpu_capacity %lu\n", - cpu, topology_get_cpu_scale(NULL, cpu)); + topology_normalize_cpu_scale(); } #else static inline void parse_dt_topology(void) {} -static inline void update_cpu_capacity(unsigned int cpuid) {} #endif /* @@ -276,8 +154,6 @@ void store_cpu_topology(unsigned int cpuid) update_siblings_masks(cpuid); - update_cpu_capacity(cpuid); - pr_info("CPU%u: thread %d, cpu %d, socket %d, mpidr %x\n", cpuid, cpu_topology[cpuid].thread_id, cpu_topology[cpuid].core_id,
Remove the 'cpu_efficiency/clock-frequency dt property' based solution to set cpu capacity which was only working for Cortex-A15/A7 arm big.LITTLE systems. I.e. the 'capacity-dmips-mhz' based solution is now the only one. It is shared between arm and arm64 and works for every big.LITTLE system no matter which core types it consists of. Cc: Russell King <linux@arm.linux.org.uk> Cc: Vincent Guittot <vincent.guittot@linaro.org> Cc: Juri Lelli <juri.lelli@gmail.com> Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com> --- arch/arm/kernel/topology.c | 132 ++------------------------------------------- 1 file changed, 4 insertions(+), 128 deletions(-) -- 2.11.0