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author | Linus Torvalds <torvalds@linux-foundation.org> | 2020-08-03 14:58:38 -0700 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2020-08-03 14:58:38 -0700 |
commit | e4cbce4d131753eca271d9d67f58c6377f27ad21 (patch) | |
tree | e08e3c8836cd7b9f800e209131aed70897f5fe07 /arch | |
parent | b34133fec882d2717f2d61a2a010edd3422368c8 (diff) | |
parent | 949bcb8135a96a6923e676646bd29cbe69e8350f (diff) | |
download | lwn-e4cbce4d131753eca271d9d67f58c6377f27ad21.tar.gz lwn-e4cbce4d131753eca271d9d67f58c6377f27ad21.zip |
Merge tag 'sched-core-2020-08-03' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler updates from Ingo Molnar:
- Improve uclamp performance by using a static key for the fast path
- Add the "sched_util_clamp_min_rt_default" sysctl, to optimize for
better power efficiency of RT tasks on battery powered devices.
(The default is to maximize performance & reduce RT latencies.)
- Improve utime and stime tracking accuracy, which had a fixed boundary
of error, which created larger and larger relative errors as the
values become larger. This is now replaced with more precise
arithmetics, using the new mul_u64_u64_div_u64() helper in math64.h.
- Improve the deadline scheduler, such as making it capacity aware
- Improve frequency-invariant scheduling
- Misc cleanups in energy/power aware scheduling
- Add sched_update_nr_running tracepoint to track changes to nr_running
- Documentation additions and updates
- Misc cleanups and smaller fixes
* tag 'sched-core-2020-08-03' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (54 commits)
sched/doc: Factorize bits between sched-energy.rst & sched-capacity.rst
sched/doc: Document capacity aware scheduling
sched: Document arch_scale_*_capacity()
arm, arm64: Fix selection of CONFIG_SCHED_THERMAL_PRESSURE
Documentation/sysctl: Document uclamp sysctl knobs
sched/uclamp: Add a new sysctl to control RT default boost value
sched/uclamp: Fix a deadlock when enabling uclamp static key
sched: Remove duplicated tick_nohz_full_enabled() check
sched: Fix a typo in a comment
sched/uclamp: Remove unnecessary mutex_init()
arm, arm64: Select CONFIG_SCHED_THERMAL_PRESSURE
sched: Cleanup SCHED_THERMAL_PRESSURE kconfig entry
arch_topology, sched/core: Cleanup thermal pressure definition
trace/events/sched.h: fix duplicated word
linux/sched/mm.h: drop duplicated words in comments
smp: Fix a potential usage of stale nr_cpus
sched/fair: update_pick_idlest() Select group with lowest group_util when idle_cpus are equal
sched: nohz: stop passing around unused "ticks" parameter.
sched: Better document ttwu()
sched: Add a tracepoint to track rq->nr_running
...
Diffstat (limited to 'arch')
-rw-r--r-- | arch/arm/include/asm/topology.h | 3 | ||||
-rw-r--r-- | arch/arm64/include/asm/topology.h | 3 | ||||
-rw-r--r-- | arch/x86/include/asm/div64.h | 14 | ||||
-rw-r--r-- | arch/x86/include/asm/topology.h | 2 | ||||
-rw-r--r-- | arch/x86/kernel/smpboot.c | 50 |
5 files changed, 58 insertions, 14 deletions
diff --git a/arch/arm/include/asm/topology.h b/arch/arm/include/asm/topology.h index 435aba289fc5..e0593cf095d0 100644 --- a/arch/arm/include/asm/topology.h +++ b/arch/arm/include/asm/topology.h @@ -16,8 +16,9 @@ /* Enable topology flag updates */ #define arch_update_cpu_topology topology_update_cpu_topology -/* Replace task scheduler's default thermal pressure retrieve API */ +/* Replace task scheduler's default thermal pressure API */ #define arch_scale_thermal_pressure topology_get_thermal_pressure +#define arch_set_thermal_pressure topology_set_thermal_pressure #else diff --git a/arch/arm64/include/asm/topology.h b/arch/arm64/include/asm/topology.h index 0cc835ddfcd1..e042f6527981 100644 --- a/arch/arm64/include/asm/topology.h +++ b/arch/arm64/include/asm/topology.h @@ -34,8 +34,9 @@ void topology_scale_freq_tick(void); /* Enable topology flag updates */ #define arch_update_cpu_topology topology_update_cpu_topology -/* Replace task scheduler's default thermal pressure retrieve API */ +/* Replace task scheduler's default thermal pressure API */ #define arch_scale_thermal_pressure topology_get_thermal_pressure +#define arch_set_thermal_pressure topology_set_thermal_pressure #include <asm-generic/topology.h> diff --git a/arch/x86/include/asm/div64.h b/arch/x86/include/asm/div64.h index 9b8cb50768c2..b8f1dc0761e4 100644 --- a/arch/x86/include/asm/div64.h +++ b/arch/x86/include/asm/div64.h @@ -74,16 +74,26 @@ static inline u64 mul_u32_u32(u32 a, u32 b) #else # include <asm-generic/div64.h> -static inline u64 mul_u64_u32_div(u64 a, u32 mul, u32 div) +/* + * Will generate an #DE when the result doesn't fit u64, could fix with an + * __ex_table[] entry when it becomes an issue. + */ +static inline u64 mul_u64_u64_div_u64(u64 a, u64 mul, u64 div) { u64 q; asm ("mulq %2; divq %3" : "=a" (q) - : "a" (a), "rm" ((u64)mul), "rm" ((u64)div) + : "a" (a), "rm" (mul), "rm" (div) : "rdx"); return q; } +#define mul_u64_u64_div_u64 mul_u64_u64_div_u64 + +static inline u64 mul_u64_u32_div(u64 a, u32 mul, u32 div) +{ + return mul_u64_u64_div_u64(a, mul, div); +} #define mul_u64_u32_div mul_u64_u32_div #endif /* CONFIG_X86_32 */ diff --git a/arch/x86/include/asm/topology.h b/arch/x86/include/asm/topology.h index 79d8d5496330..f4234575f3fd 100644 --- a/arch/x86/include/asm/topology.h +++ b/arch/x86/include/asm/topology.h @@ -193,7 +193,7 @@ static inline void sched_clear_itmt_support(void) } #endif /* CONFIG_SCHED_MC_PRIO */ -#ifdef CONFIG_SMP +#if defined(CONFIG_SMP) && defined(CONFIG_X86_64) #include <asm/cpufeature.h> DECLARE_STATIC_KEY_FALSE(arch_scale_freq_key); diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c index ffbd9a3d78d8..518ac6bf752e 100644 --- a/arch/x86/kernel/smpboot.c +++ b/arch/x86/kernel/smpboot.c @@ -56,6 +56,7 @@ #include <linux/cpuidle.h> #include <linux/numa.h> #include <linux/pgtable.h> +#include <linux/overflow.h> #include <asm/acpi.h> #include <asm/desc.h> @@ -1777,6 +1778,7 @@ void native_play_dead(void) #endif +#ifdef CONFIG_X86_64 /* * APERF/MPERF frequency ratio computation. * @@ -1975,6 +1977,7 @@ static bool core_set_max_freq_ratio(u64 *base_freq, u64 *turbo_freq) static bool intel_set_max_freq_ratio(void) { u64 base_freq, turbo_freq; + u64 turbo_ratio; if (slv_set_max_freq_ratio(&base_freq, &turbo_freq)) goto out; @@ -2000,15 +2003,23 @@ out: /* * Some hypervisors advertise X86_FEATURE_APERFMPERF * but then fill all MSR's with zeroes. + * Some CPUs have turbo boost but don't declare any turbo ratio + * in MSR_TURBO_RATIO_LIMIT. */ - if (!base_freq) { - pr_debug("Couldn't determine cpu base frequency, necessary for scale-invariant accounting.\n"); + if (!base_freq || !turbo_freq) { + pr_debug("Couldn't determine cpu base or turbo frequency, necessary for scale-invariant accounting.\n"); return false; } - arch_turbo_freq_ratio = div_u64(turbo_freq * SCHED_CAPACITY_SCALE, - base_freq); + turbo_ratio = div_u64(turbo_freq * SCHED_CAPACITY_SCALE, base_freq); + if (!turbo_ratio) { + pr_debug("Non-zero turbo and base frequencies led to a 0 ratio.\n"); + return false; + } + + arch_turbo_freq_ratio = turbo_ratio; arch_set_max_freq_ratio(turbo_disabled()); + return true; } @@ -2048,11 +2059,19 @@ static void init_freq_invariance(bool secondary) } } +static void disable_freq_invariance_workfn(struct work_struct *work) +{ + static_branch_disable(&arch_scale_freq_key); +} + +static DECLARE_WORK(disable_freq_invariance_work, + disable_freq_invariance_workfn); + DEFINE_PER_CPU(unsigned long, arch_freq_scale) = SCHED_CAPACITY_SCALE; void arch_scale_freq_tick(void) { - u64 freq_scale; + u64 freq_scale = SCHED_CAPACITY_SCALE; u64 aperf, mperf; u64 acnt, mcnt; @@ -2064,19 +2083,32 @@ void arch_scale_freq_tick(void) acnt = aperf - this_cpu_read(arch_prev_aperf); mcnt = mperf - this_cpu_read(arch_prev_mperf); - if (!mcnt) - return; this_cpu_write(arch_prev_aperf, aperf); this_cpu_write(arch_prev_mperf, mperf); - acnt <<= 2*SCHED_CAPACITY_SHIFT; - mcnt *= arch_max_freq_ratio; + if (check_shl_overflow(acnt, 2*SCHED_CAPACITY_SHIFT, &acnt)) + goto error; + + if (check_mul_overflow(mcnt, arch_max_freq_ratio, &mcnt) || !mcnt) + goto error; freq_scale = div64_u64(acnt, mcnt); + if (!freq_scale) + goto error; if (freq_scale > SCHED_CAPACITY_SCALE) freq_scale = SCHED_CAPACITY_SCALE; this_cpu_write(arch_freq_scale, freq_scale); + return; + +error: + pr_warn("Scheduler frequency invariance went wobbly, disabling!\n"); + schedule_work(&disable_freq_invariance_work); +} +#else +static inline void init_freq_invariance(bool secondary) +{ } +#endif /* CONFIG_X86_64 */ |