Messages in this thread Patch in this message |  | | From | David Carrillo-Cisneros <> | Subject | [PATCH v3 05/46] perf/x86/intel/cmt: add per-package locks | Date | Sat, 29 Oct 2016 17:38:02 -0700 |
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Per-package locks potentially reduce the contention when compared to the system-wide approach of the previous CQM/CMT driver.
Lockdep needs lock_class_key's to be statically initialized and/or use nesting, but nesting is currently hard-coded for up to 8 levels and it's fragile to depend on lockdep internals. To circumvent this problem, statically define CMT_MAX_NR_PKGS number of lock_class_key's.
Additional details in code's comments.
Signed-off-by: David Carrillo-Cisneros <davidcc@google.com> --- arch/x86/events/intel/cmt.c | 22 ++++++++++++++++++++++ arch/x86/events/intel/cmt.h | 8 ++++++++ 2 files changed, 30 insertions(+)
diff --git a/arch/x86/events/intel/cmt.c b/arch/x86/events/intel/cmt.c index 267a9ec..f12a06b 100644 --- a/arch/x86/events/intel/cmt.c +++ b/arch/x86/events/intel/cmt.c @@ -7,6 +7,14 @@ #include "cmt.h" #include "../perf_event.h" +/* Increase as needed as Intel CPUs grow. */ +#define CMT_MAX_NR_PKGS 8 + +#ifdef CONFIG_LOCKDEP +static struct lock_class_key mutex_keys[CMT_MAX_NR_PKGS]; +static struct lock_class_key lock_keys[CMT_MAX_NR_PKGS]; +#endif + static DEFINE_MUTEX(cmt_mutex); static unsigned int cmt_l3_scale; /* cmt hw units to bytes. */ @@ -51,6 +59,12 @@ static struct pkg_data *alloc_pkg_data(int cpu) int numa_node = cpu_to_node(cpu); u16 pkgid = topology_logical_package_id(cpu); + if (pkgid >= CMT_MAX_NR_PKGS) { + pr_err("CMT_MAX_NR_PKGS of %d is insufficient for logical packages.\n", + CMT_MAX_NR_PKGS); + return ERR_PTR(-ENOSPC); + } + if (c->x86_cache_occ_scale != cmt_l3_scale) { /* 0 scale must have been converted to 1 automatically. */ if (c->x86_cache_occ_scale || cmt_l3_scale != 1) { @@ -65,9 +79,17 @@ static struct pkg_data *alloc_pkg_data(int cpu) pkgd->max_rmid = c->x86_cache_max_rmid; + mutex_init(&pkgd->mutex); + raw_spin_lock_init(&pkgd->lock); + pkgd->work_cpu = cpu; pkgd->pkgid = pkgid; +#ifdef CONFIG_LOCKDEP + lockdep_set_class(&pkgd->mutex, &mutex_keys[pkgid]); + lockdep_set_class(&pkgd->lock, &lock_keys[pkgid]); +#endif + __min_max_rmid = min(__min_max_rmid, pkgd->max_rmid); return pkgd; diff --git a/arch/x86/events/intel/cmt.h b/arch/x86/events/intel/cmt.h index 8c16797..55416db 100644 --- a/arch/x86/events/intel/cmt.h +++ b/arch/x86/events/intel/cmt.h @@ -11,11 +11,16 @@ * Rules: * - cmt_mutex: Hold for CMT init/terminate, event init/terminate, * cgroup start/stop. + * - Hold pkg->mutex and pkg->lock in _all_ active packages to traverse or + * change the monr hierarchy. + * - pkgd->lock: Hold in current package to access that pkgd's members. */ /** * struct pkg_data - Per-package CMT data. * + * @mutex: Hold when modifying this pkg_data. + * @lock: Hold to protect pmonrs in this pkg_data. * @work_cpu: CPU to run rotation and other batch jobs. * It must be in the package associated to its * instance of pkg_data. @@ -23,6 +28,9 @@ * @pkgid: The logical package id for this pkgd. */ struct pkg_data { + struct mutex mutex; + raw_spinlock_t lock; + unsigned int work_cpu; u32 max_rmid; u16 pkgid; -- 2.8.0.rc3.226.g39d4020
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