Messages in this thread | | | From | kan.liang@linux ... | Subject | [PATCH 0/4] perf: Fix the ctx->pmu for a hybrid system | Date | Wed, 16 Jun 2021 11:55:30 -0700 |
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From: Kan Liang <kan.liang@linux.intel.com>
The patchset is to fix the below WARNING triggered on an ADL machine when a user enables per-task monitoring with all available perf_hw_context PMUs.
WARNING: CPU: 8 PID: 37107 at arch/x86/events/core.c:1505 x86_pmu_start+0x77/0x90 Call Trace: x86_pmu_enable+0x111/0x2f0 event_sched_in+0x167/0x230 merge_sched_in+0x1a7/0x3d0 visit_groups_merge.constprop.0.isra.0+0x16f/0x450 ? x86_pmu_del+0x42/0x190 ctx_sched_in+0xb8/0x170 perf_event_sched_in+0x61/0x90 __perf_event_task_sched_in+0x20b/0x2a0 finish_task_switch.isra.0+0x16a/0x290 __schedule+0x2fd/0x970 ? free_inode_nonrcu+0x18/0x20 schedule+0x4f/0xc0 do_wait+0x176/0x2f0 kernel_wait4+0xaf/0x150
Here is the line of the WARNING. if (WARN_ON_ONCE(!(event->hw.state & PERF_HES_STOPPED)))
To fix the issue, the generic perf codes have to understand the supported CPU mask of a specific hybrid PMU. So it can update the ctx->pmu accordingly, when a task is scheduled on a CPU which has a different type of PMU from the previous CPU. The supported_cpus has to be moved to the struct pmu.
Besides, the moving can bring another improvement. All hybrid architectures including x86 and arm check whether an event is schedulable on the current CPU via the filter_match callback. Since the supported_cpus is moved to struct pmu, the check can be done in the generic code. The filter_match callback may be avoided. The patchset only implements the improvement for x86. Arm may implement a similar improvement later separately.
Kan Liang (4): perf: Update the ctx->pmu for a hybrid system perf/x86: Fix the x86_pmu_start WARNING on a hybrid system perf: Check the supported CPU of an event perf/x86: Remove filter_match callback
arch/x86/events/core.c | 22 ++++------------------ arch/x86/events/intel/core.c | 19 ++++--------------- arch/x86/events/perf_event.h | 2 -- include/linux/perf_event.h | 7 +++++++ kernel/events/core.c | 39 ++++++++++++++++++++++++++++++++++++++- 5 files changed, 53 insertions(+), 36 deletions(-)
-- 2.7.4
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