* [PATCH RFC 1/8] perf/core: Add *group_leader to perf_event_create_kernel_counter() [not found] <20221212125844.41157-1-likexu@tencent.com> @ 2022-12-12 12:58 ` Like Xu 2022-12-12 13:23 ` Marc Zyngier 2022-12-14 3:52 ` Ravi Bangoria 0 siblings, 2 replies; 5+ messages in thread From: Like Xu @ 2022-12-12 12:58 UTC (permalink / raw) To: Peter Zijlstra, Sean Christopherson Cc: Paolo Bonzini, linux-kernel, kvm, Marc Zyngier, Fenghua Yu, kvmarm, linux-perf-users From: Like Xu <likexu@tencent.com> Like syscalls users, kernel-space perf_event creators may also use group counters abstraction to gain pmu functionalities, and an in-kernel counter groups behave much like normal 'single' counters, following the group semantics-based behavior. No functional changes at this time. An example will be that KVM creates Intel slot event as group leader and other topdown metric events to emulate MSR_PERF_METRICS pmu capability for guests. Cc: Peter Zijlstra <peterz@infradead.org> Cc: Marc Zyngier <maz@kernel.org> Cc: Fenghua Yu <fenghua.yu@intel.com> Cc: kvmarm@lists.linux.dev Cc: linux-perf-users@vger.kernel.org Signed-off-by: Like Xu <likexu@tencent.com> --- arch/arm64/kvm/pmu-emul.c | 4 ++-- arch/x86/kernel/cpu/resctrl/pseudo_lock.c | 4 ++-- arch/x86/kvm/pmu.c | 2 +- arch/x86/kvm/vmx/pmu_intel.c | 2 +- include/linux/perf_event.h | 1 + kernel/events/core.c | 4 +++- kernel/events/hw_breakpoint.c | 4 ++-- kernel/events/hw_breakpoint_test.c | 2 +- kernel/watchdog_hld.c | 2 +- 9 files changed, 14 insertions(+), 11 deletions(-) diff --git a/arch/arm64/kvm/pmu-emul.c b/arch/arm64/kvm/pmu-emul.c index 24908400e190..11c3386bc86b 100644 --- a/arch/arm64/kvm/pmu-emul.c +++ b/arch/arm64/kvm/pmu-emul.c @@ -624,7 +624,7 @@ static void kvm_pmu_create_perf_event(struct kvm_pmc *pmc) attr.sample_period = compute_period(pmc, kvm_pmu_get_pmc_value(pmc)); - event = perf_event_create_kernel_counter(&attr, -1, current, + event = perf_event_create_kernel_counter(&attr, -1, current, NULL, kvm_pmu_perf_overflow, pmc); if (IS_ERR(event)) { @@ -713,7 +713,7 @@ static struct arm_pmu *kvm_pmu_probe_armpmu(void) attr.config = ARMV8_PMUV3_PERFCTR_CPU_CYCLES; attr.sample_period = GENMASK(63, 0); - event = perf_event_create_kernel_counter(&attr, -1, current, + event = perf_event_create_kernel_counter(&attr, -1, current, NULL, kvm_pmu_perf_overflow, &attr); if (IS_ERR(event)) { diff --git a/arch/x86/kernel/cpu/resctrl/pseudo_lock.c b/arch/x86/kernel/cpu/resctrl/pseudo_lock.c index d961ae3ed96e..43e54bb200cd 100644 --- a/arch/x86/kernel/cpu/resctrl/pseudo_lock.c +++ b/arch/x86/kernel/cpu/resctrl/pseudo_lock.c @@ -952,12 +952,12 @@ static int measure_residency_fn(struct perf_event_attr *miss_attr, u64 tmp; miss_event = perf_event_create_kernel_counter(miss_attr, plr->cpu, - NULL, NULL, NULL); + NULL, NULL, NULL, NULL); if (IS_ERR(miss_event)) goto out; hit_event = perf_event_create_kernel_counter(hit_attr, plr->cpu, - NULL, NULL, NULL); + NULL, NULL, NULL, NULL); if (IS_ERR(hit_event)) goto out_miss; diff --git a/arch/x86/kvm/pmu.c b/arch/x86/kvm/pmu.c index eb594620dd75..f6c8180241d7 100644 --- a/arch/x86/kvm/pmu.c +++ b/arch/x86/kvm/pmu.c @@ -204,7 +204,7 @@ static int pmc_reprogram_counter(struct kvm_pmc *pmc, u32 type, u64 config, attr.precise_ip = 3; } - event = perf_event_create_kernel_counter(&attr, -1, current, + event = perf_event_create_kernel_counter(&attr, -1, current, NULL, kvm_perf_overflow, pmc); if (IS_ERR(event)) { pr_debug_ratelimited("kvm_pmu: event creation failed %ld for pmc->idx = %d\n", diff --git a/arch/x86/kvm/vmx/pmu_intel.c b/arch/x86/kvm/vmx/pmu_intel.c index f951dc756456..b746381307c7 100644 --- a/arch/x86/kvm/vmx/pmu_intel.c +++ b/arch/x86/kvm/vmx/pmu_intel.c @@ -299,7 +299,7 @@ int intel_pmu_create_guest_lbr_event(struct kvm_vcpu *vcpu) } event = perf_event_create_kernel_counter(&attr, -1, - current, NULL, NULL); + current, NULL, NULL, NULL); if (IS_ERR(event)) { pr_debug_ratelimited("%s: failed %ld\n", __func__, PTR_ERR(event)); diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h index 0031f7b4d9ab..5f34e1d0bff8 100644 --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -1023,6 +1023,7 @@ extern struct perf_event * perf_event_create_kernel_counter(struct perf_event_attr *attr, int cpu, struct task_struct *task, + struct perf_event *group_leader, perf_overflow_handler_t callback, void *context); extern void perf_pmu_migrate_context(struct pmu *pmu, diff --git a/kernel/events/core.c b/kernel/events/core.c index 7f04f995c975..f671b1a9a691 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -12674,12 +12674,14 @@ SYSCALL_DEFINE5(perf_event_open, * @attr: attributes of the counter to create * @cpu: cpu in which the counter is bound * @task: task to profile (NULL for percpu) + * @group_leader: event group leader * @overflow_handler: callback to trigger when we hit the event * @context: context data could be used in overflow_handler callback */ struct perf_event * perf_event_create_kernel_counter(struct perf_event_attr *attr, int cpu, struct task_struct *task, + struct perf_event *group_leader, perf_overflow_handler_t overflow_handler, void *context) { @@ -12694,7 +12696,7 @@ perf_event_create_kernel_counter(struct perf_event_attr *attr, int cpu, if (attr->aux_output) return ERR_PTR(-EINVAL); - event = perf_event_alloc(attr, cpu, task, NULL, NULL, + event = perf_event_alloc(attr, cpu, task, group_leader, NULL, overflow_handler, context, -1); if (IS_ERR(event)) { err = PTR_ERR(event); diff --git a/kernel/events/hw_breakpoint.c b/kernel/events/hw_breakpoint.c index c3797701339c..65b5b1421e62 100644 --- a/kernel/events/hw_breakpoint.c +++ b/kernel/events/hw_breakpoint.c @@ -771,7 +771,7 @@ register_user_hw_breakpoint(struct perf_event_attr *attr, void *context, struct task_struct *tsk) { - return perf_event_create_kernel_counter(attr, -1, tsk, triggered, + return perf_event_create_kernel_counter(attr, -1, tsk, NULL, triggered, context); } EXPORT_SYMBOL_GPL(register_user_hw_breakpoint); @@ -881,7 +881,7 @@ register_wide_hw_breakpoint(struct perf_event_attr *attr, cpus_read_lock(); for_each_online_cpu(cpu) { - bp = perf_event_create_kernel_counter(attr, cpu, NULL, + bp = perf_event_create_kernel_counter(attr, cpu, NULL, NULL, triggered, context); if (IS_ERR(bp)) { err = PTR_ERR(bp); diff --git a/kernel/events/hw_breakpoint_test.c b/kernel/events/hw_breakpoint_test.c index c57610f52bb4..b3597df12284 100644 --- a/kernel/events/hw_breakpoint_test.c +++ b/kernel/events/hw_breakpoint_test.c @@ -39,7 +39,7 @@ static struct perf_event *register_test_bp(int cpu, struct task_struct *tsk, int attr.bp_addr = (unsigned long)&break_vars[idx]; attr.bp_len = HW_BREAKPOINT_LEN_1; attr.bp_type = HW_BREAKPOINT_RW; - return perf_event_create_kernel_counter(&attr, cpu, tsk, NULL, NULL); + return perf_event_create_kernel_counter(&attr, cpu, tsk, NULL, NULL, NULL); } static void unregister_test_bp(struct perf_event **bp) diff --git a/kernel/watchdog_hld.c b/kernel/watchdog_hld.c index 247bf0b1582c..bb755dadba54 100644 --- a/kernel/watchdog_hld.c +++ b/kernel/watchdog_hld.c @@ -173,7 +173,7 @@ static int hardlockup_detector_event_create(void) wd_attr->sample_period = hw_nmi_get_sample_period(watchdog_thresh); /* Try to register using hardware perf events */ - evt = perf_event_create_kernel_counter(wd_attr, cpu, NULL, + evt = perf_event_create_kernel_counter(wd_attr, cpu, NULL, NULL, watchdog_overflow_callback, NULL); if (IS_ERR(evt)) { pr_debug("Perf event create on CPU %d failed with %ld\n", cpu, -- 2.38.2 ^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH RFC 1/8] perf/core: Add *group_leader to perf_event_create_kernel_counter() 2022-12-12 12:58 ` [PATCH RFC 1/8] perf/core: Add *group_leader to perf_event_create_kernel_counter() Like Xu @ 2022-12-12 13:23 ` Marc Zyngier 2022-12-15 13:11 ` Like Xu 2022-12-14 3:52 ` Ravi Bangoria 1 sibling, 1 reply; 5+ messages in thread From: Marc Zyngier @ 2022-12-12 13:23 UTC (permalink / raw) To: Like Xu Cc: Peter Zijlstra, Sean Christopherson, Paolo Bonzini, linux-kernel, kvm, Fenghua Yu, kvmarm, linux-perf-users On Mon, 12 Dec 2022 12:58:37 +0000, Like Xu <like.xu.linux@gmail.com> wrote: > > From: Like Xu <likexu@tencent.com> > > Like syscalls users, kernel-space perf_event creators may also use group > counters abstraction to gain pmu functionalities, and an in-kernel counter > groups behave much like normal 'single' counters, following the group > semantics-based behavior. > > No functional changes at this time. An example will be that KVM creates > Intel slot event as group leader and other topdown metric events to emulate > MSR_PERF_METRICS pmu capability for guests. > > Cc: Peter Zijlstra <peterz@infradead.org> > Cc: Marc Zyngier <maz@kernel.org> > Cc: Fenghua Yu <fenghua.yu@intel.com> > Cc: kvmarm@lists.linux.dev > Cc: linux-perf-users@vger.kernel.org > Signed-off-by: Like Xu <likexu@tencent.com> > --- > arch/arm64/kvm/pmu-emul.c | 4 ++-- > arch/x86/kernel/cpu/resctrl/pseudo_lock.c | 4 ++-- > arch/x86/kvm/pmu.c | 2 +- > arch/x86/kvm/vmx/pmu_intel.c | 2 +- > include/linux/perf_event.h | 1 + > kernel/events/core.c | 4 +++- > kernel/events/hw_breakpoint.c | 4 ++-- > kernel/events/hw_breakpoint_test.c | 2 +- > kernel/watchdog_hld.c | 2 +- > 9 files changed, 14 insertions(+), 11 deletions(-) > > diff --git a/arch/arm64/kvm/pmu-emul.c b/arch/arm64/kvm/pmu-emul.c > index 24908400e190..11c3386bc86b 100644 > --- a/arch/arm64/kvm/pmu-emul.c > +++ b/arch/arm64/kvm/pmu-emul.c > @@ -624,7 +624,7 @@ static void kvm_pmu_create_perf_event(struct kvm_pmc *pmc) > > attr.sample_period = compute_period(pmc, kvm_pmu_get_pmc_value(pmc)); > > - event = perf_event_create_kernel_counter(&attr, -1, current, > + event = perf_event_create_kernel_counter(&attr, -1, current, NULL, > kvm_pmu_perf_overflow, pmc); Wouldn't it be better to have a separate helper that takes the group leader as a parameter, and reimplement perf_event_create_kernel_counter() in term of this helper? M. -- Without deviation from the norm, progress is not possible. ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH RFC 1/8] perf/core: Add *group_leader to perf_event_create_kernel_counter() 2022-12-12 13:23 ` Marc Zyngier @ 2022-12-15 13:11 ` Like Xu 0 siblings, 0 replies; 5+ messages in thread From: Like Xu @ 2022-12-15 13:11 UTC (permalink / raw) To: Marc Zyngier Cc: Peter Zijlstra, Sean Christopherson, Paolo Bonzini, linux-kernel, kvm, Fenghua Yu, kvmarm, linux-perf-users On 12/12/2022 9:23 pm, Marc Zyngier wrote: > On Mon, 12 Dec 2022 12:58:37 +0000, > Like Xu <like.xu.linux@gmail.com> wrote: >> >> From: Like Xu <likexu@tencent.com> >> >> Like syscalls users, kernel-space perf_event creators may also use group >> counters abstraction to gain pmu functionalities, and an in-kernel counter >> groups behave much like normal 'single' counters, following the group >> semantics-based behavior. >> >> No functional changes at this time. An example will be that KVM creates >> Intel slot event as group leader and other topdown metric events to emulate >> MSR_PERF_METRICS pmu capability for guests. >> >> Cc: Peter Zijlstra <peterz@infradead.org> >> Cc: Marc Zyngier <maz@kernel.org> >> Cc: Fenghua Yu <fenghua.yu@intel.com> >> Cc: kvmarm@lists.linux.dev >> Cc: linux-perf-users@vger.kernel.org >> Signed-off-by: Like Xu <likexu@tencent.com> >> --- >> arch/arm64/kvm/pmu-emul.c | 4 ++-- >> arch/x86/kernel/cpu/resctrl/pseudo_lock.c | 4 ++-- >> arch/x86/kvm/pmu.c | 2 +- >> arch/x86/kvm/vmx/pmu_intel.c | 2 +- >> include/linux/perf_event.h | 1 + >> kernel/events/core.c | 4 +++- >> kernel/events/hw_breakpoint.c | 4 ++-- >> kernel/events/hw_breakpoint_test.c | 2 +- >> kernel/watchdog_hld.c | 2 +- >> 9 files changed, 14 insertions(+), 11 deletions(-) >> >> diff --git a/arch/arm64/kvm/pmu-emul.c b/arch/arm64/kvm/pmu-emul.c >> index 24908400e190..11c3386bc86b 100644 >> --- a/arch/arm64/kvm/pmu-emul.c >> +++ b/arch/arm64/kvm/pmu-emul.c >> @@ -624,7 +624,7 @@ static void kvm_pmu_create_perf_event(struct kvm_pmc *pmc) >> >> attr.sample_period = compute_period(pmc, kvm_pmu_get_pmc_value(pmc)); >> >> - event = perf_event_create_kernel_counter(&attr, -1, current, >> + event = perf_event_create_kernel_counter(&attr, -1, current, NULL, >> kvm_pmu_perf_overflow, pmc); > > Wouldn't it be better to have a separate helper that takes the group leader > as a parameter, and reimplement perf_event_create_kernel_counter() in term > of this helper? > > M. > Applied. It makes changes more concise, thank you. ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH RFC 1/8] perf/core: Add *group_leader to perf_event_create_kernel_counter() 2022-12-12 12:58 ` [PATCH RFC 1/8] perf/core: Add *group_leader to perf_event_create_kernel_counter() Like Xu 2022-12-12 13:23 ` Marc Zyngier @ 2022-12-14 3:52 ` Ravi Bangoria 2022-12-15 13:36 ` Like Xu 1 sibling, 1 reply; 5+ messages in thread From: Ravi Bangoria @ 2022-12-14 3:52 UTC (permalink / raw) To: Like Xu Cc: Peter Zijlstra, Sean Christopherson, Paolo Bonzini, linux-kernel, kvm, Marc Zyngier, Fenghua Yu, kvmarm, linux-perf-users, Ravi Bangoria > diff --git a/kernel/events/core.c b/kernel/events/core.c > index 7f04f995c975..f671b1a9a691 100644 > --- a/kernel/events/core.c > +++ b/kernel/events/core.c > @@ -12674,12 +12674,14 @@ SYSCALL_DEFINE5(perf_event_open, > * @attr: attributes of the counter to create > * @cpu: cpu in which the counter is bound > * @task: task to profile (NULL for percpu) > + * @group_leader: event group leader > * @overflow_handler: callback to trigger when we hit the event > * @context: context data could be used in overflow_handler callback > */ > struct perf_event * > perf_event_create_kernel_counter(struct perf_event_attr *attr, int cpu, > struct task_struct *task, > + struct perf_event *group_leader, > perf_overflow_handler_t overflow_handler, > void *context) > { > @@ -12694,7 +12696,7 @@ perf_event_create_kernel_counter(struct perf_event_attr *attr, int cpu, > if (attr->aux_output) > return ERR_PTR(-EINVAL); > > - event = perf_event_alloc(attr, cpu, task, NULL, NULL, > + event = perf_event_alloc(attr, cpu, task, group_leader, NULL, > overflow_handler, context, -1); Grouping involves lot of complexities. Setting group_leader won't be sufficient. Please see perf_event_open() syscall code for more detail. Thanks, Ravi ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH RFC 1/8] perf/core: Add *group_leader to perf_event_create_kernel_counter() 2022-12-14 3:52 ` Ravi Bangoria @ 2022-12-15 13:36 ` Like Xu 0 siblings, 0 replies; 5+ messages in thread From: Like Xu @ 2022-12-15 13:36 UTC (permalink / raw) To: Ravi Bangoria, Peter Zijlstra Cc: Sean Christopherson, Paolo Bonzini, linux-kernel, kvm, Marc Zyngier, Fenghua Yu, kvmarm, linux-perf-users On 14/12/2022 11:52 am, Ravi Bangoria wrote: >> diff --git a/kernel/events/core.c b/kernel/events/core.c >> index 7f04f995c975..f671b1a9a691 100644 >> --- a/kernel/events/core.c >> +++ b/kernel/events/core.c >> @@ -12674,12 +12674,14 @@ SYSCALL_DEFINE5(perf_event_open, >> * @attr: attributes of the counter to create >> * @cpu: cpu in which the counter is bound >> * @task: task to profile (NULL for percpu) >> + * @group_leader: event group leader >> * @overflow_handler: callback to trigger when we hit the event >> * @context: context data could be used in overflow_handler callback >> */ >> struct perf_event * >> perf_event_create_kernel_counter(struct perf_event_attr *attr, int cpu, >> struct task_struct *task, >> + struct perf_event *group_leader, >> perf_overflow_handler_t overflow_handler, >> void *context) >> { >> @@ -12694,7 +12696,7 @@ perf_event_create_kernel_counter(struct perf_event_attr *attr, int cpu, >> if (attr->aux_output) >> return ERR_PTR(-EINVAL); >> >> - event = perf_event_alloc(attr, cpu, task, NULL, NULL, >> + event = perf_event_alloc(attr, cpu, task, group_leader, NULL, >> overflow_handler, context, -1); > > Grouping involves lot of complexities. Setting group_leader won't be sufficient. > Please see perf_event_open() syscall code for more detail. > > Thanks, > Ravi This is the main reason why the RFC tag is added. More detailed professional reviews is encouraged. AFAI, there does exist a number of code gaps here to support grouped events in the kernel, but there are also opportunities, as there may be other new use cases bringing innovation. I have to confirm this idea with maintainers first, the alternative is to create yet another special perf_event similar to PMC_IDX_FIXED_VLBR, which schedules perf_metrics MSR for KVM stuff. PeterZ, any input ? ^ permalink raw reply [flat|nested] 5+ messages in thread
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2022-12-12 12:58 ` [PATCH RFC 1/8] perf/core: Add *group_leader to perf_event_create_kernel_counter() Like Xu
2022-12-12 13:23 ` Marc Zyngier
2022-12-15 13:11 ` Like Xu
2022-12-14 3:52 ` Ravi Bangoria
2022-12-15 13:36 ` Like Xu
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