Messages in this thread | | | Date | Thu, 19 Oct 2023 10:31:49 -0400 | Subject | Re: [PATCH V4 4/7] perf/x86/intel: Support LBR event logging | From | "Liang, Kan" <> |
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On 2023-10-19 7:09 a.m., Peter Zijlstra wrote: > On Wed, Oct 04, 2023 at 11:40:41AM -0700, kan.liang@linux.intel.com wrote: > >> @@ -3905,6 +3915,44 @@ static int intel_pmu_hw_config(struct perf_event *event) >> if (needs_branch_stack(event) && is_sampling_event(event)) >> event->hw.flags |= PERF_X86_EVENT_NEEDS_BRANCH_STACK; >> >> + if (branch_sample_counters(event)) { >> + struct perf_event *leader, *sibling; >> + >> + if (!(x86_pmu.flags & PMU_FL_LBR_EVENT) || >> + (event->attr.config & ~INTEL_ARCH_EVENT_MASK)) >> + return -EINVAL; >> + >> + /* >> + * The event logging is not supported in the call stack mode >> + * yet, since we cannot simply flush the LBR during e.g., >> + * multiplexing. Also, there is no obvious usage with the call >> + * stack mode. Simply forbids it for now. >> + * >> + * If any events in the group enable the LBR event logging >> + * feature, the group is treated as a LBR event logging group, >> + * which requires the extra space to store the counters. >> + */ >> + leader = event->group_leader; >> + if (branch_sample_call_stack(leader)) >> + return -EINVAL; >> + leader->hw.flags |= PERF_X86_EVENT_BRANCH_COUNTERS; > > (superfluous whitespace before operator) > >> + >> + for_each_sibling_event(sibling, leader) { >> + if (branch_sample_call_stack(sibling)) >> + return -EINVAL; >> + } >> + >> + /* >> + * Only applying the PERF_SAMPLE_BRANCH_COUNTERS doesn't >> + * require any branch stack setup. >> + * Clear the bit to avoid unnecessary branch stack setup. >> + */ >> + if (0 == (event->attr.branch_sample_type & >> + ~(PERF_SAMPLE_BRANCH_PLM_ALL | >> + PERF_SAMPLE_BRANCH_COUNTERS))) >> + event->hw.flags &= ~PERF_X86_EVENT_NEEDS_BRANCH_STACK; >> + } > > Does this / should this check the number of group members vs supported > number of lbr counters?
Sure, I will add the check here for the numbers, so perf can error out earlier.
Thanks, Kan
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