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While sampling for marked events, currently we record the sample only if the SIAR valid bit of Sampled Instruction Event Register (SIER) is set. SIAR_VALID bit is used for fetching the instruction address from Sampled Instruction Address Register(SIAR). But there are some usecases, where the user is interested only in the PMU stats at each counter overflow and the exact IP of the overflow event is not required. Dropping SIAR invalid samples will fail to record some of the counter overflows in such cases. Example of such usecase is dumping the PMU stats (event counts) after some regular amount of instructions/events from the userspace (ex: via ptrace). Here counter overflow is indicated to userspace via signal handler, and captured by monitoring and enabling I/O signaling on the event file descriptor. In these cases, we expect to get sample/overflow indication after each specified sample_period. Perf event attribute will not have PERF_SAMPLE_IP set in the sample_type if exact IP of the overflow event is not requested. So while profiling if SAMPLE_IP is not set, just record the counter overflow irrespective of SIAR_VALID check. Suggested-by: Michael Ellerman <mpe@ellerman.id.au> Signed-off-by: Athira Rajeev <atrajeev@linux.vnet.ibm.com> [mpe: Reflow comment and if formatting] Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/1612516492-1428-1-git-send-email-atrajeev@linux.vnet.ibm.com |
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| .. | ||
| req-gen | ||
| 8xx-pmu.c | ||
| bhrb.S | ||
| callchain.c | ||
| callchain.h | ||
| callchain_32.c | ||
| callchain_64.c | ||
| core-book3s.c | ||
| core-fsl-emb.c | ||
| e500-pmu.c | ||
| e6500-pmu.c | ||
| generic-compat-pmu.c | ||
| hv-24x7-catalog.h | ||
| hv-24x7-domains.h | ||
| hv-24x7.c | ||
| hv-24x7.h | ||
| hv-common.c | ||
| hv-common.h | ||
| hv-gpci-requests.h | ||
| hv-gpci.c | ||
| hv-gpci.h | ||
| imc-pmu.c | ||
| internal.h | ||
| isa207-common.c | ||
| isa207-common.h | ||
| Makefile | ||
| mpc7450-pmu.c | ||
| perf_regs.c | ||
| power5+-pmu.c | ||
| power5-pmu.c | ||
| power6-pmu.c | ||
| power7-events-list.h | ||
| power7-pmu.c | ||
| power8-events-list.h | ||
| power8-pmu.c | ||
| power9-events-list.h | ||
| power9-pmu.c | ||
| power10-events-list.h | ||
| power10-pmu.c | ||
| ppc970-pmu.c | ||