diff options
Diffstat (limited to 'tools/perf/Documentation/perf-c2c.txt')
| -rw-r--r-- | tools/perf/Documentation/perf-c2c.txt | 16 |
1 files changed, 13 insertions, 3 deletions
diff --git a/tools/perf/Documentation/perf-c2c.txt b/tools/perf/Documentation/perf-c2c.txt index 5c5eb2def83e..856f0dfb8e5a 100644 --- a/tools/perf/Documentation/perf-c2c.txt +++ b/tools/perf/Documentation/perf-c2c.txt @@ -22,7 +22,11 @@ you to track down the cacheline contentions. On Intel, the tool is based on load latency and precise store facility events provided by Intel CPUs. On PowerPC, the tool uses random instruction sampling with thresholding feature. On AMD, the tool uses IBS op pmu (due to hardware -limitations, perf c2c is not supported on Zen3 cpus). +limitations, perf c2c is not supported on Zen3 cpus). On Arm64 it uses SPE to +sample load and store operations, therefore hardware and kernel support is +required. See linkperf:perf-arm-spe[1] for a setup guide. Due to the +statistical nature of Arm SPE sampling, not every memory operation will be +sampled. These events provide: - memory address of the access @@ -121,11 +125,17 @@ REPORT OPTIONS perf c2c record --call-graph lbr. Disabled by default. In common cases with call stack overflows, it can recreate better call stacks than the default lbr call stack - output. But this approach is not full proof. There can be cases + output. But this approach is not foolproof. There can be cases where it creates incorrect call stacks from incorrect matches. The known limitations include exception handing such as setjmp/longjmp will have calls/returns not match. +--double-cl:: + Group the detection of shared cacheline events into double cacheline + granularity. Some architectures have an Adjacent Cacheline Prefetch + feature, which causes cacheline sharing to behave like the cacheline + size is doubled. + C2C RECORD ---------- The perf c2c record command setup options related to HITM cacheline analysis @@ -333,4 +343,4 @@ Check Joe's blog on c2c tool for detailed use case explanation: SEE ALSO -------- -linkperf:perf-record[1], linkperf:perf-mem[1] +linkperf:perf-record[1], linkperf:perf-mem[1], linkperf:perf-arm-spe[1] |