From e54def4ad8144ab15f826416e2e0f290ef1901b4 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Wed, 19 Jun 2024 23:00:30 +0200 Subject: Adding upstream version 6.9.2. Signed-off-by: Daniel Baumann --- tools/perf/Documentation/tips.txt | 31 ++++++++++++++++++++++++++----- 1 file changed, 26 insertions(+), 5 deletions(-) (limited to 'tools/perf/Documentation/tips.txt') diff --git a/tools/perf/Documentation/tips.txt b/tools/perf/Documentation/tips.txt index 825745a645..67b326ba00 100644 --- a/tools/perf/Documentation/tips.txt +++ b/tools/perf/Documentation/tips.txt @@ -2,6 +2,7 @@ For a higher level overview, try: perf report --sort comm,dso Sample related events with: perf record -e '{cycles,instructions}:S' Compare performance results with: perf diff [ ] Boolean options have negative forms, e.g.: perf report --no-children +To not accumulate CPU time of children symbols add --no-children Customize output of perf script with: perf script -F event,ip,sym Generate a script for your data: perf script -g Save output of perf stat using: perf stat record @@ -12,32 +13,52 @@ List events using substring match: perf list To see list of saved events and attributes: perf evlist -v Use --symfs if your symbol files are in non-standard locations To see callchains in a more compact form: perf report -g folded +To see call chains by final symbol taking CPU time (bottom up) use perf report -G Show individual samples with: perf script Limit to show entries above 5% only: perf report --percent-limit 5 Profiling branch (mis)predictions with: perf record -b / perf report -To show assembler sample contexts use perf record -b / perf script -F +brstackinsn --xed -Treat branches as callchains: perf report --branch-history -To count events in every 1000 msec: perf stat -I 1000 -Print event counts in CSV format with: perf stat -x, +To show assembler sample context control flow use perf record -b / perf report --samples 10 and then browse context +To adjust path to source files to local file system use perf report --prefix=... --prefix-strip=... +Treat branches as callchains: perf record -b ... ; perf report --branch-history +Show estimate cycles per function and IPC in annotate use perf record -b ... ; perf report --total-cycles +To count events every 1000 msec: perf stat -I 1000 +Print event counts in machine readable CSV format with: perf stat -x\; If you have debuginfo enabled, try: perf report -s sym,srcline For memory address profiling, try: perf mem record / perf mem report For tracepoint events, try: perf report -s trace_fields To record callchains for each sample: perf record -g +If call chains don't work try perf record --call-graph dwarf or --call-graph lbr To record every process run by a user: perf record -u +To show inline functions in call traces add --inline to perf report +To not record events from perf itself add --exclude-perf Skip collecting build-id when recording: perf record -B To change sampling frequency to 100 Hz: perf record -F 100 +To show information about system the samples were collected on use perf report --header +To only collect call graph on one event use perf record -e cpu/cpu-cycles,callgraph=1/,branches ; perf report --show-ref-call-graph +To set sampling period of individual events use perf record -e cpu/cpu-cycles,period=100001/,cpu/branches,period=10001/ ... +To group events which need to be collected together for accuracy use {}: perf record -e {cycles,branches}' ... +To compute metrics for samples use perf record -e '{cycles,instructions}' ... ; perf script -F +metric See assembly instructions with percentage: perf annotate If you prefer Intel style assembly, try: perf annotate -M intel +When collecting LBR backtraces use --stitch-lbr to handle more than 32 deep entries: perf record --call-graph lbr ; perf report --stitch-lbr For hierarchical output, try: perf report --hierarchy Order by the overhead of source file name and line number: perf report -s srcline System-wide collection from all CPUs: perf record -a Show current config key-value pairs: perf config --list +To collect Processor Trace with samples use perf record -e '{intel_pt//,cycles}' ; perf script --call-trace or --insn-trace --xed -F +ipc (remove --xed if no xed) +To trace calls using Processor Trace use perf record -e intel_pt// ... ; perf script --call-trace. Then use perf script --time A-B --insn-trace to look at region of interest. +To measure approximate function latency with Processor Trace use perf record -e intel_pt// ... ; perf script --call-ret-trace +To trace only single function with Processor Trace use perf record --filter 'filter func @ program' -e intel_pt//u ./program ; perf script --insn-trace Show user configuration overrides: perf config --user --list To add Node.js USDT(User-Level Statically Defined Tracing): perf buildid-cache --add `which node` -To report cacheline events from previous recording: perf c2c report +To analyze cache line scalability issues use perf c2c record ... ; perf c2c report To browse sample contexts use perf report --sample 10 and select in context menu To separate samples by time use perf report --sort time,overhead,sym +To filter subset of samples with report or script add --time X-Y or --cpu A,B,C or --socket-filter ... To set sample time separation other than 100ms with --sort time use --time-quantum Add -I to perf record to sample register values, which will be visible in perf report sample context. To show IPC for sampling periods use perf record -e '{cycles,instructions}:S' and then browse context To show context switches in perf report sample context add --switch-events to perf record. +To show time in nanoseconds in record/report add --ns +To compare hot regions in two workloads use perf record -b -o file ... ; perf diff --stream file1 file2 +To compare scalability of two workload samples use perf diff -c ratio file1 file2 -- cgit v1.2.3