Add more description and examples. Signed-off-by: Namhyung Kim <namhyung@xxxxxxxxxx> --- tools/perf/Documentation/perf-record.txt | 47 +++++++++++++++++++++++- 1 file changed, 46 insertions(+), 1 deletion(-) diff --git a/tools/perf/Documentation/perf-record.txt b/tools/perf/Documentation/perf-record.txt index 122f71726eaa..680396c56bd1 100644 --- a/tools/perf/Documentation/perf-record.txt +++ b/tools/perf/Documentation/perf-record.txt @@ -183,7 +183,52 @@ OPTIONS A BPF filter can access the sample data and make a decision based on the data. Users need to set an appropriate sample type to use the BPF - filter. + filter. BPF filters need root privilege. + + The sample data field can be specified in lower case letter. Multiple + filters can be separated with comma. For example, + + --filter 'period > 1000, cpu == 1' + or + --filter 'mem_op == load || mem_op == store, mem_lvl > l1' + + The former filter only accept samples with period greater than 1000 AND + CPU number is 1. The latter one accepts either load and store memory + operations but it should have memory level above the L1. Since the + mem_op and mem_lvl fields come from the (memory) data_source, it'd only + work with some events which set the data_source field. + + Also user should request to collect that information (with -d option in + the above case). Otherwise, the following message will be shown. + + $ sudo perf record -e cycles --filter 'mem_op == load' + Error: cycles event does not have PERF_SAMPLE_DATA_SRC + Hint: please add -d option to perf record. + failed to set filter "BPF" on event cycles with 22 (Invalid argument) + + Essentially the BPF filter expression is: + + <term> <operator> <value> (("," | "||") <term> <operator> <value>)* + + The <term> can be one of: + ip, id, tid, pid, cpu, time, addr, period, txn, weight, phys_addr, + code_pgsz, data_pgsz, weight1, weight2, weight3, ins_lat, retire_lat, + p_stage_cyc, mem_op, mem_lvl, mem_snoop, mem_remote, mem_lock, + mem_dtlb, mem_blk, mem_hops + + The <operator> can be one of: + ==, !=, >, >=, <, <=, & + + The <value> can be one of: + <number> (for any term) + na, load, store, pfetch, exec (for mem_op) + l1, l2, l3, l4, cxl, io, any_cache, lfb, ram, pmem (for mem_lvl) + na, none, hit, miss, hitm, fwd, peer (for mem_snoop) + remote (for mem_remote) + na, locked (for mem_locked) + na, l1_hit, l1_miss, l2_hit, l2_miss, any_hit, any_miss, walk, fault (for mem_dtlb) + na, by_data, by_addr (for mem_blk) + hops0, hops1, hops2, hops3 (for mem_hops) --exclude-perf:: Don't record events issued by perf itself. This option should follow -- 2.40.0.rc1.284.g88254d51c5-goog