From c46bf3bd00167e09729f884dd479b0a8d1a63f95 Mon Sep 17 00:00:00 2001 From: Namhyung Kim Date: Tue, 14 Mar 2023 16:42:37 -0700 Subject: [PATCH] perf record: Update documentation for BPF filters Add more description and examples. Signed-off-by: Namhyung Kim Cc: Adrian Hunter Cc: Andi Kleen Cc: Hao Luo Cc: Ian Rogers Cc: Ingo Molnar Cc: James Clark Cc: Jiri Olsa Cc: Kan Liang Cc: Leo Yan Cc: Peter Zijlstra Cc: Ravi Bangoria Cc: Song Liu Cc: Stephane Eranian Cc: bpf@vger.kernel.org Link: https://lore.kernel.org/r/20230314234237.3008956-2-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo --- 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 122f717..680396c 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: + + (("," | "||") )* + + The 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 can be one of: + ==, !=, >, >=, <, <=, & + + The can be one of: + (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 -- 2.7.4