selftests/bpf: add comparison mode to veristat
Add ability to compare and contrast two veristat runs, previously recorded with veristat using CSV output format. When veristat is called with -C (--compare) flag, veristat expects exactly two input files specified, both should be in CSV format. Expectation is that it's output from previous veristat runs, but as long as column names and formats match, it should just work. First CSV file is designated as a "baseline" provided, and the second one is comparison (experiment) data set. Establishing baseline matters later when calculating difference percentages, see below. Veristat parses these two CSV files and "reconstructs" verifier stats (it could be just a subset of all possible stats). File and program names are mandatory as they are used as joining key (these two "stats" are designated as "key stats" in the code). Veristat currently enforces that the set of stats recorded in both CSV has to exactly match, down to exact order. This is just a simplifying condition which can be lifted with a bit of additional pre-processing to reorded stat specs internally, which I didn't bother doing, yet. For all the non-key stats, veristat will output three columns: one for baseline data, one for comparison data, and one with an absolute and relative percentage difference. If either baseline or comparison values are missing (that is, respective CSV file doesn't have a row with *exactly* matching file and program name), those values are assumed to be empty or zero. In such case relative percentages are forced to +100% or -100% output, for consistency with a typical case. Veristat's -e (--emit) and -s (--sort) specs still apply, so even if CSV contains lots of stats, user can request to compare only a subset of them (and specify desired column order as well). Similarly, both CSV and human-readable table output is honored. Note that input is currently always expected to be CSV. Here's an example shell session, recording data for biosnoop tool on two different kernels and comparing them afterwards, outputting data in table format. # on slightly older production kernel $ sudo ./veristat biosnoop_bpf.o File Program Verdict Duration (us) Total insns Total states Peak states -------------- ------------------------ ------- ------------- ----------- ------------ ----------- biosnoop_bpf.o blk_account_io_merge_bio success 37 24 1 1 biosnoop_bpf.o blk_account_io_start failure 0 0 0 0 biosnoop_bpf.o block_rq_complete success 76 104 6 6 biosnoop_bpf.o block_rq_insert success 83 85 7 7 biosnoop_bpf.o block_rq_issue success 79 85 7 7 -------------- ------------------------ ------- ------------- ----------- ------------ ----------- Done. Processed 1 object files, 5 programs. $ sudo ./veristat ~/local/tmp/fbcode-bpf-objs/biosnoop_bpf.o -o csv > baseline.csv $ cat baseline.csv file_name,prog_name,verdict,duration,total_insns,total_states,peak_states biosnoop_bpf.o,blk_account_io_merge_bio,success,36,24,1,1 biosnoop_bpf.o,blk_account_io_start,failure,0,0,0,0 biosnoop_bpf.o,block_rq_complete,success,82,104,6,6 biosnoop_bpf.o,block_rq_insert,success,78,85,7,7 biosnoop_bpf.o,block_rq_issue,success,74,85,7,7 # on latest bpf-next kernel $ sudo ./veristat biosnoop_bpf.o File Program Verdict Duration (us) Total insns Total states Peak states -------------- ------------------------ ------- ------------- ----------- ------------ ----------- biosnoop_bpf.o blk_account_io_merge_bio success 31 24 1 1 biosnoop_bpf.o blk_account_io_start failure 0 0 0 0 biosnoop_bpf.o block_rq_complete success 76 104 6 6 biosnoop_bpf.o block_rq_insert success 83 91 7 7 biosnoop_bpf.o block_rq_issue success 74 91 7 7 -------------- ------------------------ ------- ------------- ----------- ------------ ----------- Done. Processed 1 object files, 5 programs. $ sudo ./veristat biosnoop_bpf.o -o csv > comparison.csv $ cat comparison.csv file_name,prog_name,verdict,duration,total_insns,total_states,peak_states biosnoop_bpf.o,blk_account_io_merge_bio,success,71,24,1,1 biosnoop_bpf.o,blk_account_io_start,failure,0,0,0,0 biosnoop_bpf.o,block_rq_complete,success,82,104,6,6 biosnoop_bpf.o,block_rq_insert,success,83,91,7,7 biosnoop_bpf.o,block_rq_issue,success,87,91,7,7 # now let's compare with human-readable output (note that no sudo needed) # we also ignore verification duration in this case to shortned output $ ./veristat -C baseline.csv comparison.csv -e file,prog,verdict,insns File Program Verdict (A) Verdict (B) Verdict (DIFF) Total insns (A) Total insns (B) Total insns (DIFF) -------------- ------------------------ ----------- ----------- -------------- --------------- --------------- ------------------ biosnoop_bpf.o blk_account_io_merge_bio success success MATCH 24 24 +0 (+0.00%) biosnoop_bpf.o blk_account_io_start failure failure MATCH 0 0 +0 (+100.00%) biosnoop_bpf.o block_rq_complete success success MATCH 104 104 +0 (+0.00%) biosnoop_bpf.o block_rq_insert success success MATCH 91 85 -6 (-6.59%) biosnoop_bpf.o block_rq_issue success success MATCH 91 85 -6 (-6.59%) -------------- ------------------------ ----------- ----------- -------------- --------------- --------------- ------------------ While not particularly exciting example (it turned out to be kind of hard to quickly find a nice example with significant difference just because of kernel version bump), it should demonstrate main features. Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/r/20220921164254.3630690-4-andrii@kernel.orgSigned-off-by: Alexei Starovoitov <ast@kernel.org>
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