perf-diff(1) ============ NAME ---- perf-diff - Read perf.data files and display the differential profile SYNOPSIS -------- [verse] 'perf diff' [baseline file] [data file1] [[data file2] ... ] DESCRIPTION ----------- This command displays the performance difference amongst two or more perf.data files captured via perf record. If no parameters are passed it will assume perf.data.old and perf.data. The differential profile is displayed only for events matching both specified perf.data files. If no parameters are passed the samples will be sorted by dso and symbol. As the perf.data files could come from different binaries, the symbols addresses could vary. So perf diff is based on the comparison of the files and symbols name. OPTIONS ------- -D:: --dump-raw-trace:: Dump raw trace in ASCII. --kallsyms=:: kallsyms pathname -m:: --modules:: Load module symbols. WARNING: use only with -k and LIVE kernel -d:: --dsos=:: Only consider symbols in these dsos. CSV that understands file://filename entries. This option will affect the percentage of the Baseline/Delta column. See --percentage for more info. -C:: --comms=:: Only consider symbols in these comms. CSV that understands file://filename entries. This option will affect the percentage of the Baseline/Delta column. See --percentage for more info. -S:: --symbols=:: Only consider these symbols. CSV that understands file://filename entries. This option will affect the percentage of the Baseline/Delta column. See --percentage for more info. -s:: --sort=:: Sort by key(s): pid, comm, dso, symbol, cpu, parent, srcline. Please see description of --sort in the perf-report man page. -t:: --field-separator=:: Use a special separator character and don't pad with spaces, replacing all occurrences of this separator in symbol names (and other output) with a '.' character, that thus it's the only non valid separator. -v:: --verbose:: Be verbose, for instance, show the raw counts in addition to the diff. -f:: --force:: Don't do ownership validation. --symfs=:: Look for files with symbols relative to this directory. -b:: --baseline-only:: Show only items with match in baseline. -c:: --compute:: Differential computation selection - delta,ratio,wdiff (default is delta). See COMPARISON METHODS section for more info. -p:: --period:: Show period values for both compared hist entries. -F:: --formula:: Show formula for given computation. -o:: --order:: Specify compute sorting column number. --percentage:: Determine how to display the overhead percentage of filtered entries. Filters can be applied by --comms, --dsos and/or --symbols options. "relative" means it's relative to filtered entries only so that the sum of shown entries will be always 100%. "absolute" means it retains the original value before and after the filter is applied. COMPARISON ---------- The comparison is governed by the baseline file. The baseline perf.data file is iterated for samples. All other perf.data files specified on the command line are searched for the baseline sample pair. If the pair is found, specified computation is made and result is displayed. All samples from non-baseline perf.data files, that do not match any baseline entry, are displayed with empty space within baseline column and possible computation results (delta) in their related column. Example files samples: - file A with samples f1, f2, f3, f4, f6 - file B with samples f2, f4, f5 - file C with samples f1, f2, f5 Example output: x - computation takes place for pair b - baseline sample percentage - perf diff A B C baseline/A compute/B compute/C samples --------------------------------------- b x f1 b x x f2 b f3 b x f4 b f6 x x f5 - perf diff B A C baseline/B compute/A compute/C samples --------------------------------------- b x x f2 b x f4 b x f5 x x f1 x f3 x f6 - perf diff C B A baseline/C compute/B compute/A samples --------------------------------------- b x f1 b x x f2 b x f5 x f3 x x f4 x f6 COMPARISON METHODS ------------------ delta ~~~~~ If specified the 'Delta' column is displayed with value 'd' computed as: d = A->period_percent - B->period_percent with: - A/B being matching hist entry from data/baseline file specified (or perf.data/perf.data.old) respectively. - period_percent being the % of the hist entry period value within single data file - with filtering by -C, -d and/or -S, period_percent might be changed relative to how entries are filtered. Use --percentage=absolute to prevent such fluctuation. ratio ~~~~~ If specified the 'Ratio' column is displayed with value 'r' computed as: r = A->period / B->period with: - A/B being matching hist entry from data/baseline file specified (or perf.data/perf.data.old) respectively. - period being the hist entry period value wdiff:WEIGHT-B,WEIGHT-A ~~~~~~~~~~~~~~~~~~~~~~~ If specified the 'Weighted diff' column is displayed with value 'd' computed as: d = B->period * WEIGHT-A - A->period * WEIGHT-B - A/B being matching hist entry from data/baseline file specified (or perf.data/perf.data.old) respectively. - period being the hist entry period value - WEIGHT-A/WEIGHT-B being user supplied weights in the the '-c' option behind ':' separator like '-c wdiff:1,2'. - WEIGHT-A being the weight of the data file - WEIGHT-B being the weight of the baseline data file SEE ALSO -------- linkperf:perf-record[1], linkperf:perf-report[1] online subsystems before cgroup_name/path() are operational
While refactoring cgroup creation, a5bca2152036 ("cgroup: factor out cgroup_create() out of cgroup_mkdir()") incorrectly onlined subsystems before the new cgroup is associated with it kernfs_node. This is fine for cgroup proper but cgroup_name/path() depend on the associated kernfs_node and if a subsystem makes the new cgroup_subsys_state visible, which they're allowed to after onlining, it can lead to NULL dereference. The current code performs cgroup creation and subsystem onlining in cgroup_create() and cgroup_mkdir() makes the cgroup and subsystems visible afterwards. There's no reason to online the subsystems early and we can simply drop cgroup_apply_control_enable() call from cgroup_create() so that the subsystems are onlined and made visible at the same time. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Fixes: a5bca2152036 ("cgroup: factor out cgroup_create() out of cgroup_mkdir()") Cc: stable@vger.kernel.org # v4.6+
Diffstat (limited to 'include/uapi/asm-generic/errno.h')