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live reporting of data

live reporting of data

Posted Feb 11, 2010 9:42 UTC (Thu) by mjw (subscriber, #16740)
In reply to: Scripting support for perf by prasadkr
Parent article: Scripting support for perf

You would need pre-filtering/aggregating for that, not post-process scripting. You can do something like that with for example systemtap which filters and can aggregate values at probe point hit time, so the only data being recorded is that which is needed for the live reporting. e.g. live (top like) reporting failed syscalls with argument strings would be done by errsnoop.stp

$ stap errsnoop.stp
inotify_add_watch gdm-simple-gree  2569    2  13 (EACCES) 18, "/home/mark", 16789454
             open hald-addon-stor  2178    1 123 (ENOMEDIUM) "/dev/sdh", O_RDONLY
             open hald-addon-stor  2175    1 123 (ENOMEDIUM) "/dev/sde", O_RDONLY
             open hald-addon-stor  2177    1 123 (ENOMEDIUM) "/dev/sdg", O_RDONLY
             open hald-addon-stor  2174    1 123 (ENOMEDIUM) "/dev/sdd", O_RDONLY
             open hald-addon-stor  2176    1 123 (ENOMEDIUM) "/dev/sdf", O_RDONLY
             open        sendmail  2291    1   6 (ENXIO)  "/proc/loadavg", O_RDONLY
And you can then let it simple run to see live what silly things user space programs are doing. Some other systemtap process examples.

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