On Thu, Jan 22, 2009 at 4:46 PM, Nagy Mostafa <nagy.most...@gmail.com> wrote: > Hi Stephane, > > I am a little confused now. I thought perfmon uses TSC to timestamp samples. > For example, the pfmon command: > > $ pfmon --smpl-module=compact --with-header > -emy_event,unhalted_reference_cycles --long-smpl-periods=140000 > my_program > > gives: > > > # description of columns: > # column 1: entry number > # column 2: process id > # column 3: thread id > # column 4: cpu number > # column 5: instruction pointer > # column 6: unique timestamp > # column 7: overflowed PMD index > # column 8: event set > # column 9: initial value of overflowed PMD (sampling period) > # followed by optional sampled PMD values in command line order > # > # > 0 5854 5854 3 0x400621 0x0000002aaadf4476 17 0 > -140000 0x3363c > 1 5854 5854 3 0x400621 0x0000002aaae0b512 17 0 > -140000 0x66c78 > 2 5854 5854 3 0x400621 0x0000002aaae21813 17 0 > -140000 0x9a2bd > 3 5854 5854 3 0x400621 0x0000002aaae37a5c 17 0 > -140000 0xcd8f9 > 4 5854 5854 3 0x400621 0x0000002aaae4dc69 17 0 > -140000 0x100f3e > 5 5854 5854 3 0x400621 0x0000002aaae63e67 17 0 > -140000 0x134583 > > So, column #6 is the TSC value divided by the CPU freq (i.e. time from reset > in ns). > You mentioned a tstamp field in the sample that relies on sched_clock(). Is > that another timestamp field ? If yes, how can I display it using pfmon ? > We are talking about the same field: tstamp = sched_clock(). This is the only field. If you try to divide by CPU freq then you will likely be affected by scaling. You can lock your CPU at a fixed frequency via /sys. I think there exists a command to get/set frequency.
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