Hello,
On Wed, Nov 26, 2008 at 4:33 AM, Nagy Mostafa <[EMAIL PROTECTED]> wrote:
> Hi,
> When running pfmon in sampling mode, is there a way to know when each sample
> was taken (time, or cycle count)? Can I make pfmon print the cycle count for
> each sample.
>
> If this is not the way to go, can you please guide me to an alternative way
> of doing that ?
>
There are several ways of doing that. With the default sampling buffer
format, which
pfmon is using, each sample contains a timestamp field. That timestamp
is guaranteed
constantly increasing IF AND ONLY IF the thread remains on the same
CPU. That timestamp
is based on the TSC of the CPU.
But a better and more portable way it to specify a second event and
print the raw samples. That
method works even if the thread migrates. You would do as follows:
$ pfmon --smpl-module=compact --with-header
-emy_event,unhalted_reference_cycles --long-smpl-periods=140000
my_program
And this will generate an output similar to:
# 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
The last column shows the value of 'unhalted_reference_cycles' (your
timestamp) for each sample (one sample/line).
Coulmn 6 shows the other timestamp I was referring to, but it is not
guarantee unique across multiple CPUs.
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