Report approximated duration in milliseconds for profile nodes.

Report approximated duration in milliseconds for profile nodes.

The simple formula "ms = ticks * sampler_interval" doesn't work,
because e.g. on Linux, the actual sampling rate can be 5 times
lower than the one set up in the code. To calculate actual sampling
rate, current time is periodically queried and processed along with
actual sampling ticks count.

Committed: http://code.google.com/p/v8/source/detail?r=4427

[Søren Thygesen Gjesse, 2010-04-15 11:03:47]

LGTM

Is the actual sampling rate mostly stable or does it vary over time?

[mnaganov (inactive), 2010-04-15 11:36:46]

On 2010/04/15 11:03:47, Søren Gjesse wrote:
> LGTM
> 
> Is the actual sampling rate mostly stable or does it vary over time?

So far, I observed stable behavior (on Linux and Mac).