I think the user/OS instruction counts are subject to a lot of factors.
The 'init' process on Linux for instance is user-level. I'm not sure if
there is an analogue on Solaris or not, but relying on instruction
counts is not a good idea anyway for multiprocessor systems, since
multiprocessors will often experience entirely different execution paths
from run to run.
Zhang Yu wrote:
I only care the number of instructions from the user. pstats gives two
kind of instruction count, one is from the user and the other is from
the supervisor, I guess the OS idle loop may increase the instruction
counts of the supervisor but will not impact that of the user.
Thanks,
Yu
On Jan 29, 2008 1:47 PM, Dan Gibson <degibson@xxxxxxxx
<mailto:degibson@xxxxxxxx>> wrote:
Processors will always execute SOME code somewhere -- pstats is
agnostic
to which code is executed. That is, even the execution of the OS idle
loop will cause the pstats instruction counts to increment-- you
cannot
assume processors that you do not assign tasks do not execute
instructions.
Zhang Yu wrote:
> Thanks for the reply. However, what I mean of pstats is already a
> delta of the instructions (I did the calculation myself). And in my
> case, the number of instructions executed by each processor
should not
> be equal or similar.
>
> Yu
>
> On Jan 29, 2008 12:15 PM, Dan Gibson <degibson@xxxxxxxx
<mailto:degibson@xxxxxxxx>
> <mailto:degibson@xxxxxxxx <mailto:degibson@xxxxxxxx>>> wrote:
>
> The number of instructions reported by ruby is a delta
between the
> initial instruction count and the final instruction count. The
> number of
> instructions reported by pstats is a total instruction count,
> staring at
> boot-time if I am not mistaken. Hence the discrepancy.
>
> Zhang Yu wrote:
> > Hi,
> >
> > I'm using Gems2.0 with Simics3.0.30. While I run the
simulation with
> > multiple cores, the statistics dumped by ruby seems to be
> > unreasonable. For example, when I use "taskset" command to
assign a
> > single task to a certain processor, instruction_executed
for all the
> > processors are almost the same in the ruby statistics.
However, if I
> > use "pstats" command in simics, I can see obviously that
the certain
> > processor executed much more instructions than other
processors. So,
> > is there anything I can do to make the ruby stats seems more
> reasonable?
> >
> > Thanks,
> > Yu
> >
>
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