Re: [Gems-users] instruction count


Date: Tue, 29 Jan 2008 13:55:26 -0600
From: "Zhang Yu" <thuzhangyu@xxxxxxxxx>
Subject: Re: [Gems-users] instruction count
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> 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>> 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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