On 22/02/2011, at 2:54, Jerome Flesch wrote:
> While investigating a timing issue with one of our program, we found out
> something weird: We've written a small test program that just calls
> clock_gettime() a lot of times and checks that the time difference between
> calls makes sense. In the
On Thursday, February 24, 2011 12:34:04 pm Andriy Gapon wrote:
> on 24/02/2011 16:18 Jerome Flesch said the following:
> > Thanks for your explanations. It helped greatly. Using ktrdump and
> > schedgraph.py
> > and after modifying our test program to set and unset automatically
> > debug.ktr.mask
on 24/02/2011 16:18 Jerome Flesch said the following:
> Thanks for your explanations. It helped greatly. Using ktrdump and
> schedgraph.py
> and after modifying our test program to set and unset automatically
> debug.ktr.mask, I've been able to get useful information.
>
> First, It made me realiz
Thanks for your explanations. It helped greatly. Using ktrdump and
schedgraph.py and after modifying our test program to set and unset
automatically debug.ktr.mask, I've been able to get useful information.
First, It made me realize that task switching, with default settings and
2 active proce
To debug weird scheduling issues I find it helpful to start by looking
at a schedgraph. schedgraph is a tool that can display a graphical
representation of what the scheduler was doing over a small slice of
time. The one downside is that you have to recompile your kernel to
get the hooks that col
Jerome Flesch wrote this message on Tue, Feb 22, 2011 at 10:22 +0100:
> We expected both processes (the test program and openssl) to have each
> half the CPU time and being scheduled quite often (at least once each
> 10ms). According to the output of our test program, it works fine for
> most of
On Feb 22, 2011, at 1:22 AM, Jerome Flesch wrote:
>> A scheduler quantum of 10ms (or HZ=100) is a common granularity; probably
>> some other process got the CPU and your timer process didn't run until the
>> next or some later scheduler tick. If you are maxing out the available CPU
>> by runnin
On Feb 21, 2011, at 8:24 AM, Jerome Flesch wrote:
While investigating a timing issue with one of our program, we found out
something weird: We've written a small test program that just calls
clock_gettime() a lot of times and checks that the time difference between
calls makes sense. In the
On Feb 21, 2011, at 8:24 AM, Jerome Flesch wrote:
> While investigating a timing issue with one of our program, we found out
> something weird: We've written a small test program that just calls
> clock_gettime() a lot of times and checks that the time difference between
> calls makes sense. In
