Re: Measure the Accept Queueing Time

[Andi Kleen <ak at suse dot de>]

Peter Bach <peterzbach@comcast.net> writes:
 
> Most everything inside the kernel is a queue or system of queues, but
> as Frank noted, the trick is to find the proper probe points to
> measure them.


I tried to use systemtap for measuring times in the past,
but the biggest problem was that there's no good way to share
a variable between two probes (except for using globals which is racy)

So you can't nicely say

probe A
             measure time A

probe B
             measure time B
             data <<< (B-A)

Sometimes it's possible to stuff A and B into an array indexed
with the unique object the to be measured code is working on,
but in some cases that's also not possible if there isn't such 
an object.

-Andi