Bug 16567

Summary:	Increase of performance for single threaded program after suspend on a core i7
Product:	Power Management	Reporter:	ChriS (debian00)
Component:	Hibernation/Suspend	Assignee:	power-management_other
Status:	CLOSED UNREPRODUCIBLE
Severity:	normal	CC:	rui.zhang
Priority:	P1
Hardware:	All
OS:	Linux
Kernel Version:	2.6.35	Subsystem:
Regression:	No	Bisected commit-id:

Description ChriS 2010-08-12 08:10:55 UTC

I have 

  Thinkpad W510, Core i7 Q 820  @ 1.73GHz
  Distribution: Debian (testing)
  Linux poincare 2.6.35 #1 SMP Thu Aug 12 08:59:35 CEST 2010 x86_64 GNU/Linux

On a fresh boot, the attached "add" program has the following performance:

3.54user 0.00system 0:03.57elapsed 99%CPU (0avgtext+0avgdata 2032maxresident)k
0inputs+0outputs (0major+169minor)pagefaults 0swaps

However, after I suspend (to RAM) the machine, I see a dramatic improvement in speed:

1.45user 0.00system 0:01.46elapsed 99%CPU (0avgtext+0avgdata 2032maxresident)k
0inputs+0outputs (0major+169minor)pagefaults 0swaps

It would be nice to have that performance on first boot!  Note that this is not true for multi-threaded programs (see for example the times fot the compilation of the kernel reported in bug #15559).

Comment 1 Zhang Rui 2012-01-18 02:16:57 UTC

It's great that kernel bugzilla is back.

Chris,
Can you attach the "add" program?
can you please verify if the problem still exists in the latest upstream
kernel?

Comment 2 ChriS 2012-01-20 10:06:07 UTC

> Can you attach the "add" program?

Oh, well, I thought I did!  I am afraid I do not have it anymore.

However the good thing is that I am using 3.1.4 now and I do not have the problem anymore.

Comment 3 Zhang Rui 2012-02-02 06:07:18 UTC

Okay, bug closed. Please feel free to reopen it when you run into this problem again.