Force one processor with Linux

Post by Philip K. Dick
Hi
On multi-processor LINUX machines, is there a way
to force an executable run on only one
processor ?
(my application crashes on multi-processor
or hyper-threaded architectures)

Your application will always run on only a single CPU unless it's a
multi-threaded application.
Binding an application to a single CPU is usually only done to have a
positive effect on cache utilzation.

If your application crashes on multi-CPU, you most likely have buggy
hardware. There is no reason wny your application should have problems
with migrating from one CPU to another.
If it's really your application having problems with SMP, then your
program is buggy and needs fixed. Find the root cause and fix that.

--
Josef Möllers (Pinguinpfleger bei FSC)
If failure had no penalty success would not be a prize
-- T. Pratchett

Philip K. Dick

2005-12-21 10:28:31 UTC

Post by Josef Moellers

Your application will always run on only a single CPU unless it's a
multi-threaded application.
Binding an application to a single CPU is usually only done to have a
positive effect on cache utilzation.
If your application crashes on multi-CPU, you most likely have buggy
hardware. There is no reason wny your application should have problems
with migrating from one CPU to another.
If it's really your application having problems with SMP, then your
program is buggy and needs fixed. Find the root cause and fix that.

Thanks Josef

My application is multi-threaded, but does not crash on
Solaris multi-processor architectures.

Unfortunately, there are parts of the code that I cannot
change because it comes from other people (CORBA middleware)
and it is very difficult to find the problem,
that's why I asked if possible to force the application
run on one processor

Michael Heiming

2005-12-21 14:09:14 UTC

Post by Philip K. Dick
Hi
On multi-processor LINUX machines, is there a way
to force an executable run on only one
processor ?

[..]

Post by Philip K. Dick
My application is multi-threaded, but does not crash on
Solaris multi-processor architectures.
Unfortunately, there are parts of the code that I cannot
change because it comes from other people (CORBA middleware)
and it is very difficult to find the problem,
that's why I asked if possible to force the application
run on one processor

man taskset

(YMMV)

--
Michael Heiming (X-PGP-Sig > GPG-Key ID: EDD27B94)
mail: echo ***@urvzvat.qr | perl -pe 'y/a-z/n-za-m/'
#bofh excuse 309: firewall needs cooling

Kasper Dupont

2005-12-21 11:01:44 UTC

Post by Philip K. Dick
(my application crashes on multi-processor
or hyper-threaded architectures)

Then it is most likely going to crash on single
CPU machines as well, maybe not as often.

--
Kasper Dupont
Note to self: Don't try to allocate
256000 pages with GFP_KERNEL on x86.

General Schvantzkoph

2005-12-21 15:02:19 UTC

Which kernel are you running?

Philip K. Dick

2005-12-21 16:57:09 UTC

Which kernel are you running?

I run on kernel 2.6, so that I can use
'taskset' (package utils/schedutils)
and my application crashes no more !

MANY THANKS TO ALL !!!

PKD

John-Paul Stewart

2005-12-21 18:13:51 UTC

Which kernel are you running?

I run on kernel 2.6, so that I can use
'taskset' (package utils/schedutils)
and my application crashes no more !

I'd take that as a pretty clear sign that there's a bug in your code! I
strongly encourage you to look into *why* you're getting crashes and fix
it so that it works without the need for 'taskset'.

linc

2005-12-22 04:03:50 UTC

Post by John-Paul Stewart

Which kernel are you running?

I run on kernel 2.6, so that I can use
'taskset' (package utils/schedutils)
and my application crashes no more !

I'd take that as a pretty clear sign that there's a bug in your code! I
strongly encourage you to look into *why* you're getting crashes and fix
it so that it works without the need for 'taskset'.

I'd take the crash as a sign that there is a bug. But if you take the
fix as a sign that there is a bug, then whatever works for you...

John-Paul Stewart

2005-12-22 16:25:38 UTC

Post by linc

Post by John-Paul Stewart

Post by Philip K. Dick
I run on kernel 2.6, so that I can use
'taskset' (package utils/schedutils)
and my application crashes no more !

I'd take that as a pretty clear sign that there's a bug in your code! I
strongly encourage you to look into *why* you're getting crashes and fix
it so that it works without the need for 'taskset'.

I'd take the crash as a sign that there is a bug. But if you take the
fix as a sign that there is a bug, then whatever works for you...

Well, I said I take *that particular fix* as a sign that the bug is in
*his* code. Sure, the crash itself is indeed a sign of a bug somewhere
(potentially even in bad hardware). The fact that it now works on the
exact same hardware with the exact same kernel and libraries strongly
suggests the bug is in his code (which now appears unable to cope with
being run on an SMP system) rather than anyplace else.

General Schvantzkoph

2005-12-21 19:53:53 UTC

Which kernel are you running?

I run on kernel 2.6, so that I can use
'taskset' (package utils/schedutils)
and my application crashes no more !
MANY THANKS TO ALL !!!
PKD

Which 2.6? There are huge differences between the different versions of
2.6. If you are running an older version of the kernel try upgrading to
the latest version, 2.6.14.4.

David Schwartz

2005-12-22 00:47:35 UTC

Post by Philip K. Dick
I run on kernel 2.6, so that I can use
'taskset' (package utils/schedutils)
and my application crashes no more !

At least it crashes much less often. I caution you that you should *NOT*
consider this code to be reliable.

By the way, you may be able to get the same effect a less drastic way.
Just make sure all your calls into the untrustworthy code come from a single
thread. Basically, you wrap their code in a service thread that makes all
the calls into it on your behalf. Think of it as a quarantine. If you can do
this in a separate process, all the better!

DS

George M. Reagan

2005-12-22 04:15:07 UTC

I really enjoyed your novel "UBIK".

Erik Max Francis

2005-12-22 04:29:32 UTC

Post by George M. Reagan
I really enjoyed your novel "UBIK".

Right, a From line indicating the name of a famous person is surely
authenaticated proof of their identity.

Not to mention Dick has been dead for over two decades.

--
Erik Max Francis && ***@alcyone.com && http://www.alcyone.com/max/
San Jose, CA, USA && 37 20 N 121 53 W && AIM erikmaxfrancis
Think twice before you speak to a friend in need.
-- Ambrose Bierce

George M. Reagan

2005-12-23 00:55:44 UTC

You OBVIOUSLY cannot take a joke.

Post by Erik Max Francis

Post by George M. Reagan
I really enjoyed your novel "UBIK".

Right, a From line indicating the name of a famous person is surely
authenaticated proof of their identity.
Not to mention Dick has been dead for over two decades.
--
San Jose, CA, USA && 37 20 N 121 53 W && AIM erikmaxfrancis
Think twice before you speak to a friend in need.
-- Ambrose Bierce

Erik Max Francis

2005-12-23 01:23:05 UTC

Post by George M. Reagan
You OBVIOUSLY cannot take a joke.

And you obviously don't realize that sarcasm doesn't come across well on
Usenet.

--
Erik Max Francis && ***@alcyone.com && http://www.alcyone.com/max/
San Jose, CA, USA && 37 20 N 121 53 W && AIM erikmaxfrancis
Custom reconciles us to everything.
-- Edmund Burke

George M. Reagan

2005-12-25 02:06:23 UTC

BLOW ME

Post by Erik Max Francis

Post by George M. Reagan
You OBVIOUSLY cannot take a joke.

And you obviously don't realize that sarcasm doesn't come across well on
Usenet.
--
San Jose, CA, USA && 37 20 N 121 53 W && AIM erikmaxfrancis
Custom reconciles us to everything.
-- Edmund Burke

Joseph2k

2006-01-31 05:17:11 UTC

Post by George M. Reagan
BLOW ME

Post by Erik Max Francis

Post by George M. Reagan
You OBVIOUSLY cannot take a joke.

And you obviously don't realize that sarcasm doesn't come across well on
Usenet.
--
San Jose, CA, USA && 37 20 N 121 53 W && AIM erikmaxfrancis
Custom reconciles us to everything.
-- Edmund Burke

Tell us where to find you so we can place the C4.

--
JosephKK
Gegen dummheit kampfen Die Gotter Selbst, vergebens.
--Shiller

James J. Dines

2006-02-02 00:28:48 UTC