lkml.org 
[lkml]   [2003]   [Mar]   [12]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
SubjectRe: is irq smp affinity good for anything?
From
On Tue, Mar 11, 2003 at 08:48:59PM -0500, Mark Hahn wrote:
> > I did not expect to increase global latency to these results...
> > and neither to increase latency in the CPU that's receiving
> > just one interrupt!
>
> but isn't that just a cache effect? that is, you're keeping
> all cpus busy (caches too) with user-space, so when the interrupt
> comes in, a bound interrupt has no choice, even if the cache
> is busy with userspace.
Hi

first of all thanks for your reply,

I think that user space code always has to make the best use of cache as it
can... in other words, i don't want to use a cpu exclusively for a device
that delivers 6000 ints/second

I bound an irq to a cpu because I thought that:

as spin_irq_locks just disables interrupts locally I should get better
latency that just one ISR on that particular cpu could at least reduce
a little the number of times that interrupts get disabled on that cpu

... that was my reasoning...

but latency gets worse... that's not comphrensible for me...

Ulisses


Debian GNU/Linux: a dream come true
-----------------------------------------------------------------------------
"Computers are useless. They can only give answers." Pablo Picasso

---> Visita http://www.valux.org/ para saber acerca de la <---
---> Asociación Valenciana de Usuarios de Linux <---

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-03-22 13:33    [W:0.038 / U:1.568 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site