lkml.org 
[lkml]   [2002]   [Jan]   [12]   [last100]   RSS Feed
Views: [more markup]  [less markup]  [headers]  [forward] 
 
Messages in this thread
/
DateSat, 12 Jan 2002 21:53:41 +0100
FromRoman Zippel <>
SubjectRe: [2.4.17/18pre] VM and swap - it's really unusable
Hi,

Alan Cox wrote:

> So with pre-empt this happens
> 
>         driver magic
>         disable_irq(dev->irq)
> PRE-EMPT:
>         [large periods of time running other code]
> PRE-EMPT:
>         We get back and we've missed 300 packets, the serial port sharing
>         the IRQ has dropped our internet connection completely.

But it shouldn't deadlock as Victor is suggesting.

> There are numerous other examples in the kernel tree where the current code
> knows that there is a small bounded time between two actions in kernel space
> that do not have a sleep. They are not spin locked, and putting spin locks
> everywhere will just trash performance. They are pure hardware interactions
> so you can't automatically detect them.

Why should spin locks trash perfomance, while an expensive disable_irq()
doesn't?

bye, Roman
-
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 12:18    [W:0.720 / U:0.090 seconds]
©2003-2008 Jasper Spaans