lkml.org 
[lkml]   [2004]   [May]   [24]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: scheduler: IRQs disabled over context switches
On Mon, 24 May 2004, Ingo Molnar wrote:

>
> * Davide Libenzi <davidel@xmailserver.org> wrote:
>
> > We used to do it in 2.4. What changed to make it fragile? The
> > threading (TLS) thing?
>
> it _should_ work, but in the past we only had trouble from such changes
> (at least in the O(1) tree of scheduling - 2.4 scheduler is OK.). We
> could try the patch below. It certainly boots on SMP x86. But it causes
> a 3.5% slowdown in lat_ctx so i'd not do it unless there are some really
> good reasons.

IMO it is fine, as long as it works with IRQ disabled. There are archs
where IRQ latencies matters more than lat_ctx times (that BTW are bogus).
And we already have the infrastructure in place to let the arch to choose
the way better fits it. Russel reported that a guy trying it (IRQ enabled
ctx switch) with MIPS was having some problem with it though.


BTW, the unlock_irq should go in prepare not finish.


- Davide

-
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 14:03    [from the cache]
©2003-2011 Jasper Spaans