lkml.org 
[lkml]   [2004]   [Apr]   [8]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [parisc-linux] rmap: parisc __flush_dcache_page
From
Date
On Thu, 2004-04-08 at 13:42, Andrea Arcangeli wrote:
> What you miss is that the problem is not in flush_dcache_page, the
> problem is that the _other_ users of the prio-tree may take as long as a
> timeslice. So it's the _other_ user that you've no control about (i.e.
> truncate) that may take timeslices with irq disabled.

So the problem isn't in the parisc code, it's in the generic vm code,
OK.

> But I've an fairly optimal solution for you, you should make it a
> read_write spinlock, with the readers not disabling interrupts, and the
> writer disabling interrupts, the writer of the prio-tree will not take a
> timeslice, the readers instead will take a timeslice, but since they're
> readers and you've only to read in the flush_dcache_page irq context,
> you don't need to disable irqs for the readers. I don't have better
> solutions than this one at the moment (yeah there's the rcu reading of
> the prio-tree but I'd leave it for later...)

Yes, I'll go for that. The write need only be done on vma insert, which
should be very fast. So do we agree this is a generic solution, or were
you still thinking of trying to abstract it per-arch?

James


-
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 14:02    [W:0.085 / U:1.028 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site