lkml.org 
[lkml]   [2001]   [Jun]   [30]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: Bounce buffer deadlock


On Sat, 30 Jun 2001, Steve Lord wrote:

>
> > Yes. 2.4.6-pre8 fixes that (not sure if its up already).
>
> It is up.
>
> >
> > > If the fix is to avoid page_launder in these cases then the number of
> > > occurrences when an alloc_pages fails will go up.
> >
> > > I was attempting to come up with a way of making try_to_free_buffers
> > > fail on buffers which are being processed in the generic_make_request
> > > path by marking them, the problem is there is no single place to reset
> > > the state of a buffer so that try_to_free_buffers will wait for it.
> > > Doing it after the end of the loop in generic_make_request is race
> > > prone to say the least.
> >
> > I really want to fix things like this in 2.5. (ie not avoid the deadlock
> > by completly avoiding physical IO, but avoid the deadlock by avoiding
> > physical IO on the "device" which is doing the allocation)
> >
> > Could you send me your code ? No problem if it does not work at all :)
> >
>
> Well, the basic idea is simple, but I suspect the implementation might
> rapidly become historical in 2.5. Basically I added a new buffer state bit,
> although BH_Req looks like it could be cannibalized, no one appears to check
> for it (is it really dead code?).

Dunno. Ask Jens :)

> Using a flag to skip buffers in try_to_free_buffers is easy:

I was thinking more about skipping the buffers which are "owned" by the
device which is doing the allocation.

-
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 12:55    [W:0.045 / U:0.572 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site