lkml.org 
[lkml]   [2008]   [Jun]   [2]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: MMIO and gcc re-ordering issue
Jeremy Higdon wrote:
> We don't actually have that problem on the Altix. All writes issued
> by CPU X will be ordered with respect to each other. But writes by
> CPU X and CPU Y will not be, unless an mmiowb() is done by the
> original CPU before the second CPU writes. I.e.
>
> CPU X writel
> CPU X writel
> CPU X mmiowb
>
> CPU Y writel
> ...
>
> Note that this implies some sort of locking. Also note that if in
> the above, CPU Y did the mmiowb, that would not work.

Hmmm,

Then it's less bad than I thought - my apologies for the confusion.

Would we be able to use Ben's trick of setting a per cpu flag in
writel() then and checking that in spin unlock issuing the mmiowb()
there if needed?


Cheers,
Jes


\
 
 \ /
  Last update: 2008-06-02 11:59    [W:0.250 / U:4.520 seconds]
©2003-2017 Jasper Spaans. hosted at Digital OceanAdvertise on this site