Jesse Barnes wrote:
Now, in hindsight, using a PIO write set test flag approach in
writeX/spin_unlock (ala powerpc) might have been a better approach, but iirc
that never came up in the discussion, probably because we were focused on PCI
posting and not uncached vs. cached ordering.
Hi
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
Pavel Machek wrote:
Still better than changing semantics of writel for _all_ drivers.
If you are really sure driver does not depend on writel order, it is
just a sed/// command, so I don't see any big code maintenance
issues...
This isn't changing the semantics for all drivers, it means it
James Bottomley wrote:
The only way to guarantee ordering in the above setup, is to either
make writel() fully ordered or adding the mmiowb()'s inbetween the two
writel's. On Altix you have to go and read from the PCI brige to
ensure all writes to it have been flushed, which is also what
Jesse Barnes wrote:
On Thursday, May 29, 2008 2:40 pm Benjamin Herrenschmidt wrote:
On Thu, 2008-05-29 at 10:47 -0400, Jes Sorensen wrote:
The only way to guarantee ordering in the above setup, is to either
make writel() fully ordered or adding the mmiowb()'s inbetween the two
writel's
Benjamin Herrenschmidt wrote:
On Thu, 2008-05-29 at 10:47 -0400, Jes Sorensen wrote:
The only way to guarantee ordering in the above setup, is to either
make writel() fully ordered or adding the mmiowb()'s inbetween the two
writel's. On Altix you have to go and read from the PCI brige to
ensure
Roland == Roland Dreier [EMAIL PROTECTED] writes:
This is a different issue. We deal with it on powerpc by having
writel set a per-cpu flag and spin_unlock() test it, and do the
barrier if needed there.
Roland Cool... I assume you do this for mutex_unlock() etc?
Roland Is there any reason
