Re: [PATCH] Document Linux's memory barriers [try #2]

Jesse Barnes
2006-03-09T00:59:22Z

On Wednesday, March 8, 2006 4:37 pm, Paul Mackerras wrote:
> Matthew Wilcox writes:
> > Looking at the SGI implementation, it's smarter than you think.
> > Looks like there's a register in the local I/O hub that lets you
> > determine when this write has been queued in the appropriate
> > host->pci bridge.
>
> Given that mmiowb takes no arguments, how does it know which is the
> appropriate PCI host bridge?

It uses a per-node address space to reference the local bridge. The
local bridge then waits until the remote bridge has acked the write
before, then sets the outstanding write register to the appropriate
value.

Jesse