Re: page fault scalability patch V12 [0/7]: Overview andperformance tests

[Benjamin Herrenschmidt]

On Thu, 2004-12-02 at 02:00 -0500, Jeff Garzik wrote:

> 
> 2.6.9:
> 	bitbang ATA taskfile registers
> 	queue_work()
> 	workqueue thread bitbangs ATA data register (read id page)
> 
> So I wonder if <something> doesn't like CPU 0 sending I/O traffic to the 
> on-board SATA PCI device, then immediately after that, CPU 1 sending I/O 
> traffic.
> 
> Anyway, back to debugging...  :)

They may not end up in order if they are stores (the stores to the
taskfile may be out of order vs; the loads/stores to/from the data
register) unless you have a spinlock protecting both or a full sync (on
ppc), but then, I don't know the ordering things on x86_64. This could
certainly be a problem on ppc & ppc64 too.

Ben.


-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/