Re: [PATCH] speed up SATA

Jeff Garzik
2004-03-30T17:43:10Z

Marc Bevand wrote:
> I think I am reaching the physical limit of the PCI bus (theoretically it
> would be 133 MB/s or 133000 blocks/s). When setting the PCI latency
> timer of
> the SiI3114 controller to 240 (was 64), I am able to reach 100000 blocks/s.

That's interesting.

I wonder if we should look at making pci_set_master()'s latency timer
setting code be a bit smarter.

It (pcibios_set_master in arch/i386/pci/i386.c) current checks the
latency timer value programmed by the BIOS. If the BIOS did not
initialize the value, then it is set to 64. Otherwise, it is clamped to
the maximum 255.

I wonder if your BIOS shouldn't increase that latency timer value...?

Jeff