On Mon, 12 Apr 2010, Sarah Sharp wrote: > On Sun, Apr 11, 2010 at 02:42:29PM -0400, Alan Stern wrote: > > On Sun, 11 Apr 2010, Ramya Desai wrote: > > > > > According to her, she saw ~120 entries when I change the max_sectors > > > value to 960 or 1024 in the scsi_host_template. I want to say one > > > thing here that I am testing the default usb storage driver for 960 or > > > 1024 sectors with my UASP device.When I am testing the default usb > > > storage driver with 960 max_sectors Sarah saw ~120 scatter-gather list > > > entries. > > > > > Please let me know if you need any additional information. > > > > Please run some more tests. Can you or Sarah verify that xhci-hcd > > receives a request with more than 63 scatterlist elements when the > > sg_tablesize value is 63? The value of max_sectors doesn't matter. > > In the tests I ran with the mass storage driver, setting max_sectors > didn't matter, I always only got an sglist of no more than 63 TRBs (or > 120 if I doubled the TRBS_PER_SEGMENT to 128). The four patches I > tested with are on my xhci-large-tx branch if anyone is interested. > > I never saw the mass storage driver enqueue more sg entries than > TRBS_PER_SEGMENT. It's just Ramya's driver that has this behavior. At > this point, we can't tell what he's doing without his source code. This directly contradicts Ramya's statement above: "When I am testing the default usb storage driver with 960 max_sectors Sarah saw ~120 scatter-gather list entries." Evidently the two of you need to figure out exactly what happened. More tests can't hurt... Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
