On Thu, Nov 10, 2011 at 5:10 PM, Ulf Hansson [off-list ref] wrote:

A significant increase (10-20%) in performance throughput for
USB mass storage is the reason for incrementing the value.
By some reason the USB driver allocates buffers which requires
a scattergather list to contain a lot more than 16 elements to
get optimal performance. This change sets the maximum elements
to 128.

Tests with large reads and large writes (100 MiB) show that the
throughput increase is significant for write (10% for this test)
but not for read. Tests are run on a Linux host with ext4 FS on
the gadget mass storage device. The sg-len still exceeds 16 for
the read tests but the performance gain is low or nothing.

Signed-off-by: Ulf Hansson <redacted>
Signed-off-by: Per Forlin <redacted>

Acked-by: Linus Walleij <redacted>

I will try to compile the lot of MMCI patches from Russells
tracker and test on the PB1176 once it's there...

BTW I had to do some fixup (trivial) when I applied all the
patches from the patch tracker. Hopefully Russell can do the
same, else we'll just create a pull request with all of them or
something.

Thanks,
Linus Walleij