[U-Boot] [PATCH] sunxi: improve throughput in the sunxi_mmc driver

Jagan Teki
2018-04-25T05:01:03Z

On Wed, Apr 25, 2018 at 1:46 AM, Tom Rini <trini@konsulko.com> wrote:
> On Tue, Apr 24, 2018 at 09:57:58PM +0200, Maxime Ripard wrote:
>> Hi Jagan,
>>
>> On Fri, Apr 06, 2018 at 11:36:59AM +0530, Jagan Teki wrote:
>> > On Wed, Apr 4, 2018 at 12:36 PM, Maxime Ripard
>> > <maxime.ripard@bootlin.com> wrote:
>> > > On Wed, Apr 04, 2018 at 12:13:01PM +0530, Jagan Teki wrote:
>> > >> On Wed, Mar 21, 2018 at 4:48 PM, Maxime Ripard
>> > >> <maxime.ripard@bootlin.com> wrote:
>> > >> > From: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
>> > >> >
>> > >> > Throughput tests have shown the sunxi_mmc driver to take over 10s to
>> > >> > read 10MB from a fast eMMC device due to excessive delays in polling
>> > >> > loops.
>> > >> >
>> > >> > This commit restructures the main polling loops to use get_timer(...)
>> > >> > to determine whether a (millisecond) timeout has expired. We choose
>> > >> > not to use the wait_bit function, as we don't need interruptability
>> > >> > with ctrl-c and have at least one case where two bits (one for an
>> > >> > error condition and another one for completion) need to be read and
>> > >> > using wait_bit would have not added to the clarity.
>> > >> >
>> > >> > The observed speedup in testing on a A31 is greater than 10x (e.g. a
>> > >> > 10MB write decreases from 9.302s to 0.884s).
>> > >>
>> > >> Fyi: I've seen significant improvement, but not 10x on A64
>> > >> (bananpi-m64) with read
>> > >>
>> > >> Before this change:
>> > >>
>> > >> => mmc dev 0
>> > >> switch to partitions #0, OK
>> > >> mmc0 is current device
>> > >> => fatload mmc 0:1 $kernel_addr_r Image
>> > >> reading Image
>> > >> 16310784 bytes read in 821 ms (18.9 MiB/s)
>> > >> => mmc dev 1
>> > >> switch to partitions #0, OK
>> > >> mmc1(part 0) is current device
>> > >> => ext4load mmc 1:1 $kernel_addr_r Image
>> > >> 16310784 bytes read in 1109 ms (14 MiB/s)
>> > >>
>> > >>
>> > >> After this change:
>> > >>
>> > >> => mmc dev 0
>> > >> switch to partitions #0, OK
>> > >> mmc0 is current device
>> > >> => fatload mmc 0:1 $kernel_addr_r Image
>> > >> 16310784 bytes read in 784 ms (19.8 MiB/s)
>> > >> => mmc dev 1
>> > >> switch to partitions #0, OK
>> > >> mmc1(part 0) is current device
>> > >> => ext4load mmc 1:1 $kernel_addr_r Image
>> > >> 16310784 bytes read in 793 ms (19.6 MiB/s)
>> > >
>> > > Yeah, the smaller the file is, the bigger the gain is. Since you have
>> > > an almost twice bigger file, the gains are probably just noise at that
>> > > point and the bottleneck starts to be your MMC.
>> >
>> > Acked-by: Jagan Teki <jagan@openedev.com>
>>
>> Jaehoon doesn't seem to reply at all, can we merge this through the
>> sunxi tree?

Applied to u-boot-sunxi/master