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)
Jagan.