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pietrushnic / rpi-dt-linux

This repository aims to handle all patches required for Raspberry Pi support in upstream Linux kernel.
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bcm2835-mmc/dma - sys CPU load difference between upstram and foundation kernel #10

Closed pietrushnic closed 9 years ago

pietrushnic commented 9 years ago

Place holder to not forget about this problem.

Upstream measures (3.17.1+bcm2385-mmc+DMA with slave_sg):

ime syncerrypi:~$ sync; time dd if=/dev/zero of=~/test.tmp bs=500K count=1024; t 
1024+0 records in
1024+0 records out
524288000 bytes (524 MB) copied, 45.6201 s, 11.5 MB/s

real    0m45.647s
user    0m0.000s
sys     0m15.640s

real    0m8.858s
user    0m0.000s
sys     0m0.060s
pi@raspberrypi:~$ time dd if=~/test.tmp of=/dev/null bs=500K count=1024
1024+0 records in
1024+0 records out
524288000 bytes (524 MB) copied, 30.9214 s, 17.0 MB/s

real    0m30.941s
user    0m0.000s
sys     0m5.540s
pi@raspberrypi:~$

Need to add data for Vanilla RPi.

pietrushnic commented 9 years ago

Beacsue imporvements of sdhci-bcm2835 I drop support for bcm2835-mmc. Latest rpi-3.17.y contain fixes that maximize performance. DMA support will be added in future.