Hello, MMC driver for JZ4740 SoC is currently relying on PIO mode only for data transfers. The patch that comes as a follow-up of this message allows the use of DMA for data transfers. According to the following DMA vs PIO benchmarks there seems to be a slight improvement in transfer speed with the Ben NanoNote booting from SD card, while load average seems to be roughly on par: * With DMA: Test cases | root@BenNanoNote:/# uptime | root@BenNanoNote:/# time zcat root/fedora-16.iso.gz > /dev/null && uptime -----------|---------------------------------------------------------------------------------------------------------------------------------- Test run 1 | 00:20:55 up 1 min, load average: 1.26, 0.42, 0.14 | 00:26:10 up 6 min, load average: 2.89, 1.94, 0.89 Test run 2 | 00:30:22 up 1 min, load average: 1.16, 0.38, 0.13 | 00:35:34 up 6 min, load average: 2.68, 1.86, 0.85 Test run 3 | 00:39:56 up 1 min, load average: 1.16, 0.38, 0.13 | 00:45:06 up 6 min, load average: 2.57, 1.76, 0.81 -----------|---------------------------------------------------------------------------------------------------------------------------------- Average | 1 min, load average: 1.19, 0.39, 0.13 | 6 min, load average: 2.71, 1.85, 0.85 * With PIO: Test cases | root@BenNanoNote:/# uptime | root@BenNanoNote:/# time zcat root/fedora-16.iso.gz > /dev/null && uptime ---------------------------------------------------------------------------------------------------------------------------------------------- Test run 1 | 00:50:47 up 1 min, load average: 1.42, 0.49, 0.17 | 00:56:52 up 7 min, load average: 2.47, 2.00, 0.98 Test run 2 | 01:00:19 up 1 min, load average: 1.21, 0.39, 0.14 | 01:06:29 up 7 min, load average: 2.45, 1.96, 0.96 Test run 3 | 01:11:27 up 1 min, load average: 1.15, 0.36, 0.12 | 01:17:33 up 7 min, load average: 2.63, 2.01, 0.97 -----------|---------------------------------------------------------------------------------------------------------------------------------- Average | 1 min, load average: 1.26, 0.41, 0.14 | 7 min, load average: 2.52, 1.99, 0.97 DMA tranfers performance might be further improved with a latter patch by taking advantage of the asynchronous request capability of the MMC framework. Changes were rebased on top of linux master branch, built and tested successfully. The following changes since commit 4c83445: Linux 3.16-rc3 are available in the git repository at: git://git.seketeli.net/~apelete/linux.git mmc-dma-jz4740 -- 1.7.10.4 -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
