On Wed, Jan 19, 2011 at 05:05:49PM +0900, Simon Horman wrote:
> On Wed, Jan 19, 2011 at 12:14:40PM +0900, Magnus Damm wrote:
> > Hi Simon,
> >
> > On Wed, Jan 19, 2011 at 9:09 AM, Simon Horman <horms@xxxxxxxxxxxx> wrote:
> > > Hi,
> > >
> > > I am currently interested in the read performance of the SDHI driver. ÂI
> > > ran the following tests on a Mackerel board using Linus's latest tree
> > > (6845a44a), which I believe has all of the outstanding patches from Arnd
> > > and Guennadi merged.
> >
> > Nice, thanks for testing this.
> >
> > > I have made the following crude performance measurements using
> > > several different cards.
> > >
> > > dd if=/dev/mmcblk1 of=/dev/null bs=512 count=100000
> > >
> > > SD1.1: Â Â Â Â Â7.0 MB/s
> > > SD2.0: Â Â Â Â Â7.0 MB/s
> > > SDHC Class 2: Â 7.1 MB/s
> > > SDHC Class 10: Â7.2 MB/s
> > >
> > > Whereas I would expect something like:
> > >
> > > SD1.1 card: Â Â 12 MB/s
> > > SD2.0 card: Â Â 24 MB/s
> > > SDHC Class 2: Â 24 MB/s
> > > SDHC Class 10: ÂFaster?
> >
> > Please have a look at the clock frequency set by the SDHI MFD driver
> > (hclk), together with the tmio-mmc settings in tmio_mmc_set_clock().
> > For the clock to be bumped up properly some capability/feature flags
> > may be needed:
> >
> > MMC_CAP_MMC_HIGHSPEED
> > MMC_CAP_SD_HIGHSPEED
> >
> > Not sure if they are set properly. Probably not.
>
> Actually this is one thing that I did check, sorry for not mentioning it.
> The clock does seem to be set correctly, to 50Mhz for the high-speed case,
> which iirc is everything except SD1.1.
>
> > > Possibly relevant portions of my .config are:
> > >
> > > CONFIG_MFD_SH_MOBILE_SDHI=y
> > > CONFIG_TMIO_MMC_DMA=y
> > > CONFIG_MMC_TMIO=y
> >
> > These two are also relevant:
> >
> > CONFIG_SH_DMAE=y
> > CONFIG_DMA_ENGINE=y
> >
> > DMA controller platform data is also needed, not sure the state of
> > your board. You can check out the counters in /proc/interrupts to see
> > if the DMA controller is active or not.
> {
> Thanks!
>
> I have CONFIG_DMA_ENGINE but not CONFIG_SH_DMAE.
I ran my tests again with CONFIG_SH_DMAE (and CONFIG_DMA_ENGINE)
enabled and the results are substantially better. Although
the results are still below the theoretical speeds of the cards.
Read Speed - SHDI
SD1.1: 9.9 MB/s
SD2.0: 17.2 MB/s
SDHC Class 2: 17.0 MB/s
SDHC Class 10: 17.2 MB/s
MMC4.0: 8.6 MB/s <-- Clocked down to 12Mhz due to driver limitations
I also tested the Write Speed
SD1.1: 2.4 MB/s <-- Faster than expected
SD2.0: 2.8 MB/s <-- Faster than expected
SDHC Class 2: 2.5 MB/s <-- Faster than expected
SDHC Class 10: 3.8 MB/s <-- Slower than expected
MMC4.0: 2.1 MB/s <-- Clocked down to 12Mhz due to driver limitations
For reference I obtained the following results on my laptop,
which according to dmesg has a SAMSUNG MMCRE28G VBM1 PQ.
Read
SD1.1: 10.0 MB/s
SD2.0: 19.2 MB/s
SDHC Class 2: 19.4 MB/s
SDHC Class10: 17.9 MB/s <---- What!!!?
MMC4.0: 8.2 MB/s
Write
SD1.1: 2.7 MB/s
SD2.0: 3.4 MB/s
SDHC Class 2: 3.1 MB/s
SDHC Class10: 3.8 MB/s <---- What!!!?
MMC4.0: 2.0 MB/s
--
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
