On Thursday 07 June 2012, David Brown wrote:
> On Wed, Jun 06, 2012 at 07:11:37AM +0000, Arnd Bergmann wrote:
>
> > If you don't need the data on your card, could you run these
> > commands on yours:
> >
> > for i in 2 3 30 31 ; do
> > sudo flashbench --open-au --open-au-nr=30 --erasesize=$[512 * 1024] \
> > /dev/mmcblk0 --offset=$[24*1024*1024]
> > done
>
> Did you mean to use $i somewhere in that loop?
oops, yes it should be "--open-au-nr=$i"
> I ran it with the
> command given above (just once since it doesn't mention $i). Also,
> this is on a USB card reader. I'd have to get a bit more creative to
> be able to run this on my target, since the card is also the root
> filesystem.
USB card reader is fine for this test.
> 512KiB 962K/s
> 256KiB 398K/s
> 128KiB 201K/s
> 64KiB 101K/s
> 32KiB 152K/s
> 16KiB 719K/s
FWIW, these are the results for the "good" card:
for i in 2 3 30 31 ; do echo == $i == ; sudo ./flashbench --open-au
--open-au-nr=$i --erasesize=$[512 * 1024] /dev/mmcblk0
--offset=$[24*1024*1024] ; done
== 2 ==
512KiB 7.42M/s
256KiB 7.65M/s
128KiB 7.64M/s
64KiB 7.41M/s
32KiB 6.46M/s
16KiB 4.78M/s
== 3 ==
512KiB 7.9M/s
256KiB 8.06M/s
128KiB 8.2M/s
64KiB 8.35M/s
32KiB 6.61M/s
16KiB 3.95M/s
== 30 ==
512KiB 8.41M/s
256KiB 8.21M/s
128KiB 8.16M/s
64KiB 8.32M/s
32KiB 6.76M/s
16KiB 4.31M/s
== 31 ==
512KiB 8.08M/s
256KiB 7.41M/s
128KiB 6.73M/s
64KiB 5.73M/s
32KiB 3.87M/s
16KiB 1.78M/s
note how for values up to open-au-nr=30 the performance is stable for all block
sizes over 64k and only degrades a little below that, while for open-au-nr=31
it gets much slower for small block sizes.
The "bad" card looks very similar to yours:
for i in 2 3 30 31 ; do echo == $i == ; sudo ./flashbench --open-au
--open-au-nr=$i --erasesize=$[512 * 1024] /dev/mmcblk0
--offset=$[24*1024*1024] ; done
== 2 ==
512KiB 382K/s
256KiB 232K/s
128KiB 272K/s
64KiB 535K/s
32KiB 521K/s
16KiB 1.21M/s
== 3 ==
512KiB 393K/s
256KiB 176K/s
128KiB 223K/s
64KiB 606K/s
32KiB 585K/s
16KiB 976K/s
== 30 ==
512KiB 752K/s
256KiB 359K/s
128KiB 191K/s
64KiB 103K/s
32KiB 145K/s
16KiB 827K/s
== 31 ==
^C
(I skipped this one, it's rather pointless)
The effect becomes much more visible by trying erasesize=4MB:
for i in 2 3 4 ; do echo == $i == ; sudo ./flashbench --open-au --open-au-nr=$i
--erasesize=$[4096 * 1024] /dev/mmcblk0 --offset=$[24*1024*1024] ; done
== 2 ==
4MiB 3.09M/s
2MiB 4.93M/s
1MiB 5.52M/s
512KiB 5.52M/s
256KiB 5.53M/s
128KiB 5.51M/s
64KiB 5.52M/s
32KiB 4.51M/s
16KiB 1.87M/s
== 3 ==
4MiB 4.34M/s
2MiB 3.61M/s
1MiB 1.67M/s
512KiB 1.48M/s
256KiB 1.39M/s
128KiB 1.21M/s
64KiB 1.14M/s
32KiB 1.03M/s
16KiB 2.08M/s
== 4 ==
4MiB 5.52M/s
2MiB 3.45M/s
1MiB 1.65M/s
512KiB 826K/s
256KiB 414K/s
128KiB 208K/s
64KiB 104K/s
32KiB 247K/s
16KiB 2.24M/s
So this card can handle 2 open AUs just fine, three of them barely,
but not 4 or more, which is not a particular good behavior. For any
block sizes of 16kb or smaller, this card does provide some form of
caching though that makes up for this problem to some degree.
Arnd
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