Weird behaviour

[James Cameron]

On Sat, Feb 18, 2012 at 04:33:12PM -0500, Kevin Gordon wrote:
> On Tue, Feb 14, 2012 at 5:18 PM, James Cameron <quozl at laptop.org> wrote:
> > For your interest, next time you need it, there's an OpenFirmware
> > test feature for checking the fs-update transfer rates from USB.
> > ok null-fsdisk fs-update u:\fs.zd
> [...]
> I upgraded the firmware to Q3C01, which eliminated the
> write-block-start and finish not unique messages.
> 
> However invoking the  command null-fsdisk fs-update u:\os883.zd4
> (which is the build we use on these machines and is teh file on the
> USB drive) gives the following warnings on the good  (reference) XO
> 1.5:
> 
> Image size is larger than output device

Thanks.  Fixed in next release.  The null device had a zero size, and so
anything except a zero size input file triggered this abort.  The fix
[1] sets the null device to 32GB size.

In the meanwhile, should you still wish to test the performance of
fs-update without eMMC or microSD writes:

	ok dev /null : size 0 8 ; dend
	size isn't unique 
	ok null-fsdisk fs-update u:\os883.zd4

> file said highest block 29849 but wrote only as high as block 0
> file did not write a zero block, but wrote only as low as block 29489

These messages are a consequence of the abort, and therefore can be
ignored.  In the absence of this abort, the messages may be important.


The test using null-fsdisk only neuters the write to eMMC or microSD,
and the .zd file is still read and decompressed.

On an XO-1.75 using null-fsdisk, the fs-update reduced from 5:05 to
4:36, which shows that most of the time cost is the decompression.  The
same file read in without decompression [2] cost 1:26.

References:

1.  http://tracker.coreboot.org/trac/openfirmware/changeset/2870

2.  http://wiki.laptop.org/go/Forth_Lesson_23#read_a_large_file

-- 
James Cameron
http://quozl.linux.org.au/