Hi, Jesus Alberto Rodriguez Chavez wrote:
I have the same problem as you described. But II think you may be correct in that other parts
think that the problem is not based in the USB
stack but in the kernel itself.
of the kernel - e.g. disk cache, filesystem may
have some part to play in this. If it was just the
mass storage driver or USB layer then I would
not expect vfat filesystems to work significantly better under the same load.
I'm not sure if I've seen this behaviour or not. WhenHave you observed that when you mount a large USB partition the ammount of physical memory decreases, and the more that you use the FS, the less memory that you get until the system completely hangs, that is, without swapping, doesn\'t matter that I have 256 MB in RAM, once the physical memory is exhuasted, the system hangs.
I do a big write, say try and send 2Gb to the drive on
a machine with 256Mb then very quickly any spare RAM is used to buffer the write by the disk caching layer. Once it starts to write out to the device is when the problems start. It tends to happen gradually though,
initially a few 2-3 seconds lockups - getting more
frequent and longer until I'm locked out completely.
I suspect that if I waited a week or two it may
return but I have better thing to do :-).
It feels like something, somewhere, is choking up on
dealing with something other than writing out the
data and blocking everything else from running until
its done.
I will be trying a kernel patch to improve the handling of the systems memory, one called pre-emtive patch, but I only can do it on week ends, so we have to wait and see.
Interesting idea.
I got as far as trying a 2.4.20-pre10-ac2 kernel lastIn the while, does anybody have any good idea ?, may be i am following the wrong clue.
night to see if any of the differences in the ac series
help. Although I haven't tested it fully I was getting
much less of a problem with this kernel. I wrote a 2 Gb ext2 file system asynchronously to the drive.
For about the first Gb it maintained a rate of about
720-750 kb/s which is reasonable with only minor latency
problems. Over the last Gb though things got worse with
frequent latencies of 1-3 seconds and occassional freezes
of about 20-30 seconds. It kept going at a reasonable rate
though averaging about 700 kb/s for the entire write.
Looking at the working devices lists it appears the other
people are using certain USB HDDs without problems, however, it is not clear if they are using vfat rather than ext2. Is it possible some drives are not recognised fully
and are using the wrong transfer mode?
Please let me know if you turn up anything useful.
Regards,
Ian
--
Dr Ian David Flintoft Email: [EMAIL PROTECTED] Applied Electromagnetics Group Tel: +44 (0) 1904 432391
Department of Electronics Fax: +44 (0) 1904 433224 University of York Heslington YORK, UK YO10 5DD
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