2.4.x swim3 performance problem on PM4400 identified
boris at gajba.net
Sun Mar 30 18:28:04 EST 2003
On Sun, Mar 30, 2003 at 11:50:47AM +1000, Paul Mackerras wrote:
> Boris Bezlaj writes:
> > | kista:/tmp# dd if=swimmer of=/dev/fd0 bs=512 count=2880
> > | swim3: timeout reading sector 2647
> Hmmm, wonder why it's reading that sector?
> The timeout probably indicates that the sector header is corrupted or
> unreadable. The driver should probably retry after verifying that it
> is on the right track.
Well it is the _bad_ floppy case :)
> > | end_request: I/O error, dev 02:00 (floppy), sector 2647 <--bad sector
> > | dd: writing `/dev/fd0': Input/output error
> > | 2647+0 records in
> > | 2646+0 records out
> > | 1354752 bytes transferred in 134.614549 seconds (10064 bytes/sec)
> > after the error at sector 2647, swim3 seems to move the heads to sector 0
> > and write? another 2647 sectors. Any particular reason for that ?
> I don't think it's the swim3 driver itself that is doing that. I
> would start by stracing the dd to see what writes it is doing. It may
> be the block I/O layer doing something funny.
I will give it a shot later in the evening.
Many thanks for your effort 8)
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