Re: [coldsync-hackers] Too heavy load. Breaking connections.

[Andrew Arensburger <arensb+CShackers@ooblick.com>]

On Wed, Nov 07, 2001 at 01:37:13PM +0100, Wojciech Godynski wrote:
> Justin C. Ferguson wrote:
> >When last we left our heros, they were speaking of:
> >>When I run dd to create huge file (1G) then start coldsync, it breaks 
> >>connection. I can't find what is the reason. I tried all debuging 
> >>facilities set to 10 logging to file, but it wouldn't explain me anything.
> >>System is heavy loaded. (128M RAM, left only 4M).
> >>How can I find out the reason?
> >>I think it shouldn't happen.
> >
> >	I'm willing to bet the high load throws off the timing of the serial
> >connection, but that's just a guess.

> Sorry. I don't understand what is the point.
> I think it shoudn't happen.
> I'd be glad if you could explain me what the problem is.

	Well, you're creating a large file; I don't know about Linux,
but UFS would need to stripe this file across several cylinder groups
on the disk, to say nothing of using multiple indirects in the inode.
You have the debugging turned all the way up on ColdSync, which means
it logs every byte it sends or receives, three times. You're also
running low on RAM, so presumably your machine is paging a lot
(possibly thrashing). If you have a typical desktop machine, then all
of this I/O is going to the same disk.
	In other mail, you said that the database you're syncing has
7000 records, which means you're generating lots of serial I/O. I'm
also pretty sure that the serial driver in Linux is flaky and drops
characters from time to time, which means that ColdSync has to try
resending the most recent packet or request, but it only has a certain
window of time in which to do this before the Palm times out.
	Under these circumstances, I wouldn't be surprised to hear
that the sync didn't complete. The only question is whether ColdSync
exits cleanly, or whether it dumps core.

	Try not creating a huge file while you're syncing, and turn
down the logging. That'll probably help.

-- 
Andrew Arensburger                      This message *does* represent the
arensb@ooblick.com                      views of ooblick.com
	We were unanimous -- in fact, everyone was unanimous.
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