[Coco] DW4 problems

Sat Oct 13 06:54:03 EDT 2012

On Saturday 13 October 2012 06:36:19 Aaron Wolfe did opine:

> I replied directly to your bug report, but some general info in case
> other people see this message...
> 
> Generally if you see "OP_WRITE took X ms.  Server loaded or low on
> ram?" in the log, it's not actually anything to do with the server
> load or ram.
> I need to change that message.  If you happen to be running DW4 on an
> embedded linux system with a 133Mhz processor and 16MB ram, as I was
> testing when that message was put into the monitoring code, it is
> often accurate :)  However on a modern PC it usually means something
> quite different.
> 
> Every command/response exchange between the CoCo and the DW server is
> governed by a timeout of ~200ms.  Both the OS9 driver and the DW
> server will generally consider an operation to have failed if they
> wait that long for data from the other side.  Writing a sector is a
> particularly sensitive operation because the DW server doesn't want to
> say "OK, it worked" until it knows the sector has been committed to
> storage.  However, writing that sector to storage can take a while,
> especially if said storage is a remote FTP server or something like
> that.  For this reason DW times the write operations, and if writes
> take > a certain amount of time, DW switches to a caching strategy
> where sectors are first written to memory, the Coco is told "OK", and
> then a separate thread worries about actually getting them written to
> the source later.  In the event that DW is already using memory cache
> and a write *still* takes too long, it throws the "Server loaded or
> low on ram?" assuming incorrectly that the delay is it's own fault.
> 
> At the time I didn't think about the other way an operation can take
> too long, which is simply that the CoCo doesn't send an entire 256
> byte sector within the time limit.  However, this is the most likely
> case if you see that error on a modern PC.  For whatever reason, an
> operation was started and then the DW server didn't get enough bytes
> from the CoCo to complete it.
> 
> In Bob's case I suspect it's happening due to a clock operation that
> was added to the OS9 driver but the DW software (and I thought
> removed/fixed, but apparently not in the disk Bob has at least).  This
> caused the CoCo to send a clock timestamp every 60 seconds.  Because
> the server doesn't know about that operation, it ignores the opcode.
> However, the timestamp contains arbitrary values depending on the
> current time, and eventually it will contain a valid opcode in that
> data such as OP_WRITE.  As soon as this happens, the server expects
> sector data, but of course it doesn't get any, and we get the "server
> loaded" message.
> 
> tl;dr - If you see this message, it's probably due to garbage from the
> coco that happens to match the start of a valid operation
> 
> -Aaron
> 
> On Sat, Oct 13, 2012 at 3:53 AM, Bob Devries <devries.bob at gmail.com> 
wrote:
> > I seem to be getting a lot of time outs using DW4, which cause ERROR
> > 245 on the coco end. Here's some lines from the log:
> > 
> > Sat Oct 13 2012 17:36:09.250  WARN   DWProtocolHandler   dwproto-0-10 
> >       Timed out reading from CoCo in OP_WRITE Sat Oct 13 2012
> > 17:36:09.250  WARN   DWProtocolHandler   dwproto-0-10        OP_WRITE
> > took 235ms.  Server loaded or low on ram?
> > 
> > DW4 is being run on an Intel P4 2.8GHz with 2GB ram. Besides the usual
> > clutter running in a windows background (AVG etc) the only
> > application running is Outlook Express, set to grab emails every 10
> > mins.
> > 
> > The connection is like this:
> > 
> > Coco <--> ATEN USB dongle <--> 8-port powered USB hub <--> USB2 Port
> > on PC.
> > 
> > The CRC of DW is $5136C3
> > 

I will check the crc of my 'dw' module when dcheck gets done.  As 
drivewire.dsk downloads/installs go,and which I built that boot from, its 
likely a year old.

Is this the same as the modules/rbf/dw3.sb?
Here is an ident -m dw3
{t2|08}/DD/NITROS9/dw3install/6309L2/MODULES/RBF:ident -m dw3         

Header for:  dw3 
Module size: $0325    #805
Module CRC:  $166DC0 (Good) 
Hdr parity:  $29 
Edition:     $16      #22
Ty/La At/Rv: $21 $81 
Subr mod, 6809 obj, re-en, R/O 

So it is not the same one Bob has.  Does it do this potentially error 
causing time function?

> > Regards, Bob Devries
> > Dalby, QLD, Australia
> > 
> > PS: I sent a more extended bug report via the DW4 UI to wherever that
> > ends up.
> > 
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> > Coco at maltedmedia.com
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> 
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Cheers, Gene
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