Message-Id: <199701070948.LAA00149@castle.trendline.co.il>
Comments: Authenticated sender is <ronen@[192.114.11.13]>
From: "Ronen Friedman" <ronen AT Friendly DOT co DOT il>
To: Eli Zaretskii <eliz AT is DOT elta DOT co DOT il>
Date: Tue, 7 Jan 1997 11:37:03 +0000
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Subject: Re: DOS write buffers & DJGPP?
Reply-to: ronen AT Friendly DOT co DOT il
CC: djgpp AT delorie DOT com

Thanks, Eli

What I meant by the "controlling the behaviour" is what I said 
earlier - using off-times (once every few seconds) to perform the
actual writes.

I didn't know flush_disk_cache() interacts with the SmartDrv(), and 
assumed it is DOS that is affected. Perhaps the doc's should elaborate 
here?

But the main question remains: suppose I disable the SmartDrv. Can I 
force DOS to withhold writing onto the disk until an fsync()?

Thanks again
Ronen


> Date:          Mon, 6 Jan 1997 13:27:00 +0200 (IST)
> From:          Eli Zaretskii <eliz AT is DOT elta DOT co DOT il>
> Subject:       Re: DOS write buffers & DJGPP?
> 
> > We've concluded that some internal DOS buffer was filled, and DOS
> >  is dumping it onto our very slow FLASH disk. We tried using
> > _flush_disk_cache() on convenient times. This reduces the frequency
> > of the problem, but DOS still feels free to stop everything from time
> > to time to perform the I/O.
> 
> `_flush_disk_cache' is only appropriate if you load a disk cache such as 
> SmartDrv on your machine.  If not, use `sync' or `fsync'.
> 
> > Can I control this behaviour? should I do things differently?
> > Or is our explanation totally wrong?
> 
> You didn't explain how would you like to ``control this behavior''.  
> After all, the buffers must be flushed from time to time anyway, and the 
> writes to the flash memory *are* slow.  So what exactly would you like to 
> accomplish?
> 
> If you don't need all of the log file, but just its last X Mbytes, you 
> might install a RAM disk of a suitable size and make the log file 
> cyclically re-used.
> 
> 
--------------------------------
Ronen Friedman
Friendly Machines LTD
Phone: +972-9-8996750
FAX:   +972-9-8996751
ronen AT friendly DOT co DOT il