[openbeos] Re: Question about Jobs(Command Line)

  • From: "Alexander G. M. Smith" <agmsmith@xxxxxxxxxx>
  • To: openbeos@xxxxxxxxxxxxx
  • Date: Thu, 12 Sep 2002 13:14:50 EDT (-0400)

> Andrew wrote:
> > One feature that would be really nice is if cat would use DMA.  
> > Currently the BFS driver uses DMA if you request a sufficiently large 
> block size. (>64KB?)
> > 
> > This size is settable in the kernel file, but I have no idea how to 
> > programmatically access the current setting.  If anyone knows that 
> information I would really like to know it for media kit purposes as 
> well.
> I don't think it's possible - although you could always load that 
> kernel settings file.

It's part of the file system info.  Recommended transfer size.  I think
the current 64K limit in BFS is too small, so I'm using 256K in my
file system (the file system defines it).  Various commands, like "cp"
use it to set their buffer size.

To get it, use fs_stat_dev() and look at the io_size field.

> Anyway, I think of having an additional open mode to have uncached file 
> access - it's already there for BSD, so we could just copy their flag 
> It's already part of fcntl.h in the repository, and maybe we will 
> implement it already in R1.

Yet another nice thing about OpenBeOS being open source; we can
implement whatever we want!  Now all we need is a good VM and file
system cache combination...

- Alex

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