Re: CVS commit: [tls-maxphys] src/sys/dev

[Thor Lancelot Simon <tls%panix.com@localhost>]

On Tue, Oct 09, 2012 at 05:21:17PM +0200, Manuel Bouyer wrote:
> On Tue, Oct 09, 2012 at 11:04:20AM -0400, Thor Lancelot Simon wrote:
> > Hmmmmm.
> > 
> > This will be an attempt to transfer an entire file -- 139264 will be the
> > entire file size of something, probably an executable it's paging in.
> > 
> > I saw this before -- I can't remember what caused it -- the "bad chunksize"
> > is, I think, because it's not power-of-2.  The cause will be in the UVM
> > readahead code.
> 
> It is. It looks like this code is different in tls-maxphys and HEAD.

Is it different in tls-maxphys-base and HEAD?  I played with this code
quite a bit while debugging previously, I believe.

> I wonder if we really want to read in power-of-2 chunks here, or just
> multiple of page size. Reading the code which calls ra_startio(),
> I'm not sure why size of chunksize would be a power-of-2.

I wondered that myself.  I think multiple of pagesize is probably okay,
but -- IIRC -- I couldn't convince myself we'd always do the right thing
with the residual.  Try it?

Thor