max xmit default to 0x4104 (16644). Why ...
rsharpe at richardsharpe.com
Mon Nov 3 16:25:55 GMT 2003
On Mon, 3 Nov 2003, Jeremy Allison wrote:
> On Sun, Nov 02, 2003 at 08:28:44PM -0800, Richard Sharpe wrote:
> > Hi,
> > In tracking down a benchmarking problem, I discovered the following:
> > /* Was 65535 (0xFFFF). 0x4101 matches W2K and causes major speed
> > improvements... */
> > /* Discovered by 2 days of pain by Don McCall @ HP :-). */
> > Globals.max_xmit = 0x4104;
> > This causes me major problems and I was wondering why the previous value
> > (of 65535) caused problems with Win2K.
> > I have not yet tested with Win2K and my testing has been confined to using
> > cifs_bm, but it also seems unlikely to be a problem on the surface. This
> > is the setting of the max amount data that Samba is capable of writing in
> > one go. If Windows does not like it, it is free to use a smaller size in
> > read(&X) requests if it likes to.
> This is one of those numbers that W2K uses that seems
> to cause their redirector to do different things if
> it's changed. I can't get to my HP mail right now
> but hopefully Don will chime up with the background.
OK, I will try to do more experimentation today. I tried with W2K SP4 last
night on a 100Mbps link, and it behaved correctly, AFAICS, with max xmit
set to 65535. However, I am willing to believe that MS have done something
silly with SP5 or 6.
Richard Sharpe, rsharpe[at]ns.aus.com, rsharpe[at]samba.org,
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