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RE: DDraw Blt vs BltFast


Ralf,

Those are some very interesting results.  I especially like the ones where
Cygwin is 10 to 1000 times slower than Linux :)  Oh well... I can't bitch
anymore for fear of obligating myself to contribute to Cygwin proper.

Harold

> -----Original Message-----
> From: cygwin-xfree-owner@cygwin.com
> [mailto:cygwin-xfree-owner@cygwin.com]On Behalf Of Ralf Habacker
> Sent: Tuesday, March 12, 2002 3:30 AM
> To: Cygwin-Xfree
> Subject: RE: DDraw Blt vs BltFast
>
>
> >
> > On Mon, 11 Mar 2002, Harold Hunt wrote:
> >
> > > Alexander,
> > >
> > > Because the following article:
> > >
> > >
> > http://msdn.microsoft.com/library/default.asp?url=
> > /library/en-us/wcegmm/htm/
> > > ddover_51.asp
> > >
> > > states that:
> > >
> > > "BltFast cannot be used on surfaces that have
> > an attached clipper."
> >
> > Ok.
> >
> > > We use a clipper to account for any other
> > Windows window overlaying our
> > > window, which would cause a portion of our blit
> > destiation to be
> > > undrawable... which would mean that we wouldn't
> > be allowed to use BltFast.
> > >
> > > Now... could we use BltFast in DirectDraw
> > fullscreen modes?
> >
> > Not needed. The blitting does not slow down the
> > server significantly. I
> > think the cygwin socket layer slow much more.
>
> Do you have seen the lmbench results on the cygwin list
> http://sources.redhat.com/ml/cygwin/2002-01/msg01719.html
> This confirm your statement.
>
> *Local* Communication bandwidths in MB/s - bigger is better
> -----------------------------------------------------------
> Host                OS  Pipe AF    TCP  File   Mmap  Bcopy
> Bcopy  Mem   Mem
>                              UNIX      reread reread (libc)
> (hand) read write
> --------- ------------- ---- ---- ---- ------ ------ ------
> ------ ---- -----
> BRAMSCHE  CYGWIN_NT-5.0 93.9 17.6 40.7  335.0  477.7  145.0
> 134.0 477. 195.9
> BRAMSCHE   Linux 2.2.18 343. 235. 64.4  177.7  238.5   71.5
> 61.4 238.  75.3
>
> I have done some analysing work with this and with the
> cygwin daemon (cygserver transport classes) there may be a
> way in the future to implement unix domain sockets with
> named pipes which speed up unix domain sockets up to 250
> MB/s, as I have measured with a quick an dirty sample
> implementation. (Unfortunally currently I have no time to
> work on)
>
> Another way seems to me in using local connection for the
> xtrans layer, but there are two ioctl functions missing in
> cygwin I_FDINSERT and I_RECVFD.
>
> I_FDINSERT
> Creates a message from specified buffer(s), adds information
> about another STREAM, and sends the message downstream.
>
> I_RECVFD
> Retrieves the reference to an open file description from a
> message written to a STREAMS-based pipe using the I_SENDFD
> command, and allocates a new file descriptor in the calling
> process that refers to this open file description.
>
> In any case there is some work to do.
>
> Regards
> Ralf
>
>


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