nanogui: make microwin api : client/server
Subject:
Re: make microwin api : client/server
From:
Jim Buzbee ####@####.####
Date:
25 Apr 2000 14:06:11 -0000
Message-Id: <3905A3F8.F3DB38E6@echostar.com>
Rob Taylor wrote:
...
> >
> well, depends what sort of shared memory usage tyou mean... some X servers
> support shared memoey usage in the sens that the client can buffer a whole
> load of X evemnts/requests in a shared memory area and only XSync/Xflush
> cause an actual pipe tansaction, which signals the Xserver to pull
> everything off the shared area and execute it.
> (note: I don't think XFree86 can do this, but i belive HP's can.)
>
> Anyway I think, although this is better than normal pipe transactions, I
> don't think it's the best option: you still need to marshal/unmarshal
> argumnets, which sucks. My suggestion is that the client actually does it's
> own drawing to the framebuffer, and the server processes simply deals with
> telling the client what screen regions it has use of (window
> management)(obviously with the relevent information stored in a shared
> memory buffer) and top-level event routing.
>
> What do people think?
>
The following is from the XFree86 mailing list where this subject was
discussed a bit. Read the quoted paper, but the final analysis seems to
indicate that on "modern hardware" doing the shared memory trick isn't
worth the effort. Of course many people using nano-gui won't be on
"modern hardware"...
Jim
------------
Rik Faith writes :
>
> I have completed an initial exploration of Shared Memory Transport and have
> written up a description of the implementation and the performance issues
> involved. Here is the abstract of the paper:
>
> Shared Memory Transport (SMT) is a mechanism for using shared memory
> to communicate X protocol information between the client application
> and the X server. This paper reviews existing SMT implementations,
> defines design criteria for SMT in XFree86, outlines a staged imple-
> mentation of SMT for XFree86, and analyzes the performance of this
> implementation. On workstations, SMT has historically provided a sig-
> nificant improvement in performance. However, on modern workstations
> and on modern PC-class hardware, SMT improves overall performance by
> less than 10%. On modern hardware, the performance of the host CPU
> (including the X server and operating system implementations) is well-
> matched to the performance of the graphics hardware. Because of this,
> the performance of the typical X operation is almost completely lim-
> ited by the performance of the graphics hardware, and the improvement
> in transport speed provided by SMT cannot provide large gains in ren-
> dering performance. Because of these observations, I do not recommend
> devoting more engineering time to the active improvement of the cur-
> rent SMT implementation for XFree86.
>
>
> The fully paper is available in several formats:
>
> http://precisioninsight.com/smt/smt.html
> http://precisioninsight.com/smt/smt.txt
> http://precisioninsight.com/smt/smt.ps
>
----------------------------------------------------------------------------------------------
