Opportunity for speedup

Mitch Bradley wmb at laptop.org
Thu Feb 19 14:54:34 EST 2009

david at lang.hm wrote:
> if you have the diff of the images, do you need to read from the 
> framebuffer at all? since you know what you put there, and know what 
> you want to change, can't you just write your changed information to 
> the right place?

The framebuffer in this case is serving as persistent shared memory, 
thus avoiding the extra complexity of a client/server architecture to 
maintain the sequencing state.

The extremely-tiny (4K - 1 memory page) client program initially reads 
the first frame into the on-screen framebuf and the delta set into 
off-screen framebuffer memory.  On subsequent invocations, the client 
copies another delta into the on-screen framebuf.

If it is statically linked and uses only direct syscalls, the exec() 
overhead is minimal - no shell process instantiation, no script startup, 
no ld.so invocations, no mapping in shared libraries, no relocation.

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