Opportunity for speedup
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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