Opportunity for speedup
wmb at laptop.org
Thu Feb 19 16:49:50 EST 2009
david at lang.hm wrote:
> d) compile the delta set into the client program.
That works, but
1) It requires more work from the VM system on each invocation of the
client program, which is now 1.x MB instead of 4K.
2) If a deployment wants to change the image set, it needs a compiler
toolchain instead of a (small) delta-encoding program.
Speed-wise, (d) might be a wash, or perhaps even a slight win. It
depends on how efficient the VM system is, and the effectiveness of the
filesystem buffer cache at preventing re-reads of the client process
image (paging directly from JFFS2 is not possible).
The framebuffer hack avoids numerous assumptions about the effectiveness
of clever but complex subsystems (e.g. the VM system, the filesystem
buffer cache, the shared library mechanisms, zlib, JFFS2 compression, ...).
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