Re: [Qemu-devel] Storing code caching

["John R. Hogerhuis" <jhoger@pobox.com>]

On Thu, 2004-07-08 at 12:11, Julian Seward wrote:

> Nice idea, but ... I suspect it solves a non-problem really.  Caching
> translations is only worthwhile when translation time is a large
> part of overall run time, but I bet that's not the case.  It certainly
> isn't with Valgrind, which uses similar technology.
> 

Right. That's entirely possible, but just as much speculation without
any numbers.

No one knows until the work or analysis is done...

Translation time is certainly not negligible. And a better code
generator would quite likely swamp any improvements a persistent cache
could give. There's disk I/O to consider there too. But it is possible
the improvements would make a faster emulator.

It depends on requirements too I guess. If you don't care about load
time then you probably don't care about translation time either since
from the user's point of view they are going to be conflated.

> If you want to throw lots of hacking effort at QEMU to make it
> go faster, I suspect you'll need to be building a more sophisticated
> code generator, a la "lcc" (http://www.cs.princeton.edu/software/lcc).

Interesting... why do you bring up lcc specifically? Just browsing that
page and its FAQ didn't tell me much about it other than it is a
retargetable C compiler.