On 03/05/2011 05:35 PM, Marcelo Tosatti wrote:
TCG and KVM execution behaviour can become more
similar wrt locking by dropping qemu_global_mutex during generation and
execution of TBs.
Of course for memory or PIO accesses from vcpu context qemu_global_mutex
must be acquired.
-icount already has most of the machinery needed for this.
At this point, I think people interested in TCG should choose between
staying with legacy and gaining a bit more speed for uniprocessor
simulation, or following KVM with a more complex architecture and
finer-grained locking---but also a more future-proof design.
BTW, I'll post soon patches for iothread -icount that work (at least in
my tests), are much simpler than anything I posted so far, and hopefully
will show that iothread is not fundamentally incompatible with anything
(and in fact can simplify things much more than complicate them).
With that in place, it becomes easier to justify further improvements
regarding parallelization, such as using a read-write lock for
l1_phys_map / phys_page_find_alloc.
Or URCU (userspace RCU), too.
Paolo
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