Ramon van Handel <[EMAIL PROTECTED]> wrote:
> I believe we shouldn't use the timer at all.
> Either we use direct access to framebuffer memory
> (DOSEMU full-screen driver or X DGA (needs special
> drivers in guest)) or we have the GUI clone() itself
> (or use pthreads ?) and have screen updating
> asynchronously in a separate thread.
Well, first of all the problem was not related to VGA
emulation, but to processing of X events, and maintaining
the keyboard queue. All these tasks are triggered from
the global timer signal.
To screen emulation specifically: whether we do it
asynchronously using signals or a thread is really
no difference as to performance on UP machines.
(The only difference is that by using sched_yield you tie
yourself to the host OSes scheduler quantum length, while
using a timer you can select the update frequency yourself.)
Using synchronous updates instead of async ones may be
even slower: there can be a *lot* of accesses to the video
memory, and causing a full VM switch for every byte written
might well be much slower than just reading the whole
thing say 50 times a second. (Getting just a 'modified'
bit from the monitor might be helpful, though.)
Bye,
Ulrich
