Wine(server) priority inversion on CK kernel mailing list

[Jeremy White]

> These could just be the usual known slow wineserver communication effects
> at work here, but I wanted to make sure you know about these issues on the
> CK list.

I suspect that the issue is much deeper than just the
wineserver effects; Windows scheduling requirements
are fundamentally different than the scheduling that the
Linux kernel tries to supply, and the differences
can be hard to troubleshoot.

Photoshop, for example, relies on the ability of a
thread to Sleep for precisely 5 ms, and then wake up in a certain
priority state.  The Linux kernel inverts that
(I forget the exact details, but we dug into this
in great detail this past fall), and so the Photoshop
thread has a great deal of difficulty.  AFAIR, we had
issues with the thread sleeping for 115 ms instead of
5 ms, and we alternately had problems with the thread starving
other threads in the system, so that nothing else was
being served.

On my todo list is an item to start a conversation with
the Kernel guys about these scheduling differences,
and to see if we can ask for a few tuning hooks to help
us better match Windows.  But I keep trying to goad
Alexandre into doing it, and he keeps reminding me that
I'm not supposed to bother him with anything until after
the Window Manager rewrite is done... <grin>.

But they seem receptive right now, so maybe I'll see
what I can do.

Cheers,

Jeremy