[Bug 56851] conhost runs at 20fps

[WineHQ Bugzilla]

https://bugs.winehq.org/show_bug.cgi?id=56851

Eric Pouech  changed:

What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|wineconsole runs at 20fps   |conhost runs at 20fps
    Regression SHA1|8ccf24ccb0a4362c407aea61927 |
                   |e604e60d41f6e               |
                 CC|                            |[e-mail]

--- Comment #2 from Eric Pouech  ---
1) changed title as the relevant component is conhost (wineconsole just ensures
that program is run in conhost in window mode)

Made quick timing comparisons between native & wine. This requires to measure
the same things:
- ensure that window size & screen buffer size are equal between native and
wine. Measurements made with screen buffer 120x9000 and window 120x30.
- ensure that initial state of screen buffer is the same (adding cls on top of
.bat)
- adapt script to run and time execution over a given number of iterations
(measurements done with 2000 and 20000 iterations)

native & wine on same HW, windows running under a VM

native exec time:
- relatively stable between 2.6 & 2.8s (2000 iterations)
- 27 to 28s (for 20000 iterations)

Wine exec time (current tip)
- greater dispersion: 2.7 up to 3.7s (2000 iterations), average at 3.4s
- 28 to 30s (20000 iterations)

Reversing patch tagged at culprit:
- 2000 iterations on 155s!!

I think that's enough to remove the tagged SHA1 as a regression.

The reasons of commit 8ccf24ccb0a4362c407aea61927e604e60d41f6e is not to have
an update for every single change, but to pack several changes into a single
update.

Increasing the delay in update_window_config() will give slightly better
execution time as it's going to reduce the number of window refreshes. But at
the cost of having to wait longer for echo when you're typing. So I wouldn't
favor that.

These figures should be confirmed by larger testing (and esp. on bare metal for
windows), but as of today, considering with the 20000 iterations figures above
(that somehow lower impact of startup time), I don't see a great discrepancy
between Wine and native.