Nested servers frame rate

[Thomas Voß]

On Wed, Dec 18, 2013 at 9:43 AM, Daniel van Vugt
<daniel.van.vugt at canonical.com> wrote:
> At first glance, comparing frame rates between direct (single) and nested
> (double) server configurations reveals nothing unexpected...
>
> Full screen
> Direct (bypass) 2600
> Direct (bypass off) 2400
> Nested (bypass) 2450
> Nested (bypass off) 2330
>
> But for surfaces which can't be bypassed, something strange happens; nesting
> is faster!
>
> Windowed
> Nested 4890
> Direct 4400
>
> My best theory right now is that we're crippling Mir in the single server
> case due to:
> https://bugs.launchpad.net/mir/+bug/1253868
> and nesting provides a workaround for that problem by supplying extra levels
> of buffering.

Not sure I'm following your reasoning here: The bug states exactly the
opposite, i.e., additional buffering wouldn't help.
In addition: I do not see how a steady-state update scheme on the
client-side is a problem here. If there are more than two buffers
available per surface, the client almost immediately receives a new
buffer when it calls next_buffer. Sure, there is always only one
buffer in flight, but I cannot see why this would lead to the numbers
you are reporting here.

Cheers,

  Thomas

>
> Can anyone else think why nested would sometimes be faster than not nested?
>
> - Daniel
>
> --
> Mir-devel mailing list
> Mir-devel at lists.ubuntu.com
> Modify settings or unsubscribe at:
> https://lists.ubuntu.com/mailman/listinfo/mir-devel