Input latency

[Daniel van Vugt]

I observed egltriangle on the N10 (2 cores):
server 30%
client 20%

I misinterpreted that as 100% of one core, which is true for some tools, 
and "top" on some Unixes. But I just realized top on Linux goes to 100% 
multiple times (for each core).

So my assessment should have been 50% of one core, sorry.


On 17/12/13 07:30, Kevin Gunn wrote:
> hey Daniel - thanks for the numbers, however the last statement of
> having a core 100% loaded with mir_demo_client_egltriangle doesn't seem
> reasonable.
> running on N4 shows ~20% load on cpu at most.
>
> br,kg
>
>
> On Mon, Dec 16, 2013 at 2:40 AM, Daniel van Vugt
> <daniel.van.vugt at canonical.com <mailto:daniel.van.vugt at canonical.com>>
> wrote:
>
>     Nexus10 (3.4.0-4-manta)
>     Direct 1.0ms with sporadic spikes to 74ms, sometimes 400ms
>     Nested 1.2ms with sporadic spikes to 100ms, sometimes 1000ms
>
>     I'm not convinced the problem is specifically Android. It could just
>     be a common issue visible on the slowest hardware.
>
>     On the Nexus10, just running a single server and client
>     (egltriangle) occupies almost 100% of one of the cores. So stressing
>     the CPU doesn't leave much time for being responsive.
>
>
>
>     On 13/12/13 17:31, Daniel van Vugt wrote:
>
>         Here are some fun numbers I've collected about the latency
>         between input
>         events sent from the top-level Mir server to a client. All in
>         milliseconds...
>
>         Desktop (3.12.0-7-generic)
>         Direct 0.8ms
>         Nested 1.3ms
>
>         Desktop (3.11.0-11-lowlatency)
>         Direct 1.0ms
>         Nested 1.7ms
>
>         Nexus4 (3.4.0-3-mako)
>         Direct 0.9ms
>         Nested 1.5ms with high variance; frequent spikes to 73ms.
>         Sometimes 700ms.
>
>         The above numbers are for motion events. Key events appear to be
>         twice
>         as fast (half the latency). This suggests we could yet optimize the
>         processing of motion events to perform better like key events do.
>
>         In summary, we're looking pretty good. Only the Nexus has potential
>         usability issues, and even then, only with nested servers.
>
>         - Daniel
>
>
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