[PATCH 3/3] exa/mixed: Exclude frontbuffer from deferred pixmap handling.

[Maarten Maathuis]

2010/12/14 Michel Dänzer <michel at daenzer.net>:
> On Mon, 2010-12-13 at 19:42 +0100, Maarten Maathuis wrote:
>> - Apps like xterm can trigger a lot of fallback rendering.
>> - This can lead to (annoyingly) high latencies, because you
>>   have to wait for the block handler.
>> - You need a driver that doesn't directly access the front
>>   buffer to trigger this (NV50+ nouveau for example).
>> - Repeatingly doing dmesg on an xterm with a bitmap font
>>   will reveal that you never see part of the text.
>> - I have recieved at least one complaint in the past of slow
>>   terminal performance, which was related to core font
>>   rendering.
>> - This does sacrifice some throughput, not sure how much,
>
> Shouldn't be hard to measure.

I did a little test (catting a saved copy of dmesg) and the throughput
loss is about 25%.

>
>> but users tend to respond poorly to unexpected latency IMO.
>
> I'm sure some do, but I also suspect some do to unexpected slowness. :}
>
>
> --
> Earthling Michel Dänzer           |                http://www.vmware.com
> Libre software enthusiast         |          Debian, X and DRI developer
>



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