[PATCH 2/2] gta02-drm-defconfig: enable FCSE and PREEMPT

Martix martix.cz at gmail.com
Thu Sep 2 01:09:46 CEST 2010


I have problem with missing option for ar when running lmbench on SHR.
I can try it with Qt Moko, but I'm leaving for two weeks and I don't
know whether I'll have enough time to do it before I return.

Yes, X11 performance is mostly about Glamo, but X11 is also protocol
which consumes CPU and can be affected by overall system latency, when
running multiple applications. I am looking around at benchmark, which
could compare real application use cases.

My only case is low latency mobile phone/PDA.

May I ask what is your reason for keeping PREEMPT disabled? I thought
the reason was too expensive (time consuming) context switching.
PREEMPT causes more frequent context switches, which was expensive
without FCSE, but situation has changed. Now with FCSE we need less
time for context switch and we don't need flush cache at every context
switch. So, we can use low latency advantages.

I would like to see also benchmark numbers instead of feeling or user
experience. I found interbench. [1] I'll use it to provide some basic
result, but it would be nice to have proper EFL/FSO/D-Bus benchmark
for testing and comparing our Neo FreeRunner use cases on multiple SW

[1] http://users.on.net/~ckolivas/interbench/



2010/9/1 Gennady Kupava <gb at bsdmn.com>:
> Hm, hi.
> I really not sure how to test it in a best way. I am really ok with any
> method which can show clear benefit.
> Also, i think if lmbench is hard to run in shr (strange, i think Jama
> told shr has gcc and make, what is else need?), why not do testing in
> some other distro. for example qtmoko is ready debian image, so you can
> just run tests. anyway you need to disable all shr services before
> running test.
> x11 bechmark will show you glamo speed. efl? hm... may be some dbus
> benchmark... i have no other idea.
> my position, is that PREEMPT should be enabled only if it is really
> needed. So, i am trying to understand in which particular case (one for
> the beginning!) it is really need.
> if you don't know i am the person who insisted on disabling PREEMPT, but
> consider me open. i'd be like to change my opinion, but so far i saw no
> arguments expect something like 'it is cool'.
> Gennady
> В Срд, 01/09/2010 в 19:38 +0200, Martix пишет:
>> Could you suggest application benchmarks which should I try, maybe
>> some EFL or X11 based benchmark? lmbench is broken on SHR.
>> Regards,
>> Martix
>> 2010/9/1 Gennady Kupava <gb at bsdmn.com>:
>> >> You meant hardware event? I am talking about common multitasking
>> >> response times, when using more applications on FR.
>> >
>> > What is meaming of 'common multitasking response time'?
>> > I have 100Mhz kernel here, and i can't notice any slowdowns.
>> >
>> > Response to what? Can you describe or provide example?
>> >
>> > Have you tried kernel with and without preempt? Can you feel any
>> > difference? Did you done some testing?
>> >
>> > Gennady
>> >
>> >

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