Well, I didn't find any problem with USB boot. I'm just setting up u-boot to go
for a completely standard MMC boot and I'll continue to try to reproduce.
Tixy, could you try temporarily changing the default option to off for the
frequency-invariant load?
I think it'll be at line 3631 in your fair.c
hmp_data.freqinvar_load_scale_enabled = 1;
Change it to 0 to change the default.
Basically, there are two feature changes which are both disabled when you
disable CONFIG_HMP_VARIABLE_SCALE and I'd like to find out which is responsible.
The CONFIG_HMP_VARIABLE_SCALE control is responsible for a change which lets us
'stretch time' during load accumulation so that we can retain the optimised
math routines in Paul's patch but also control the rate of accumulation of load.
On top of that using the same sysfs code, is
CONFIG_HMP_FREQUENCY_INVARIANT_SCALE which uses a PM notifier to change a scale
factor so that the recorded loads are expressed in terms of the potential CPU
capacity rather than instantaneous capacity. This has the effect of stopping
HMP up migrations from happening when the frequency of the A7 cluster is still
low.
I can't think of any reason why either of these changes should result in
increased boot time other than some odd interaction between DVFS and IO wait
time which we haven't seen anywhere yet. Even then, it seems strange that we
could get such a slowdown. Presumably the IO itself wouldn't get slower, and
over the course of a whole boot the CPUs are not very busy anyway.
Regards,
Chris
> -----Original Message-----
> From: Viresh Kumar [mailto:viresh.ku...@linaro.org]
> Sent: 20 November 2012 10:13
> To: Chris Redpath; Jon Medhurst (Tixy)
> Cc: Andrey Konovalov; PDSW-power-team; Lists linaro-dev
> Subject: Re: [GIT PULL]; big LITTLE MP master v12
>
> On 20 November 2012 15:40, Jon Medhurst (Tixy) <t...@linaro.org> wrote:
> > I've redone my vexpress test integration branch [1] based on the new
> > big-LITTLE-MP-master-v12 and can confirm that an Android kernel
> builds
> > and boots on TC2 and A9 CoreTiles, both with and without the
> > big-LITTLE-MP.conf.
>
> Thanks.
>
> > What shall we do about the boot time and possibly other performance
> > regressions? I can disable CONFIG_HMP_VARIABLE_SCALE in vexpress
>
> I haven't done anything for this, as Chris reported he isn't facing
> this issue.
> @Chris?
>
> --
> viresh
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