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.kumar@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) tixy@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
-- IMPORTANT NOTICE: The contents of this email and any attachments are confidential and may also be privileged. If you are not the intended recipient, please notify the sender immediately and do not disclose the contents to any other person, use it for any purpose, or store or copy the information in any medium. Thank you.