HZ value change groundings (Was: jitterless touchscreen input in .34) + FCSE question

Gennady Kupava gb at bsdmn.com
Mon Oct 25 12:16:44 CEST 2010

В Пнд, 25/10/2010 в 11:14 +0200, Patryk Benderz пишет:
> [cut]
> > Pros:
> > 1. Stay more in IDLE state. (less power consumption)
> > 2. If several tasks are active, do 2 times less context switches (and
> > our context switches are expensive). Do not think it will be 'slow'.
> > This is not applied to all tasks - but only to CPU bound ones.
> Hi Gennady,
> each time you come with such a news, it makes me wonder how much more
> can be done to make FR run faster? :)

Hi, Patryk

Hm... why not make short list of interesting non-trivial kernel
ideas? :)

Who knows, may be some fellow kernel dev who wish to learn something
about HW will find something interesting in list.

1. Performance: Investigate strange sd card speed (already tested that
this is not glamo<->cpu bus speed problem).
2. Performance: Investigate strange sdram r/w speed. Really not easy but
interesting task.
3. Performance: Implement usd card DMA
4. Performance: Our flash still do software ECC check while hw can do hw
ECC without problems.
5. Power consumption: In suspend, our dear PMU unit seem in Active
state. Investigate can we put it to Standby (this should save near 1mA
out of 5mA in Standby)

> [cut]
> > I did lmbenching and found that difference is few percent, but still
> > noticeable.
> Remember: small performance gain here, small there, and nex year it will
> be twice faster :)
> BTW, can you tell me if FCSE is already enabled in some recent kernel
> available for mere mortal users? If so, how can one check it?

Now it is not included in any kernel AFAIK.

Personally i am waiting for FCSE patch (as you can recall author
promised that he can do it then he'll have free time) for .34 kernel to
test it, do lmbenching and then attempt to convience Radek to include it
to QtMoko :)


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