Re: [PATCH v5 11/11] sched: introduce cgroup file stat_percpu

From: Andrew Morton
Date: Wed Jan 09 2013 - 16:16:56 EST


On Thu, 10 Jan 2013 01:10:02 +0400
Glauber Costa <glommer@xxxxxxxxxxxxx> wrote:

> The main advantage I see in this approach, is that there is way less
> data to be written using a header. Although your way works, it means we
> will write the strings "nice", "system", etc. #cpu times. Quite a waste.

Yes, overhead can be a significant issue with this type of interface.
But we already incurred a massive overhead by using a human-readable
ascii interface. If performance is an issue, perhaps the whole thing
should be grafted onto taskstats instead. Or create a new
taskstats-like thing.

btw, a more typical interface would be

cat /.../cpu0
nice:nn
system:nn
irq:nn

- the traditional one-per-line name:value tuples. But I'd assumed that
having a file per CPU would be aawkward.
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