On Fri, Jun 8, 2012 at 9:58 AM, Anton Vorontsov anton.vorontsov@linaro.org wrote:
If you're saying that we should set up a timer in the userland and constantly read /proc/vmstat, then we will cause CPU wake up every 100ms, which is not acceptable. Well, we can try to introduce deferrable timers for the userspace. But then it would still add a lot more overhead for our task, as this solution adds other two context switches to read and parse /proc/vmstat. I guess this is not a show-stopper though, so we can discuss this.
Leonid, Pekka, what do you think about the idea?
That's exactly the kind of half-assed ABI that lead to people inventing out-of-tree lowmem notifiers in the first place.
I'd be more interested to know what people think of Minchan's that gets rid of vmstat sampling.