On Wed, 2007-10-17 at 09:23 +0200, Ingo Molnar wrote: > * Ken Chen <[EMAIL PROTECTED]> wrote: > > > schedstat is useful in investigating CPU scheduler behavior. Ideally, > > I think it is beneficial to have it on all the time. However, the > > cost of turning it on in production system is quite high, largely due > > to number of events it collects and also due to its large memory > > footprint. > > > > Most of the fields probably don't need to be full 64-bit on 64-bit > > arch. Rolling over 4 billion events will most like take a long time > > and user space tool can be made to accommodate that. I'm proposing > > kernel to cut back most of variable width on 64-bit system. (note, > > the following patch doesn't affect 32-bit system). > > thanks, applied. > > note that current -git has a whole bunch of new schedstats fields in > /proc/<PID>/sched which can be used to track the exact balancing > behavior of tasks. It can be cleared via echoing 0 to the file - so > overflow is not an issue. Most of those new fields should probably be > unsigned int too. (they are u64 right now.) >
FWIW I can't see how this patch saves a _lot_ of space. The stats are per domain or per rq, neither are things that have a lot of instances. That said, I have no actual objection to the patch, just not getting it. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
