Re: [RFC] scheduler: improve SMP fairness in CFS

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



Tong Li wrote:
Without the global locking, the global synchronization here is simply ping-ponging a cache line once of while. This doesn't look expensive to me, but if it does after benchmarking, adjusting sysctl_base_round_slice can reduce the ping-pong frequency. There might also be a smart implementation that can alleviate this problem.

Scaling it proportionally to migration cost and log2(cpus) should suffice.

I don't understand why quantizing CPU time is a bad thing. Could you educate me on this?

It depends on how precisely you do it. We save a lot of power going tickless. If round expiration is re-introducing ticks on idle CPUs, we could waste a lot of power. Hardware is getting even more aggressive about power saving, to the point of allowing individual cores to be completely powered off when idle. We need to make sure the scheduler doesn't interfere with power management.

	-- Chris
-
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/

[Index of Archives]     [Kernel Newbies]     [Netfilter]     [Bugtraq]     [Photo]     [Stuff]     [Gimp]     [Yosemite News]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux RAID]     [Video 4 Linux]     [Linux for the blind]     [Linux Resources]
  Powered by Linux