* Andi Kleen <[email protected]> wrote:
> [...] Even normal kernels must have reasonably good latency, as long
> as it doesnt cost unnecessary performance.
they do get reasonably good latency (within the hard constraints of the
possibilities of a given preemption model), due to the cross-effects
between the various preemption models, that i explained in detail in
earlier mails. Something that directly improves latencies on
CONFIG_PREEMPT improves the 'subsystem-use latencies' on PREEMPT_RT.
Also there's the positive interaction between scalability and latencies
as well.
but it's certainly not for free. Just like there's no zero-cost
virtualization, or there's no zero-cost nanokernel approach either,
there's no zero-cost single-kernel-image deterministic system either.
and the argument about binary kernels - that's a choice up to vendors
and users. Right now PREEMPT_NONE is dominant, so do you argue that
CONFIG_PREEMPT should be removed? It's certainly not zero-cost even on
the source code, witness all the preempt_disable()/preempt_enable() or
get_cpu()/put_cpu() uses.
Ingo
-
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]
