Re: [RFC PATCH v8 1/9] Restartable sequences system call

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

 



On Fri, Aug 19, 2016 at 01:23:57PM -0700, Linus Torvalds wrote:
> On Fri, Aug 19, 2016 at 1:07 PM, Mathieu Desnoyers
> <mathieu.desnoyers@xxxxxxxxxxxx> wrote:
> >
> > Benchmarking various approaches for reading the current CPU number:
> 
> So I'd like to see the benchmarks of something that actually *does* something.
> 
> IOW, what's the bigger-picture "this is what it actually is useful
> for, and how it speeds things up".
> 
> Nobody gets a cpu number just to get a cpu number - it's not a useful
> thing to benchmark. What does getcpu() so much that we care?

The combination of CPU number and restartable sequence allows userspace
to write "per-CPU" rather than "per-thread" algorithms, just as the
kernel can.  The kernel can do that with preempt_disable().  Userspace
can do it with "tell me my CPU and restart me if preempted".

But yes, this needs a benchmark of, for instance, urcu implemented on
top of this, or some concrete data structure.
--
To unsubscribe from this list: send the line "unsubscribe linux-api" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html



[Index of Archives]     [Linux USB Devel]     [Video for Linux]     [Linux Audio Users]     [Yosemite News]     [Linux Kernel]     [Linux SCSI]

  Powered by Linux