Re: [PATCH RFC 1/2] qspinlock: Introducing a 4-byte queue spinlockimplementation

[Raghavendra K T]

On 08/02/2013 02:39 AM, Waiman Long wrote:
> On 08/01/2013 04:23 PM, Raghavendra K T wrote:
> > On 08/01/2013 08:07 AM, Waiman Long wrote:
[..]
> > Though I could see some gains in overcommit, but it hurted undercommit
> > in some workloads :(.
>
> The gcc 4.4.7 compiler that I used in my test machine has the tendency
> of allocating stack space for variables instead of using registers when
> a loop is present. So I try to avoid having loop in the fast path. Also
> the count itself is rather arbitrary. For the first pass, I would like
> to make thing simple. We can always enhance it once it is accepted and
> merged.

Yes. agree.

> > I have not yet tested on bigger machine. I hope that bigger machine will
> > see significant undercommit improvements.
>
> Thank for running the test. I am a bit confused about the terminology.
> What exactly do undercommit and overcommit mean?

Undercommit means I meant total #vcpu < #pcpus in virtual env. so
overcommit should not be an issue in baremetal.

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/