Re: [Xen-devel] [PATCH v2 1/6] xen/tools: credit2: soft-affinity awareness in runq_tickle()

[George Dunlap <george.dunlap@xxxxxxxxxx>]

On 07/27/2017 01:05 PM, Dario Faggioli wrote:
> Soft-affinity support is usually implemented by means
> of a two step "balancing loop", where:
> - during the first step, we consider soft-affinity
>   (if the vcpu has one);
> - during the second (if we get to it), we consider
>   hard-affinity.
> 
> In runq_tickle(), we need to do that for checking
> whether we can execute the waking vCPU on an pCPU
> that is idle. In fact, we want to be sure that, if
> there is an idle pCPU in the vCPU's soft affinity,
> we'll use it.
> 
> If there are no such idle pCPUs, though, and we
> have to check non-idle ones, we can avoid the loop
> and to both hard and soft-affinity in one pass.
> 
> In fact, we can we scan runqueue and compute a
> "score" for each vCPU which is running on each pCPU.
> The idea is, since we may have to preempt someone:
> - try to make sure that the waking vCPU will run
>   inside its soft-affinity,
> - try to preempt someone that is running outside
>   of its own soft-affinity.
> 
> The value of the score is added to a trace record,
> so xenalyze's code and tools/xentrace/formats are
> updated accordingly.
> 
> Suggested-by: George Dunlap <george.dunlap@xxxxxxxxxx>
> Signed-off-by: Dario Faggioli <dario.faggioli@xxxxxxxxxx>
> Reviewed-by: George Dunlap <george.dunlap@xxxxxxxxxx>

The primary focus of this patch is credit2, so the title should probably
be xen/credit2, right?

I can change that on checkin.

 -George

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