Re: [Xen-devel] [PATCH 0/3] xen: evtchn and gntdev device fixes and perf improvements

[David Vrabel <david.vrabel@xxxxxxxxxx>]

On 19/07/13 15:51, David Vrabel wrote:
> 
> Patch 3 improves the scalability of the evtchn device when it is used
> by multiple processes (e.g., multiple qemus).  As you can see from the
> graph[1] it is a signficant improvement but still less than ideal.  I
> suspect that this may be due to the per-domain event lock inside Xen
> rather than anything kernel-side.
> 
> The graphed data was collected from dom0 with 8 VCPUs on a host with 8
> CPUs.

Attached is the (slightly cheesy) test program I used to generate the
results.  This also triggered the deadlock fixed by patch 1.

It spawns N threads each of which opens /dev/xen/evtchn channel sets up
an event channel with both ends in the same domain.  The event channels
are manually distributed between the VCPUs.

David

Attachment: evtchn-stress.c
Description: Text Data

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