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

[David Vrabel <david.vrabel@xxxxxxxxxx>]

This series includes a small collection of fixes improving the evtchn
and gntdev devices.

Patch 1 fixes a bug in the evtchn device that may cause deadlocks when
unbinding events or closing the device.  You may wish to consider it
for stable.

Patch 2 is a (very) minor performance improvement to
m2p_remove_override() when used by the the gntdev device.  The TLB
flush that it did not have any significant performance cost (since
it's a local CPU and single address only).

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.

David

[1] http://xenbits.xen.org/people/dvrabel/evtchn-device-scalability.png


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