Re: [PATCH] xen/netfront: Fix TX response spurious interrupts

[Elliott Mitchell <ehem+xen@xxxxxxx>]

On Thu, Jul 10, 2025 at 04:11:15PM +0000, Anthoine Bourgeois wrote:
> We found at Vates that there are lot of spurious interrupts when
> benchmarking the PV drivers of Xen. This issue appeared with a patch
> that addresses security issue XSA-391 (see Fixes below). On an iperf
> benchmark, spurious interrupts can represent up to 50% of the
> interrupts.

If this is the correct fix, near-identical fixes are needed for *all*
of the Xen front-ends.  Xen virtual block-devices and Xen PCI-passthrough
devices are also effected by a similar issue.

Thanks for finding a candidate fix, this effects many other people who
have been troubled by this performance issue.

FreeBSD will also need a similar fix.


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