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Re: [PATCH v3] xen: speed up grant-table reclaim



On 27.06.23 19:22, Demi Marie Obenour wrote:
When a grant entry is still in use by the remote domain, Linux must put
it on a deferred list.  Normally, this list is very short, because
the PV network and block protocols expect the backend to unmap the grant
first.  However, Qubes OS's GUI protocol is subject to the constraints
of the X Window System, and as such winds up with the frontend unmapping
the window first.  As a result, the list can grow very large, resulting
in a massive memory leak and eventual VM freeze.

To partially solve this problem, make the number of entries that the VM
will attempt to free at each iteration tunable.  The default is still
10, but it can be overridden at compile-time (via Kconfig), boot-time
(via a kernel command-line option), or runtime (via sysfs).

You are still mentioning Kconfig.

For the sysfs entry you should add something under Documentation/ABI. Sorry
I didn't spot this omission previously.


Juergen

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