Re: [Xen-devel] [PATCH for-4.13 2/2] Rationalize max_grant_frames and max_maptrack_frames handling

["Durrant, Paul" <pdurrant@xxxxxxxxxx>]

> -----Original Message-----
> From: Xen-devel <xen-devel-bounces@xxxxxxxxxxxxxxxxxxxx> On Behalf Of Ian
> Jackson
> Sent: 26 November 2019 17:36
> To: George Dunlap <george.dunlap@xxxxxxxxxx>
> Cc: Juergen Gross <jgross@xxxxxxxx>; Stefano Stabellini
> <sstabellini@xxxxxxxxxx>; Julien Grall <julien@xxxxxxx>; Wei Liu
> <wl@xxxxxxx>; Paul Durrant <paul@xxxxxxx>; Andrew Cooper
> <Andrew.Cooper3@xxxxxxxxxx>; Konrad Rzeszutek Wilk
> <konrad.wilk@xxxxxxxxxx>; Marek Marczykowski-Górecki
> <marmarek@xxxxxxxxxxxxxxxxxxxxxx>; Hans van Kranenburg <hans@xxxxxxxxxxx>;
> Jan Beulich <jbeulich@xxxxxxxx>; xen-devel@xxxxxxxxxxxxxxxxxxxx
> Subject: Re: [Xen-devel] [PATCH for-4.13 2/2] Rationalize max_grant_frames
> and max_maptrack_frames handling
> 
> George Dunlap writes ("[PATCH for-4.13 2/2] Rationalize max_grant_frames
> and max_maptrack_frames handling"):
> > Xen used to have single, system-wide limits for the number of grant
> > frames and maptrack frames a guest was allowed to create.  Increasing
> > or decreasing this single limit on the Xen command-line would change
> > the limit for all guests on the system.
> 
> If I am not mistaken, this is an important change to have.
> 

It is, and many thanks to George for picking this up.

> I have seen reports of users who ran out of grant/maptrack frames
> because of updates to use multiring protocols etc.  The error messages
> are not very good and the recommended workaround has been to increase
> the default limit on the hypervisor command line.
> 
> It is important that we don't break that workaround!

Alas it has apparently been broken for several releases now :-(

  Paul

> 
> Thanks,
> Ian.
> 
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