Juergen Gross
2008-Dec-17 12:25 UTC
[Xen-devel] [Patch 1 of 2]: PV-domain SMP performance XEN-part
-- Juergen Gross Principal Developer IP SW OS6 Telephone: +49 (0) 89 636 47950 Fujitsu Siemens Computers e-mail: juergen.gross@fujitsu-siemens.com Otto-Hahn-Ring 6 Internet: www.fujitsu-siemens.com D-81739 Muenchen Company details: www.fujitsu-siemens.com/imprint.html _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
Juergen Gross
2008-Dec-22 06:10 UTC
Re: [Xen-devel] [Patch 1 of 2]: PV-domain SMP performance XEN-part
George Dunlap wrote:> The idea might be interesting, but this implementation needs some > work. Xen shouldn''t be reading a guest-writable bit of memory to > determine if it''s already delayed the guest; it needs to store that > information somewhere else. As it is, a rogue guest could extend its > time indefinitely by just writing 0 there every couple hundred > instructions.Thanks for finding this one! The correction is quite simple, I can just use sd->delay_desched for this purpose instead.> > It should probably be something taken care of in the individual > schedulers, rather than in the abstract scheduling code. > > At any rate, let''s see if there''s a significant performance difference > between this and yield-after-spinning-awhile, and then we can work on > the architecture.Agreed. Juergen -- Juergen Gross Principal Developer IP SW OS6 Telephone: +49 (0) 89 636 47950 Fujitsu Siemens Computers e-mail: juergen.gross@fujitsu-siemens.com Otto-Hahn-Ring 6 Internet: www.fujitsu-siemens.com D-81739 Muenchen Company details: www.fujitsu-siemens.com/imprint.html _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel