Re: Feedback on 4.9 performance after PTI fixes

[Yves-Alexis Perez]

On Sun, 2018-01-07 at 11:18 +0100, Willy Tarreau wrote:
>   - the highest performance impact on VMs comes from having PTI on the
>     guest kernel (-45%). At this point it makes no difference whether
>     the host kernel has it or not.

Hi Willy,

out of curiosity, is the pcid/invpcid flags exposed to and used by your guest
CPU? It might very well that the PCID optimisations are not used by the guests
here, and it might be worth either checking on bare metal or with the PCID
optimisations enabled.

Regards,
-- 
Yves-Alexis

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