linux-kernel - Re: Feedback on 4.9 performance after PTI fixes

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Mon, 08 Jan 2018 18:21:37 +0100
From:   Yves-Alexis Perez <corsac@...ian.org>
To:     Willy Tarreau <w@....eu>, linux-kernel@...r.kernel.org,
        stable@...r.kernel.org
Subject: Re: Feedback on 4.9 performance after PTI fixes

On Mon, 2018-01-08 at 18:07 +0100, Yves-Alexis Perez wrote:
> 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.

More details on this: https://groups.google.com/forum/m/#!topic/mechanical-sympathy/L9mHTbeQLNU

Regards,
-- 
Yves-Alexis
Download attachment "signature.asc" of type "application/pgp-signature" (489 bytes)