From: Yves-Alexis Perez <corsac@debian.org>
To: Willy Tarreau <w@1wt.eu>,
linux-kernel@vger.kernel.org, stable@vger.kernel.org
Subject: Re: Feedback on 4.9 performance after PTI fixes
Date: Mon, 08 Jan 2018 18:21:37 +0100 [thread overview]
Message-ID: <1515432097.3305.66.camel@debian.org> (raw)
In-Reply-To: <1515431274.3305.59.camel@debian.org>
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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
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next prev parent reply other threads:[~2018-01-08 17:21 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-07 10:18 Feedback on 4.9 performance after PTI fixes Willy Tarreau
2018-01-08 17:07 ` Yves-Alexis Perez
2018-01-08 17:21 ` Yves-Alexis Perez [this message]
2018-01-08 18:26 ` Willy Tarreau
2018-01-08 20:26 ` Yves-Alexis Perez
2018-01-08 20:39 ` Willy Tarreau
2018-01-08 22:45 ` Pavlos Parissis
2018-01-08 17:26 ` David Laight
2018-01-09 7:09 ` Willy Tarreau
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