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 18:07:54 +0100 [thread overview]
Message-ID: <1515431274.3305.59.camel@debian.org> (raw)
In-Reply-To: <20180107101856.GA9590@1wt.eu>
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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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next prev parent reply other threads:[~2018-01-08 17:07 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 [this message]
2018-01-08 17:21 ` Yves-Alexis Perez
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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