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

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Message-ID: <20180108203920.GB11238@1wt.eu>
Date:   Mon, 8 Jan 2018 21:39:20 +0100
From:   Willy Tarreau <w@....eu>
To:     Yves-Alexis Perez <corsac@...ian.org>
Cc:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Subject: Re: Feedback on 4.9 performance after PTI fixes

On Mon, Jan 08, 2018 at 09:26:10PM +0100, Yves-Alexis Perez wrote:
> On Mon, 2018-01-08 at 19:26 +0100, Willy Tarreau wrote:
> > You're totally right, I discovered during my later developments that
> > indeed PCID is not exposed there. So we take the hit of a full TLB
> > flush twice per syscall.
> 
> So I really think it might make sense to redo the tests with PCID, because the
>  assumptions you're basing your patch series on might actually not hold.

I'll have to do it on the bare-metal server soon anyway.

Cheers,
Willy