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From: Tamas K Lengyel <tamas.k.lengyel@gmail.com>
To: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: mpohlack@amazon.de, "Julien Grall" <julien.grall@arm.com>,
	"Jan Beulich" <JBeulich@suse.com>,
	joao.m.martins@oracle.com,
	"Stefano Stabellini" <sstabellini@kernel.org>,
	"Daniel Kiper" <daniel.kiper@oracle.com>,
	"Marek Marczykowski-Górecki" <marmarek@invisiblethingslab.com>,
	aliguori@amazon.com, uwed@amazon.de,
	"Lars Kurth" <lars.kurth@citrix.com>,
	"Konrad Rzeszutek Wilk" <konrad.wilk@oracle.com>,
	ross.philipson@oracle.com, "Dario Faggioli" <dfaggioli@suse.com>,
	msw@amazon.com, "Boris Ostrovsky" <boris.ostrovsky@oracle.com>,
	JGross@suse.com, sergey.dyasli@citrix.com,
	"Wei Liu" <wei.liu2@citrix.com>,
	"George Dunlap" <george.dunlap@eu.citrix.com>,
	Xen-devel <xen-devel@lists.xen.org>,
	mdontu <mdontu@bitdefender.com>,
	dwmw@amazon.co.uk, "Roger Pau Monné" <roger.pau@citrix.com>
Subject: Re: Ongoing/future speculative mitigation work
Date: Wed, 24 Oct 2018 09:24:32 -0600	[thread overview]
Message-ID: <CABfawh=GYUi2nvx5Nc1xfu7McVSqCwYOMyA6fyCKgYJCGCRkXA@mail.gmail.com> (raw)
In-Reply-To: <e3219697-0759-39fc-2486-715cdec1ca9e@citrix.com>

> A solution to this issue was proposed, whereby Xen synchronises siblings
> on vmexit/entry, so we are never executing code in two different
> privilege levels.  Getting this working would make it safe to continue
> using hyperthreading even in the presence of L1TF.  Obviously, its going
> to come in perf hit, but compared to disabling hyperthreading, all its
> got to do is beat a 60% perf hit to make it the preferable option for
> making your system L1TF-proof.

Could you shed some light what tests were done where that 60%
performance hit was observed? We have performed intensive stress-tests
to confirm this but according to our findings turning off
hyper-threading is actually improving performance on all machines we
tested thus far.

Thanks,
Tamas

_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xenproject.org
https://lists.xenproject.org/mailman/listinfo/xen-devel

  parent reply	other threads:[~2018-10-24 15:24 UTC|newest]

Thread overview: 63+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-10-18 17:46 Ongoing/future speculative mitigation work Andrew Cooper
2018-10-19  8:09 ` Dario Faggioli
2018-10-19 12:17   ` Andrew Cooper
2018-10-22  9:32     ` Mihai Donțu
2018-10-22 14:55 ` Wei Liu
2018-10-22 15:09   ` Woodhouse, David
2018-10-22 15:14     ` Andrew Cooper
2018-10-25 14:50   ` Jan Beulich
2018-10-25 14:56     ` George Dunlap
2018-10-25 15:02       ` Jan Beulich
2018-10-25 16:29         ` Andrew Cooper
2018-10-25 16:43           ` George Dunlap
2018-10-25 16:50             ` Andrew Cooper
2018-10-25 17:07               ` George Dunlap
2018-10-26  9:16           ` Jan Beulich
2018-10-26  9:28             ` Wei Liu
2018-10-26  9:56               ` Jan Beulich
2018-10-26 10:51                 ` George Dunlap
2018-10-26 11:20                   ` Jan Beulich
2018-10-26 11:24                     ` George Dunlap
2018-10-26 11:33                       ` Jan Beulich
2018-10-26 11:43                         ` George Dunlap
2018-10-26 11:45                           ` Jan Beulich
2018-12-11 18:05                     ` Wei Liu
     [not found]                       ` <FB70ABC00200007CA293CED3@prv1-mh.provo.novell.com>
2018-12-12  8:32                         ` Jan Beulich
2018-10-24 15:24 ` Tamas K Lengyel [this message]
2018-10-25 16:01   ` Dario Faggioli
2018-10-25 16:25     ` Tamas K Lengyel
2018-10-25 17:23       ` Dario Faggioli
2018-10-25 17:29         ` Tamas K Lengyel
2018-10-26  7:31           ` Dario Faggioli
2018-10-25 16:55   ` Andrew Cooper
2018-10-25 17:01     ` George Dunlap
2018-10-25 17:35       ` Tamas K Lengyel
2018-10-25 17:43         ` Andrew Cooper
2018-10-25 17:58           ` Tamas K Lengyel
2018-10-25 18:13             ` Andrew Cooper
2018-10-25 18:35               ` Tamas K Lengyel
2018-10-25 18:39                 ` Andrew Cooper
2018-10-26  7:49                 ` Dario Faggioli
2018-10-26 12:01                   ` Tamas K Lengyel
2018-10-26 14:17                     ` Dario Faggioli
2018-10-26 10:11               ` George Dunlap
2018-12-07 18:40 ` Wei Liu
2018-12-10 12:12   ` George Dunlap
2018-12-10 12:19     ` George Dunlap
2019-01-24 11:44 ` Reducing or removing direct map from xen (was Re: Ongoing/future speculative mitigation work) Wei Liu
2019-01-24 16:00   ` George Dunlap
2019-02-07 16:50   ` Wei Liu
2019-02-20 12:29   ` Wei Liu
2019-02-20 13:00     ` Roger Pau Monné
2019-02-20 13:09       ` Wei Liu
2019-02-20 17:08         ` Wei Liu
2019-02-21  9:59           ` Roger Pau Monné
2019-02-21 17:51             ` Wei Liu
2019-02-22 11:48           ` Jan Beulich
2019-02-22 11:50             ` Wei Liu
2019-02-22 12:06               ` Jan Beulich
2019-02-22 12:11                 ` Wei Liu
2019-02-22 12:47                   ` Jan Beulich
2019-02-22 13:19                     ` Wei Liu
     [not found]                       ` <158783E402000088A293CED3@prv1-mh.provo.novell.com>
2019-02-22 13:24                         ` Jan Beulich
2019-02-22 13:27                           ` Jan Beulich

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