From: Josh Poimboeuf <jpoimboe@redhat.com>
To: speck@linutronix.de
Subject: [MODERATED] Re: [PATCH v5 14/27] MDSv5 3
Date: Wed, 23 Jan 2019 16:57:14 -0600 [thread overview]
Message-ID: <20190123225714.ybjfxcckmxiez2mi@treble> (raw)
In-Reply-To: <20190123224004.ekqtemmu44vnnuoh@treble>
On Wed, Jan 23, 2019 at 04:40:04PM -0600, Josh Poimboeuf wrote:
> On Wed, Jan 23, 2019 at 08:02:06AM -0800, speck for Andi Kleen wrote:
> > > you just sprinkle random mitigation calls around.
> > >
> > > The point is that paranoid mitigation is simply 'always invoke VERW'. The
> > > conditional modes and that's what we have done for the other
> > > vulnerabilities as well are handling the most obvious issues and leave some
> > > documented holes. Trying to catch everything in cond mode is just adding a
> > > lot of pointless crap all over the code base and will still fail to plug
> > > all holes unless you do a full audit of all kernel code.
> > >
> > > It would be interesting to see the following test results:
> >
> > You mean performance test results? That's in 0/0
> >
> > The worse case slow down we've seen with the lazy flushing
> > is ~2% (on a benchmark that pushes data over loopback
> > in a tight loop). Most workloads see no change because
> > the existing lazy scheme works fairly well.
> >
> > With full flushing the worst case seen is 8%, but again
> > that was a workload that does syscalls in a tight loop,
> > so more an outlier.
>
> We're actually seeing some very large slowdowns -- much worse than 8%.
>
> The early results are showing more like 130% slowdown in several cases
> for mds=full.
>
> The mds=auto tests are in progress.
>
> I don't have much more detail than that at the moment, but I can try to
> provide more details about the benchmarks when I get them.
>
> It would be interesting to see if others are seeing similar results.
> This is on a 4.18-based RHEL kernel.
So these 130+% slowdowns were microbenchmarks which call a syscall in a
tight loop. I can provide a reproducer shortly.
The default (mds=auto?) results will be available soon; apparently they
are looking much better.
--
Josh
next prev parent reply other threads:[~2019-01-23 22:57 UTC|newest]
Thread overview: 105+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-19 0:50 [MODERATED] [PATCH v5 00/27] MDSv5 19 Andi Kleen
2019-01-19 0:50 ` [MODERATED] [PATCH v5 01/27] MDSv5 26 Andi Kleen
2019-01-22 4:17 ` [MODERATED] " Konrad Rzeszutek Wilk
2019-01-22 12:46 ` Thomas Gleixner
2019-01-19 0:50 ` [MODERATED] [PATCH v5 02/27] MDSv5 14 Andi Kleen
2019-01-22 4:20 ` [MODERATED] " Konrad Rzeszutek Wilk
2019-01-22 12:51 ` Thomas Gleixner
2019-01-19 0:50 ` [MODERATED] [PATCH v5 03/27] MDSv5 16 Andi Kleen
2019-01-22 4:23 ` [MODERATED] " Konrad Rzeszutek Wilk
2019-01-22 12:55 ` Thomas Gleixner
2019-01-27 21:58 ` Thomas Gleixner
2019-01-28 3:30 ` [MODERATED] " Andi Kleen
2019-01-19 0:50 ` [MODERATED] [PATCH v5 04/27] MDSv5 15 Andi Kleen
2019-01-22 4:33 ` [MODERATED] " Konrad Rzeszutek Wilk
2019-01-22 12:59 ` Thomas Gleixner
2019-01-19 0:50 ` [MODERATED] [PATCH v5 05/27] MDSv5 21 Andi Kleen
2019-01-22 4:35 ` [MODERATED] " Konrad Rzeszutek Wilk
2019-01-22 13:01 ` Thomas Gleixner
2019-02-21 12:06 ` Thomas Gleixner
2019-01-19 0:50 ` [MODERATED] [PATCH v5 06/27] MDSv5 18 Andi Kleen
2019-01-21 22:41 ` [MODERATED] " Josh Poimboeuf
2019-01-22 1:16 ` Andi Kleen
2019-01-19 0:50 ` [MODERATED] [PATCH v5 07/27] MDSv5 0 Andi Kleen
2019-01-22 4:39 ` [MODERATED] " Konrad Rzeszutek Wilk
2019-01-27 22:09 ` Thomas Gleixner
2019-01-28 3:33 ` [MODERATED] " Andi Kleen
2019-01-28 8:29 ` Thomas Gleixner
2019-02-13 22:26 ` [MODERATED] " Tyler Hicks
2019-01-19 0:50 ` [MODERATED] [PATCH v5 08/27] MDSv5 13 Andi Kleen
2019-01-22 4:40 ` [MODERATED] " Konrad Rzeszutek Wilk
2019-01-19 0:50 ` [MODERATED] [PATCH v5 09/27] MDSv5 23 Andi Kleen
2019-01-22 4:56 ` [MODERATED] " Konrad Rzeszutek Wilk
2019-01-22 7:26 ` Greg KH
2019-01-22 13:07 ` Thomas Gleixner
2019-01-19 0:50 ` [MODERATED] [PATCH v5 10/27] MDSv5 7 Andi Kleen
2019-01-19 0:50 ` [MODERATED] [PATCH v5 11/27] MDSv5 2 Andi Kleen
2019-01-22 13:11 ` Thomas Gleixner
2019-01-19 0:50 ` [MODERATED] [PATCH v5 12/27] MDSv5 6 Andi Kleen
2019-01-22 14:01 ` Thomas Gleixner
2019-01-22 15:42 ` Thomas Gleixner
2019-01-22 18:01 ` [MODERATED] " Andi Kleen
2019-01-19 0:50 ` [MODERATED] [PATCH v5 13/27] MDSv5 17 Andi Kleen
2019-01-19 0:50 ` [MODERATED] [PATCH v5 14/27] MDSv5 3 Andi Kleen
2019-01-22 4:48 ` [MODERATED] " Konrad Rzeszutek Wilk
2019-01-22 15:58 ` Thomas Gleixner
2019-01-22 17:57 ` Thomas Gleixner
2019-01-23 1:35 ` [MODERATED] " Andi Kleen
2019-01-23 9:27 ` Thomas Gleixner
2019-01-23 16:02 ` [MODERATED] " Andi Kleen
2019-01-23 22:40 ` Josh Poimboeuf
2019-01-23 22:57 ` Josh Poimboeuf [this message]
2019-01-24 0:25 ` Josh Poimboeuf
2019-01-24 2:26 ` Andi Kleen
2019-01-24 12:04 ` Thomas Gleixner
2019-01-28 3:42 ` [MODERATED] " Andi Kleen
2019-01-28 8:33 ` Thomas Gleixner
2019-02-16 2:00 ` [MODERATED] " Andi Kleen
2019-02-16 10:32 ` Thomas Gleixner
2019-02-16 16:58 ` [MODERATED] " Andi Kleen
2019-02-16 17:12 ` Andi Kleen
2019-01-19 0:50 ` [MODERATED] [PATCH v5 15/27] MDSv5 1 Andi Kleen
2019-01-22 4:48 ` [MODERATED] " Konrad Rzeszutek Wilk
2019-01-19 0:50 ` [MODERATED] [PATCH v5 16/27] MDSv5 10 Andi Kleen
2019-01-22 4:54 ` [MODERATED] " Konrad Rzeszutek Wilk
2019-01-22 7:33 ` Greg KH
2019-01-19 0:50 ` [MODERATED] [PATCH v5 17/27] MDSv5 9 Andi Kleen
2019-01-19 0:50 ` [MODERATED] [PATCH v5 18/27] MDSv5 8 Andi Kleen
2019-01-22 5:07 ` [MODERATED] " Konrad Rzeszutek Wilk
2019-01-19 0:50 ` [MODERATED] [PATCH v5 19/27] MDSv5 12 Andi Kleen
2019-01-22 5:09 ` [MODERATED] " Konrad Rzeszutek Wilk
2019-01-19 0:50 ` [MODERATED] [PATCH v5 20/27] MDSv5 27 Andi Kleen
2019-01-19 0:50 ` [MODERATED] [PATCH v5 21/27] MDSv5 20 Andi Kleen
2019-01-22 5:11 ` [MODERATED] " Konrad Rzeszutek Wilk
2019-01-19 0:50 ` [MODERATED] [PATCH v5 22/27] MDSv5 24 Andi Kleen
2019-01-21 21:24 ` [MODERATED] " Linus Torvalds
2019-01-22 1:22 ` Andi Kleen
2019-01-22 16:09 ` Thomas Gleixner
2019-01-22 17:56 ` [MODERATED] " Andi Kleen
2019-01-22 18:56 ` Thomas Gleixner
2019-01-23 1:39 ` [MODERATED] " Andi Kleen
2019-01-23 6:39 ` Greg KH
2019-01-24 9:55 ` Thomas Gleixner
2019-01-19 0:50 ` [MODERATED] [PATCH v5 23/27] MDSv5 22 Andi Kleen
2019-01-19 0:50 ` [MODERATED] [PATCH v5 24/27] MDSv5 5 Andi Kleen
2019-01-21 21:20 ` [MODERATED] " Linus Torvalds
2019-01-19 0:50 ` [MODERATED] [PATCH v5 25/27] MDSv5 4 Andi Kleen
2019-01-22 5:15 ` [MODERATED] " Konrad Rzeszutek Wilk
2019-01-19 0:50 ` [MODERATED] [PATCH v5 26/27] MDSv5 11 Andi Kleen
2019-01-19 0:50 ` [MODERATED] [PATCH v5 27/27] MDSv5 25 Andi Kleen
2019-01-21 21:18 ` [MODERATED] Re: [PATCH v5 00/27] MDSv5 19 Linus Torvalds
2019-01-22 1:14 ` Andi Kleen
2019-01-22 7:38 ` Greg KH
2019-01-28 11:34 ` Thomas Gleixner
2019-02-13 22:33 ` [MODERATED] " Tyler Hicks
2019-02-14 13:09 ` Jiri Kosina
2019-02-14 13:51 ` Greg KH
2019-02-14 16:53 ` Andi Kleen
2019-02-14 18:00 ` Greg KH
2019-02-14 18:05 ` Andrew Cooper
2019-02-14 18:33 ` Andi Kleen
2019-02-14 18:52 ` Greg KH
2019-02-14 19:50 ` Andi Kleen
2019-02-15 7:06 ` Greg KH
2019-02-15 13:06 ` Andi Kleen
2019-02-19 12:12 ` Greg KH
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20190123225714.ybjfxcckmxiez2mi@treble \
--to=jpoimboe@redhat.com \
--cc=speck@linutronix.de \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.