All of lore.kernel.org
 help / color / mirror / Atom feed
From: Ingo Molnar <mingo@kernel.org>
To: Borislav Petkov <bp@alien8.de>
Cc: Andy Lutomirski <luto@amacapital.net>,
	Dave Hansen <dave@sr71.net>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	X86 ML <x86@kernel.org>, Thomas Gleixner <tglx@linutronix.de>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	Oleg Nesterov <oleg@redhat.com>, Rik van Riel <riel@redhat.com>,
	Suresh Siddha <sbsiddha@gmail.com>,
	Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
	Fenghua Yu <fenghua.yu@intel.com>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Peter Zijlstra <a.p.zijlstra@chello.nl>
Subject: Re: [PATCH 02/19] x86, fpu: Wrap get_xsave_addr() to make it safer
Date: Fri, 29 May 2015 20:51:34 +0200	[thread overview]
Message-ID: <20150529185134.GD27501@gmail.com> (raw)
In-Reply-To: <20150529161036.GK31435@pd.tnic>


* Borislav Petkov <bp@alien8.de> wrote:

> On Thu, May 28, 2015 at 06:05:33PM -0700, Andy Lutomirski wrote:
> > I would propose that we take the opposite approach and just ban
> > eagerfpu=off when MPX is enabled.  We could then take the next step
> > and default eagerfpu=on for everyone and, if nothing breaks, then just
> > delete lazy mode entirely.
> > 
> > I suspect we'd have to go back to Pentium 3 or earlier to find a CPU
> > on which lazy mode is actually a good idea.
> 
> Last time I checked (and ran some benchmarks) it was only a minute
> slowdown so I say we kill lazy mode if it means significant code
> complexity drop.
> 
> Can I also emulate Greg here and suggest that Pentium 3 people should
> buy newer hw? They should think about the environment, if nothing else.
> 
> :-P

I went back as far as Athon64 and the CR0 manipulation and CR0 faults are overly 
expensive there too.

Ok, you guys convinced me, I'll do a patch for this in tip:x86/fpu, and then 
people can benchmark it.

Thanks,

	Ingo

  reply	other threads:[~2015-05-29 18:51 UTC|newest]

Thread overview: 42+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-05-27 18:36 [PATCH 00/19] x86, mpx updates for 4.2 (take 8) Dave Hansen
2015-05-27 18:36 ` [PATCH 01/19] x86, mpx, xsave: Fix up bad get_xsave_addr() assumptions Dave Hansen
2015-05-27 18:36 ` [PATCH 02/19] x86, fpu: Wrap get_xsave_addr() to make it safer Dave Hansen
2015-05-28  8:41   ` Ingo Molnar
2015-05-28 14:45     ` Dave Hansen
2015-05-28 15:01       ` Ingo Molnar
2015-05-28 16:02         ` Dave Hansen
2015-05-29 18:49           ` Ingo Molnar
2015-05-28 16:24         ` Dave Hansen
2015-05-29  1:05           ` Andy Lutomirski
2015-05-29 15:31             ` Dave Hansen
2015-05-29 16:10             ` Borislav Petkov
2015-05-29 18:51               ` Ingo Molnar [this message]
2015-05-29 18:17             ` Ingo Molnar
2015-05-29 18:29               ` Andy Lutomirski
2015-05-29 18:44                 ` Ingo Molnar
2015-05-29 16:47     ` Dave Hansen
2015-05-29 18:48       ` Ingo Molnar
2015-05-27 18:36 ` [PATCH 04/19] x86, mpx: Cleanup: Do not pass task around when unnecessary Dave Hansen
2015-05-27 18:36 ` [PATCH 03/19] x86, mpx: Use new get_xsave_field_ptr() Dave Hansen
2015-05-27 18:36 ` [PATCH 05/19] x86, mpx: remove redundant MPX_BNDCFG_ADDR_MASK Dave Hansen
2015-05-27 18:36 ` [PATCH 06/19] x86, mpx: Restrict mmap size check to bounds tables Dave Hansen
2015-05-27 18:36 ` [PATCH 07/19] x86, mpx: boot-time disable Dave Hansen
2015-05-27 18:36 ` [PATCH 09/19] x86, mpx: trace entry to bounds exception paths Dave Hansen
2015-05-27 18:36 ` [PATCH 10/19] x86, mpx: Trace the attempts to find bounds tables Dave Hansen
2015-05-27 18:36 ` [PATCH 12/19] x86: make is_64bit_mm() widely available Dave Hansen
2015-05-27 18:36 ` [PATCH 08/19] x86, mpx: trace #BR exceptions Dave Hansen
2015-05-27 18:36 ` [PATCH 11/19] x86, mpx: trace allocation of new bounds tables Dave Hansen
2015-05-27 18:36 ` [PATCH 14/19] x86, mpx: new directory entry to addr helper Dave Hansen
2015-05-27 18:36 ` [PATCH 13/19] x86, mpx: Add temporary variable to reduce masking Dave Hansen
2015-05-27 18:36 ` [PATCH 16/19] x86, mpx: support 32-bit binaries on 64-bit kernel Dave Hansen
2015-05-27 18:36 ` [PATCH 17/19] x86, mpx: rewrite unmap code Dave Hansen
2015-05-27 18:36 ` [PATCH 15/19] x86, mpx: do 32-bit-only cmpxchg for 32-bit apps Dave Hansen
2015-05-27 18:36 ` [PATCH 19/19] x86, mpx: allow mixed binaries again Dave Hansen
2015-05-27 18:36 ` [PATCH 18/19] x86, mpx: do not count MPX VMAs as neighbors when unmapping Dave Hansen
  -- strict thread matches above, loose matches on Subject: below --
2015-06-07 18:37 [PATCH 00/19] x86, mpx updates for 4.2 (take 9) Dave Hansen
2015-06-07 18:37 ` [PATCH 02/19] x86, fpu: Wrap get_xsave_addr() to make it safer Dave Hansen
2015-05-29 22:34 [PATCH 00/19] x86, mpx updates for 4.2 (take 8) Dave Hansen
2015-05-29 22:34 ` [PATCH 02/19] x86, fpu: Wrap get_xsave_addr() to make it safer Dave Hansen
2015-05-19  6:25 [PATCH 00/19] x86, mpx updates for 4.2 (take 7) Dave Hansen
2015-05-19  6:25 ` [PATCH 02/19] x86, fpu: Wrap get_xsave_addr() to make it safer Dave Hansen
2015-05-19  8:15   ` Thomas Gleixner
2015-05-08 18:59 [PATCH 00/19] x86, mpx updates for 4.2 (take 6) Dave Hansen
2015-05-08 18:59 ` [PATCH 02/19] x86, fpu: wrap get_xsave_addr() to make it safer Dave Hansen
2015-05-18 19:38   ` Thomas Gleixner
2015-05-18 19:42     ` Thomas Gleixner

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=20150529185134.GD27501@gmail.com \
    --to=mingo@kernel.org \
    --cc=a.p.zijlstra@chello.nl \
    --cc=bp@alien8.de \
    --cc=dave.hansen@linux.intel.com \
    --cc=dave@sr71.net \
    --cc=fenghua.yu@intel.com \
    --cc=hpa@zytor.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=luto@amacapital.net \
    --cc=mingo@redhat.com \
    --cc=oleg@redhat.com \
    --cc=riel@redhat.com \
    --cc=sbsiddha@gmail.com \
    --cc=tglx@linutronix.de \
    --cc=torvalds@linux-foundation.org \
    --cc=x86@kernel.org \
    /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.