LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Zachary Amsden <zach@vmware.com>
To: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Andi Kleen <ak@muc.de>, Andrew Morton <akpm@osdl.org>,
	linux-kernel@vger.kernel.org, virtualization@lists.osdl.org,
	xen-devel@lists.xensource.com, Chris Wright <chrisw@sous-sol.org>,
	Ian Pratt <ian.pratt@xensource.com>,
	Christian Limpach <Christian.Limpach@cl.cam.ac.uk>
Subject: Re: [patch 13/21] Xen-paravirt: Add nosegneg capability to the vsyscall page notes
Date: Tue, 13 Feb 2007 14:45:43 -0800	[thread overview]
Message-ID: <45D23F97.5040907@vmware.com> (raw)
In-Reply-To: <20070213221830.466651996@goop.org>

Jeremy Fitzhardinge wrote:
> Add the "nosegneg" fake capabilty to the vsyscall page notes. This is
> used by the runtime linker to select a glibc version which then
> disables negative-offset accesses to the thread-local segment via
> %gs. These accesses require emulation in Xen (because segments are
> truncated to protect the hypervisor address space) and avoiding them
> provides a measurable performance boost.
>   

I don't like this because now a kernel compiled with both CONFIG_XEN and 
CONFIG_VMI has "nosegneg" turned on.  We don't actually require this for 
performance or correctness, so it would be nice to be able to 
dynamically turn it off instead of having it forced.

Zach

  parent reply	other threads:[~2007-02-13 22:45 UTC|newest]

Thread overview: 46+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20070213221729.772002682@goop.org>
     [not found] ` <20070213221829.929261125@goop.org>
2007-02-13 22:39   ` [patch 06/21] Xen-paravirt: remove ctor for pgd cache Zachary Amsden
     [not found] ` <20070213221830.466651996@goop.org>
2007-02-13 22:45   ` Zachary Amsden [this message]
2007-02-13 22:49     ` [patch 13/21] Xen-paravirt: Add nosegneg capability to the vsyscall page notes Jeremy Fitzhardinge
2007-02-13 22:54       ` Zachary Amsden
2007-02-13 23:13         ` Jeremy Fitzhardinge
2007-02-14  5:38     ` [Xen-devel] " Rusty Russell
     [not found] ` <20070213221830.542511707@goop.org>
2007-02-13 22:53   ` [patch 14/21] Xen-paravirt: Add XEN config options and disable unsupported config options Dan Hecht
2007-02-13 23:29     ` Jeremy Fitzhardinge
2007-02-13 23:58       ` [Xen-devel] " Zachary Amsden
2007-02-13 23:58       ` Dan Hecht
     [not found] ` <20070213221830.238235953@goop.org>
2007-02-14  1:06   ` [patch 10/21] Xen-paravirt: Name: dont export paravirt_ops structure, do individual functions Zachary Amsden
2007-02-14  1:16     ` Jeremy Fitzhardinge
2007-02-14  1:18       ` Zachary Amsden
2007-02-14  1:37         ` Jeremy Fitzhardinge
2007-02-14  1:43           ` Zachary Amsden
2007-02-14  1:44             ` Jeremy Fitzhardinge
2007-02-14  5:51     ` Rusty Russell
2007-02-14 19:36     ` Christoph Hellwig
     [not found] ` <20070213221829.845132535@goop.org>
2007-02-14  1:23   ` [patch 05/21] Xen-paravirt: paravirt_ops: allocate a fixmap slot Dan Hecht
2007-02-14  1:36     ` Jeremy Fitzhardinge
2007-02-14  2:34       ` Dan Hecht
2007-02-14  8:43         ` Gerd Hoffmann
2007-02-14  8:37       ` [Xen-devel] " Jan Beulich
2007-02-14  9:15         ` Andi Kleen
     [not found] ` <20070213221829.513618819@goop.org>
2007-02-14  9:24   ` [patch 02/21] Xen-paravirt: Handle a zero-sized VT console Gerd Hoffmann
     [not found] ` <20070213221830.707197267@goop.org>
2007-02-13 23:54   ` [patch 16/21] Xen-paravirt: Add code into head.S to handle being booted by Xen Andi Kleen
2007-02-14  0:39     ` Jeremy Fitzhardinge
2007-02-14  8:56       ` [Xen-devel] " Jan Beulich
2007-02-14 18:53     ` Jeremy Fitzhardinge
2007-02-14 20:10       ` Eric W. Biederman
2007-02-14 20:41         ` Jeremy Fitzhardinge
2007-02-14 21:06           ` Eric W. Biederman
2007-02-15  0:13             ` Jeremy Fitzhardinge
2007-02-15  1:39               ` Eric W. Biederman
2007-02-15  1:52                 ` Jeremy Fitzhardinge
2007-02-15  2:18                   ` Eric W. Biederman
2007-02-15  2:23                     ` Jeremy Fitzhardinge
2007-02-15  2:41                       ` Eric W. Biederman
2007-02-14 20:33   ` Eric W. Biederman
2007-02-14 20:42     ` Jeremy Fitzhardinge
     [not found] ` <20070213221831.150207238@goop.org>
2007-02-14 20:40   ` [patch 21/21] Xen-paravirt: Add the Xen virtual network device driver Eric W. Biederman
     [not found] ` <20070213221830.619562494@goop.org>
2007-02-14 20:45   ` [patch 15/21] Xen-paravirt: Add Xen interface header files Eric W. Biederman
2007-02-15  0:10     ` Jeremy Fitzhardinge
2007-02-15 17:32       ` Christoph Hellwig
2007-02-16  2:24 [patch 00/21] Xen-paravirt: Xen guest implementation for paravirt_ops interface Jeremy Fitzhardinge
2007-02-16  2:25 ` [patch 13/21] Xen-paravirt: Add nosegneg capability to the vsyscall page notes Jeremy Fitzhardinge
2007-02-16  6:06   ` Zachary Amsden

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=45D23F97.5040907@vmware.com \
    --to=zach@vmware.com \
    --cc=Christian.Limpach@cl.cam.ac.uk \
    --cc=ak@muc.de \
    --cc=akpm@osdl.org \
    --cc=chrisw@sous-sol.org \
    --cc=ian.pratt@xensource.com \
    --cc=jeremy@goop.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=virtualization@lists.osdl.org \
    --cc=xen-devel@lists.xensource.com \
    --subject='Re: [patch 13/21] Xen-paravirt: Add nosegneg capability to the vsyscall page notes' \
    /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

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).