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Re: [Xen-users] /lib/tls.disabled does not work

To: XEN-Users <xen-users@xxxxxxxxxxxxxxxxxxx>
Subject: Re: [Xen-users] /lib/tls.disabled does not work
From: William Zhou <armageddonmagic@xxxxxxx>
Date: Sun, 16 Apr 2006 00:29:37 +0100
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Ralf Schmitt wrote:
Hi,

a new initrd will not help. Have a look a this:

***************************************************************
***************************************************************
** WARNING: Currently emulating unsupported memory accesses  **
**          in /lib/tls glibc libraries. The emulation is    **
**          slow. To ensure full performance you should      **
**          install a 'xen-friendly' (nosegneg) version of   **
**          the library, or disable tls support by executing **
**          the following as root:                           **
**          mv /lib/tls /lib/tls.disabled                    **
** Offending process: hotplug (pid=276)                      **
***************************************************************
***************************************************************

This message comes from "hotplug" ... so I have to compile hotplug
without tls support to get rid of this boot message.

Move /lib/tls to /ib/tls.disabled and ignore these messages.

-ralf-
Every package built without -mno-tls-direct-seg-refs has this problem, including Glibc. Gentoo chooses to rebuild the whole tree to get rid of this problem. Taken from Gentoo Wiki:

"Some software, in particular the glibc TLS library, performs poorly whilst carrying out certain operations under Xen. This will result in a ~50% performance penalty running multi-threaded applications. To fix this, you must compile your system with the '-mno-tls-direct-seg-refs' flag. Rebuild every package with your new CFLAGS."

Gentoo also choose to use Glibc with NPTL only, without Linuxthread. This eliminates
the use of directory /lib/tls.


William Zhou


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