Xen devel - Feb 2006 - Is my xen-friendly glibc really faster?

Hello all,

After compiling xen on a debian testing
mv /lib/tls /lib/tls.disabled

and in a domU I installed kde, openoffice, mozilla, etc.
Performance is not what I expected so I compiled a xen-friendly libc6

-----I copied this from the xen-users list------
Debian''s current glibc-2.3.5-6 seems to have included this patch
already.
apt-get build-dep libc6
apt-get source libc6

edit debian/rules adding
''-mno-tls-direct-seg-refs'' to BUILD_CFLAGS y HOST_CFLAGS.

dpkg-buildpackage -rfakeroot
-------thanks-----------
after installing libc6_2.3.5-13_i386.deb I don''t get that warning
anymore :)

but performance hasn''t noticeably improved.

How can I test this?
Thanks.
Chris.

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On Tuesday 21 February 2006 23:03, Chris Fanning wrote:
> After compiling xen on a debian testing
> mv /lib/tls /lib/tls.disabled
If that mv makes your system faster or slower depends entirely on your 
application. After all, this disables the NPTL thread libraries, which are 
said to give a huge performance boost (>100% in some syntetic benchmarks) to 
threaded apps.
> and in a domU I installed kde, openoffice, mozilla, etc.
> Performance is not what I expected so I compiled a xen-friendly libc6
If you run them in a domU, my guess would be the slowdown is caused by your 
VNC/NX/remote X11 connection, not from the processing in domU.
>
> -----I copied this from the xen-users list------
> Debian''s current glibc-2.3.5-6 seems to have included this patch
already.
> apt-get build-dep libc6
> apt-get source libc6
>
> edit debian/rules adding
> ''-mno-tls-direct-seg-refs'' to BUILD_CFLAGS y HOST_CFLAGS.
>
> dpkg-buildpackage -rfakeroot
> -------thanks-----------
> after installing libc6_2.3.5-13_i386.deb I don''t get that warning
anymore
> :)
>
> but performance hasn''t noticeably improved.
Well, thats the prefered solution, you get the speedups from NPTL without the 
slowdown incurred by xen''s emulation of TLS memory access.
> How can I test this?
run some benchmarks?

/Ernst

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Hi Ernst,
> If you run them in a domU, my guess would be the slowdown is caused by your
> VNC/NX/remote X11 connection, not from the processing in domU.
I had exported nfs:/home from another domU. When I moved the home
export to dom0 performance improved a lot.
Perhaps this is because of some disk access bottleneck cause buy KDE
Dcop or IPC or Unix sockets or something when running the home is on
another domU.

What do you think?

Chris.

On 2/21/06, Ernst Bachmann <e.bachmann@xebec.de>
wrote:
> On Tuesday 21 February 2006 23:03, Chris Fanning wrote:
>
> > After compiling xen on a debian testing
> > mv /lib/tls /lib/tls.disabled
>
> If that mv makes your system faster or slower depends entirely on your
> application. After all, this disables the NPTL thread libraries, which are
> said to give a huge performance boost (>100% in some syntetic
benchmarks) to
> threaded apps.
>
> > and in a domU I installed kde, openoffice, mozilla, etc.
> > Performance is not what I expected so I compiled a xen-friendly libc6
>
> If you run them in a domU, my guess would be the slowdown is caused by your
> VNC/NX/remote X11 connection, not from the processing in domU.
>
> >
> > -----I copied this from the xen-users list------
> > Debian''s current glibc-2.3.5-6 seems to have included this
patch already.
> > apt-get build-dep libc6
> > apt-get source libc6
> >
> > edit debian/rules adding
> > ''-mno-tls-direct-seg-refs'' to BUILD_CFLAGS y
HOST_CFLAGS.
> >
> > dpkg-buildpackage -rfakeroot
> > -------thanks-----------
> > after installing libc6_2.3.5-13_i386.deb I don''t get that
warning anymore
> > :)
> >
> > but performance hasn''t noticeably improved.
>
> Well, thats the prefered solution, you get the speedups from NPTL without
the
> slowdown incurred by xen''s emulation of TLS memory access.
>
> > How can I test this?
>
> run some benchmarks?
>
> /Ernst
>
> _______________________________________________
> Xen-users mailing list
> Xen-users@lists.xensource.com
> http://lists.xensource.com/xen-users
>
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On 25/02/06, Chris Fanning <christopher.fanning@gmail.com>
wrote:
> Hi Ernst,
>
> > If you run them in a domU, my guess would be the slowdown is caused by
your
> > VNC/NX/remote X11 connection, not from the processing in domU.
>
> I had exported nfs:/home from another domU. When I moved the home
> export to dom0 performance improved a lot.
> Perhaps this is because of some disk access bottleneck cause buy KDE
> Dcop or IPC or Unix sockets or something when running the home is on
> another domU.
>
> What do you think?
This was my experience as well. I discovered with Xen 2.0 using NX and
domU NFS home to another domU, that firefox cause the most drag on the
system. In general though everything was sluggish.

Moving the home dir to dom0 or native lvm device mount made that
problem go away.

The new 3.0 SMP domUs will probably be better. I haven''t had time to
experience test this yet though.


--
Nicholas Lee
http://stateless.geek.nz
gpg 8072 4F86 EDCD 4FC1 18EF  5BDD 07B0 9597 6D58 D70C

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Hi Nicholas,
> Moving the home dir to dom0 or native lvm device mount made that
> problem go away.
What do you mean by ''native''?
>
> The new 3.0 SMP domUs will probably be better. I haven''t had time
to
> experience test this yet though.
I''ve done all my testing on xen3 so it seems you need not test this yet
;)

Chris.


On 2/24/06, Nicholas Lee <emptysands@gmail.com>
wrote:
> On 25/02/06, Chris Fanning <christopher.fanning@gmail.com> wrote:
> > Hi Ernst,
> >
> > > If you run them in a domU, my guess would be the slowdown is
caused by your
> > > VNC/NX/remote X11 connection, not from the processing in domU.
> >
> > I had exported nfs:/home from another domU. When I moved the home
> > export to dom0 performance improved a lot.
> > Perhaps this is because of some disk access bottleneck cause buy KDE
> > Dcop or IPC or Unix sockets or something when running the home is on
> > another domU.
> >
> > What do you think?
>
> This was my experience as well. I discovered with Xen 2.0 using NX and
> domU NFS home to another domU, that firefox cause the most drag on the
> system. In general though everything was sluggish.
>
> Moving the home dir to dom0 or native lvm device mount made that
> problem go away.
>
> The new 3.0 SMP domUs will probably be better. I haven''t had time
to
> experience test this yet though.
>
>
> --
> Nicholas Lee
> http://stateless.geek.nz
> gpg 8072 4F86 EDCD 4FC1 18EF  5BDD 07B0 9597 6D58 D70C
>
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On 26/02/06, Chris Fanning <christopher.fanning@gmail.com>
wrote:
> Hi Nicholas,
>
> > Moving the home dir to dom0 or native lvm device mount made that
> > problem go away.
> What do you mean by ''native''?
ie. mounting the lvm slice from the host0 direct using disks = [...].

> I''ve done all my testing on xen3 so it seems you need not test
this yet ;)
Interesting as the network performance in Xen 3.0 between domUs does
seem better, at least for scp.  I guess there is still latency issues.

--
Nicholas Lee
http://stateless.geek.nz
gpg 8072 4F86 EDCD 4FC1 18EF  5BDD 07B0 9597 6D58 D70C

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Hi,
I want to know whether a KDB patch of xen 3.0 exists for linux 2.6.12.
Any pointers on this regard will be useful.
TIA,
- Abhijit 

NOTE: In the mail-group, I found that kdb patch of xen 2.0.3 is
available for linux 2.6.10:
http://lists.xensource.com/archives/html/xen-devel/2005-01/msg00834.html


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