Dual Core Opteron and Java threads

A

Andy

I'm Considering a new workstation with 2 dual core opterons running
FC4. I'm wondering if anybody has had any experience with an
architecture like this, and had any comments on any known issues?
Specifically regarding Java threads, how the VM treats each core in
terms of SMP (recognizing the entire system as 2- way processing or
4-way processing?), memory issues, etc?

Thanks in advance,

Andy
 
D

Dimitri Maziuk

Andy sez:
I'm Considering a new workstation with 2 dual core opterons running
FC4. I'm wondering if anybody has had any experience with an
architecture like this, and had any comments on any known issues?
Specifically regarding Java threads, how the VM treats each core in
terms of SMP (recognizing the entire system as 2- way processing or
4-way processing?), memory issues, etc?

Don't have any dual-cores, but until 2.6.15 our 2 single core opterons
were dropping tcp connections at random. That's on two fairly lightly
loaded webservers and one development machine. So the first thing you'll
want to do is install 2.6.15 kernel from updates.

Didn't notice anything special about Java apps -- except of course
FC4 comes with (unusable) gcj that everything else depends on and
with Debian's alternatives system from hell. Thankfully, jpackage
does a good job at rolling Sun's 1.5 tarball into rpms that install
properly (as in don't conflict with gcj and update /etc/alternatives
correctly).

Dima
 
L

lewmania942

Don't have any dual-cores, but until 2.6.15 our 2 single core opterons
were dropping tcp connections at random. That's on two fairly lightly
loaded webservers and one development machine.

Interesting. But do you /really/ use FC4 on a production machine?

(I use FC4 on my main development machine, but even if that
machine has uptime in months [yup, months] I wouldn't use
FC4 for a production system)

Didn't notice anything special about Java apps -- except of course
FC4 comes with (unusable) gcj that everything else depends on and
with Debian's alternatives system from hell. Thankfully, jpackage
does a good job at rolling Sun's 1.5 tarball into rpms that install
properly (as in don't conflict with gcj and update /etc/alternatives
correctly).

rpm means needing to be root to install the package (one
major drawback of the rpm packaging system).

I prefer a tarball that can be installed in userland over
an rpm that mandates root.

It's also way easier to play/test/swap/upgrade when needing
to work with different virtual machines (1.4, 1.5, beta 1.6,
IBM, etc.).

That said, YMMV.

:)
 
D

Dimitri Maziuk

(e-mail address removed) sez:
Interesting. But do you /really/ use FC4 on a production machine?

Not much choice: we have to run a binary-only app on the backend,
and the only x86 binary available is Linux. I'm getting the authors
to build a x86 Solaris version, in the meantime, Linux it is. AMDs
are not that well supported by 2.4 kernels, so it should to be a
2.6-based distro. We've been using dead rat since 6.2 and I haven't
seen anything that would objectively prove FC worse (or better)
than any other 2.6-based distro.
(I use FC4 on my main development machine, but even if that
machine has uptime in months [yup, months] I wouldn't use
FC4 for a production system)

dmaziuk@yellowtail:~% uname -a
Linux yellowtail.bmrb.wisc.edu 2.6.11-1.27_FC3 #1 Tue May 17 \
20:27:37 EDT 2005 i686 i686 i386 GNU/Linux
dmaziuk@yellowtail:~% uptime
18:38:48 up 207 days, 2:03, 9 users, load average: 0.00, 0.02, 0.07

;) (I'd bump it to 4, but then I'd lose the uptime.)

Seriously, though, the problem is SMP, AMD, or both. Linux has been
stable enough for production use on single Intel chips for years.

Dima
 
P

Pedro

Hi,

I am about to make a Linux Dual Core system.
Did anyone of you tested with SuSE OSS or with the more server-like CentOS
distribution?


(e-mail address removed) sez:

Not much choice: we have to run a binary-only app on the backend,
and the only x86 binary available is Linux. I'm getting the authors
to build a x86 Solaris version, in the meantime, Linux it is. AMDs
are not that well supported by 2.4 kernels, so it should to be a
2.6-based distro. We've been using dead rat since 6.2 and I haven't
seen anything that would objectively prove FC worse (or better)
than any other 2.6-based distro.

How many distros did you tried?
It is really important to know this detail.
And apart from the tcp drops did you tried any up-date to patch.
I have not seen any coments on that on the net.
I am starting to became concerned abou it ...
(I use FC4 on my main development machine, but even if that
machine has uptime in months [yup, months] I wouldn't use
FC4 for a production system)

dmaziuk@yellowtail:~% uname -a
Linux yellowtail.bmrb.wisc.edu 2.6.11-1.27_FC3 #1 Tue May 17 \
20:27:37 EDT 2005 i686 i686 i386 GNU/Linux
dmaziuk@yellowtail:~% uptime
18:38:48 up 207 days, 2:03, 9 users, load average: 0.00, 0.02, 0.07

;) (I'd bump it to 4, but then I'd lose the uptime.)

Seriously, though, the problem is SMP, AMD, or both. Linux has been
stable enough for production use on single Intel chips for years.

If you notice the Open source only version in Suse Linux site:
http://www.novell.com/coolsolutions/tip/16015.html

One can compare with the"full" version:
http://www.novell.com/products/linuxpackages/professional/index.html

and see that some packages for smp are not present.
I am not sure if the x86_64 is really equivalent as the i586
packages mentioned on the page.
But if it is the OSS version lacks the following packages that can make
the diference ...

kernel-bigsmp-nongpl-2.6.13-15.i586.rpm
kernel-default-nongpl-2.6.1 3-15.i586.rpm
kernel-smp-nongpl-2.6.13-15.i586.rpm
kernel-um-nongpl-2 .6.13-15.i586.rpm
kernel-xen-nongpl-2.6.13-15.i586.rpm (this one is just for xen
installations)

Not to mention that aparently the JVM is not 1.5 the one suposely
"optimized" for 64 bit and Dual Core.

It is missing:

java-1_4_2-gcj-compat-1.4.2.0-9.i586.rpm
java-1_4_2-g cj-compat-devel-1.4.2.0-9.i586.rpm
java-1_4_2-sun-1.4.2.06-5.i586.rpm
java-1_4_2-sun-alsa-1.4.2.06-5.i586.rpm
java-1_4_2-sun-demo-1.4.2.06-5. i586.rpm
java-1_4_2-sun-devel-1.4.2.06-5.i586.rpm
java-1_4_2-sun-jdbc -1.4.2.06-5.i586.rpm
java-1_4_2-sun-plugin-1.4.2.06-5.i586.rpm
java-1 _4_2-sun-src-1.4.2.06-5.i586.rpm
java-1_5_0-sun-1.5.0_03-2.i586.rpm
j ava-1_5_0-sun-alsa-1.5.0_03-2.i586.rpm
java-1_5_0-sun-demo-1.5.0_03-2.i5 86.rpm
java-1_5_0-sun-devel-1.5.0_03-2.i586.rpm
java-1_5_0-sun-jdbc-1 .5.0_03-2.i586.rpm
java-1_5_0-sun-plugin-1.5.0_03-2.i586.rpm

I did not check FC but I suspect FC4 might have the same sort of problems ...

Regards,
Pedro
 
A

Andy

....
And apart from the tcp drops did you tried any up-date to patch.
I have not seen any coments on that on the net.
I am starting to became concerned abou it ...
....

This is somthing that I'm a little worried about too. I've heard that
the Install for FC4 is not exactly an out of the box for 2 dual core
opterons. Something about installing for a single processor, and then
rebuilding the kernal SMP. I dont know the details, but if this is so,
I'm wondering how stable the up2date patches will be.
 

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