[THIN] Re: Hyper-Threading (again!)

  • From: "Tim Mangan" <tmangan@xxxxxxxxxxxx>
  • To: <thin@xxxxxxxxxxxxx>
  • Date: Thu, 26 Jun 2003 08:51:30 -0400

I just wanted to follow up on HT with 2000 Server, as we have finally
completed most of the testing on that platform.  As Ron has indicated, the
native OS does act badly with HT enabled.  Generally, you are better off
with HT turned off on 2000.  Don't doubt Ron!

We have added some fixes in TMuLimit that improve that situation.  The
system is now stable, we can make "user tasks" run correctly, and, we can
show improved the performance under heavy loads.  Hopefully in the future we
will find ways to fix the situation for lighter loads also.  If we do we
will post the parallel paper.  By the way, the final version of the original
paper on HT/2003 was reposted on the site, which includes a recommendation
against HT/2000 (should your customers need to see it in writing somewhere).

tim

-----Original Message-----
From: thin-bounce@xxxxxxxxxxxxx [mailto:thin-bounce@xxxxxxxxxxxxx]On
Behalf Of Ron Oglesby
Sent: Saturday, June 21, 2003 8:34 AM
To: thin@xxxxxxxxxxxxx
Subject: [THIN] Re: Hyper-Threading (again!)


Tim,=20

While I may seem to disagree with you on your "new" view I don't. I
think this will be an improvement I just wouldn't enable it on 2k.  You
paper by the way is outstanding. I have printed her out and stuck her on
the tech board in the office (stuff we post for each other to take a
look at when they get a chance).

I didn't want to seem like an old man not wanting to try anything new
for fear of loosing the old. I believe we will get an improvement out of
HyperThreading and when I tested it with scripted connections against a
2003 Terminal Server I saw about a 10% increase in user capacity with
acceptable response times in the applications.

Anyway nice to have a paper that comes in at about the same numbers.

Ron Oglesby
Senior Technical Architect
=20
RapidApp
Office 312.372.7188
Mobile 815.325.7618
email roglesby@xxxxxxxxxxxx
=20

-----Original Message-----
From: Tim Mangan [mailto:tmangan@xxxxxxxxxxxx]=20
Sent: Friday, June 20, 2003 6:46 PM
To: thin@xxxxxxxxxxxxx
Subject: [THIN] Re: Hyper-Threading (again!)

I suspect that with better hardware, the results would be different with
more processors as well. In essence, that quad 1.6Ghz looks like an
8-way
1Ghz.  The surroundings may not have been up to the task.  We all live
with
the hardware we have.  So perhaps, with some older hardware it might not
add
anything.  But if you bought a 4-way this year I would look at enabling
the
Hyper-Threading.  I have been outspoken on this list against HT in the
past -- but my thinking has turned around 180 degrees.

While the additional processors does chew up some more memory, reduced
processor queue lengths are the bennefit.

tim

-----Original Message-----
From: thin-bounce@xxxxxxxxxxxxx [mailto:thin-bounce@xxxxxxxxxxxxx]On
Behalf Of Jim Kenzig
Sent: Friday, June 20, 2003 11:36 AM
To: thin@xxxxxxxxxxxxx
Subject: [THIN] Re: Hyper-Threading (again!)


Ya, the bottom line of this doc is if you have 4 processors and turn it
on
there isn't much worth to it. With 2 processors you get about 11%
performance increase. But looking at the charts it didn't seem very
significant in any one area and appeared that quite a bit less memory
was
used if hyperthreading was turned off.
JK

-----Original Message-----
From: thin-bounce@xxxxxxxxxxxxx [mailto:thin-bounce@xxxxxxxxxxxxx]On
Behalf Of Angus Macdonald
Sent: Friday, June 20, 2003 11:24 AM
To: thin@xxxxxxxxxxxxx
Subject: [THIN] Re: Hyper-Threading (again!)


Is it just me or are the graphs on that page some of the least
informative
around?

-----Original Message-----
From: Jim Kenzig [mailto:jimkenz@xxxxxxxxxxxxxx]
Sent: 20 June 2003 16:14
To: thin@xxxxxxxxxxxxx
Subject: [THIN] Re: Hyper-Threading (again!)


I also found this recent doc from Citrix site:
CTX101880 How Hyper-Threading Affects User Capacity of Metaframe XP
Servers
http://support.citrix.com/kb/entry!default.jspa?categoryID=3D118&entryID=3D=
2
468&
fromSearchPage=3Dtrue

(link will probably wrap)
JK

-----Original Message-----
From: thin-bounce@xxxxxxxxxxxxx [mailto:thin-bounce@xxxxxxxxxxxxx]On
Behalf Of Jim Kenzig
Sent: Friday, June 20, 2003 10:17 AM
To: thin@xxxxxxxxxxxxx
Subject: [THIN] Re: Hyper-Threading (again!)


Hmm found this document on Hyperthreading support from MS
http://www.microsoft.com/whdc/hwdev/platform/proc/HT-Windows.mspx

In it states:
        All versions of the Windows 2000 operating system are fully
compliant with HT and should run without error on HT-enabled systems.
However, neither Windows 2000 nor any of its service packs support the
identification of HT processors. The type of modifications that are
required
for HT processor identification and support are not typically supported
in a
service pack. There are no plans to introduce this support in any future
Windows 2000 service pack.
        As a result, Windows 2000 treats each logical processor as if it
were an individual physical processor. The operating system attempts to
start each logical processor in the sequence in which it was listed by
the
BIOS until the number of processors that have been started is equal to
the
processor license limit for that version of the operating system. Table
1
shows the processor limits for Windows 2000 versions.

JK
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server capacity. Really get MORE from your existing servers! Free eval:
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