A
Andrew Maclean
Does VC7.1 support hyperthreading?
I looked in the documentation but I could find no reference at all.
I looked in the documentation but I could find no reference at all.
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C
Carl Daniel [VC++ MVP]
Andrew said:Does VC7.1 support hyperthreading?
I looked in the documentation but I could find no reference at all.
Hyperthreading is supported by Windows XP, Windows 2000 SP3 (I believe) and
Windows Server 2003. There's no compiler support necessary. The
OS-provided support simply exposes multiple "virtual processors", so a
machine with a single HT-capable CPU will appear to have two processors.
-cd
J
John Smith
Hyperthreading is supported by Windows XP, Windows 2000 SP3 (I believe)
and
Intel recommends that Hyper-Threading should be disabled for *all* Win2000
systems (at least it's still posted at their site)
and
Windows Server 2003. There's no compiler support necessary. The
OS-provided support simply exposes multiple "virtual processors", so a
machine with a single HT-capable CPU will appear to have two processors.
Intel recommends that Hyper-Threading should be disabled for *all* Win2000
systems (at least it's still posted at their site)
T
Tomas Restrepo \(MVP\)
Hi John,
Weird. Anyway, for anyone interested in this, there's a good article (albeit
a little bit old) from MS regardgin HT support for windows here:
http://www.microsoft.com/windows2000/server/evaluation/performance/reports/hyperthread.asp
Intel recommends that Hyper-Threading should be disabled for *all* Win2000
systems (at least it's still posted at their site)
Weird. Anyway, for anyone interested in this, there's a good article (albeit
a little bit old) from MS regardgin HT support for windows here:
http://www.microsoft.com/windows2000/server/evaluation/performance/reports/hyperthread.asp
J
John Smith
T
Tomas Restrepo \(MVP\)
Hi John,
Sounds like a little FUD to me. The page clearly mentions at the begining
that it references OSs with HT optimizations, which indeed Win2k doesn't
have. In particular, it has two problems:
1- It cannot distinguish between logical and physical processors, which has
licensing issues
2- because of 1, the OS doesn't take into account the difference when
scheduling threads, leading to sub-optimal scheduling (because of possible
extra context changes when moving threads between physical processors)
It works, though, from what little I've seen...
Sounds like a little FUD to me. The page clearly mentions at the begining
that it references OSs with HT optimizations, which indeed Win2k doesn't
have. In particular, it has two problems:
1- It cannot distinguish between logical and physical processors, which has
licensing issues
2- because of 1, the OS doesn't take into account the difference when
scheduling threads, leading to sub-optimal scheduling (because of possible
extra context changes when moving threads between physical processors)
It works, though, from what little I've seen...
S
Stephan Schaem
John Smith said:Intel recommends that Hyper-Threading should be disabled for *all* Win2000
systems (at least it's still posted at their site)
I use XP and disabled HT because it seem compile time goes up with it enabled.
I turn it on for testing/bebugging purposes (short of using a dual processor system)
So I'm not sure VC7.1 is multithreaded optimized. (compile process)
What I noticed also in the compile process is bunch of dead CPU time,
so I'm guessing the the compiler dont build an async queue of file to read/write ?
Stephan
C
Carl Daniel [VC++ MVP]
Stephan said:I use XP and disabled HT because it seem compile time goes up with it
enabled.
I turn it on for testing/bebugging purposes (short of using a dual
processor system)
So I'm not sure VC7.1 is multithreaded optimized. (compile process)
What I noticed also in the compile process is bunch of dead CPU time,
so I'm guessing the the compiler dont build an async queue of file to
read/write ?
Correct. The compiler is a completely synchronous, single-threaded process.
I use XP and leave hyperthreading enabled because I feel that it improves
overall system performance, especially when running a compute-intensive
application. The performance of a single-threaded application will likely
be lower with HT enabled, but the impact that compute-intensive process has
on system responsiveness (mouse responsiveness, for example) is greatly
reduced over the non-HT case.
-cd
P
Pent
Whidbey alpha has support for maximum concurrent builds. And you can specify
how many. It's pretty nice for HT and more than one CPUs.
how many. It's pretty nice for HT and more than one CPUs.