@MikeB

Quote:

The advantages in Windows of having multi-core improved over time. Multi-threading is needed for that. For the OS itself to take well advantage of multi-cores vs performance in a single core environment must include multi-processing abilities for core processes.

Windows was multithreaded a very long time before dual core processors got made, WindowsNT was running on multi-CPU systems for ages. The home OSes could run across multiple cores since Windows 2k. Some processes and services of the OS might be single threaded, but since the OS consists of many of them, it doesn't run on one core as such.

The driver model discussed there could very well be single threaded (Hammer?) and certainly having a multicore processor will help with that, provided there is enough memory bandwidth available and expensive forms of synchronisation are not needed. However, this is not the same as having the OS on one core and a game in another. It's possible to do that manually, just set the affinity in Task Manager, but I think that in many cases it's best to let the scheduler decide the load balance.

Edit: I'm not disagreeing with you on this at all, I just pointed out a technical detail, that most of the time both the game and the OS will be scheduled between both CPUs, ie. a single game thread might jump between CPUs.

Last edited by Zardoz on 23-Sep-2009 at 09:47 PM.

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@MikeB

Quote:

MikeB wrote: @Zardoz Quote: A single core is never ever ever dedicated to anything on Windows, sorry. The advantages in Windows of having multi-core improved over time. Multi-threading is needed for that. For the OS itself to take well advantage of multi-cores vs performance in a single core environment must include multi-processing abilities for core processes. A related quote from a few years ago: "Finally, keep in mind that the Windows XP driver model for Direct3D is quite inefficient, to such an extent that in many applications, the OS and driver overhead associated with issuing Direct3D calls approaches 50% of available CPU cycles.Hiding this overhead will be one of the major immediate uses of multi-core." http://www.anandtech.com/cpuchipsets/showdoc.aspx?i=2377&p=3 This may also help with regard to what I am pointing at: Why's my single core processor faster than my dual core? http://answers.yahoo.com/question/index?qid=20070918204048AAy2WtW (edit, wrong link)

The visual display update interface of Windows was moved to the gpu with Vista. Win7 in particular is quite nice. All "windows" display updates are handled by the gpu instead of soft-rendering on the cpu then copied to the gpu.

Regardless, this issue never affected games as they delt directly with the gpu (via directX) for display at all times.

@MikeB

Quote:

MikeB wrote: @Zardoz Quote: A single core is never ever ever dedicated to anything on Windows, sorry. The advantages in Windows of having multi-core improved over time. Multi-threading is needed for that. For the OS itself to take well advantage of multi-cores vs performance in a single core environment must include multi-processing abilities for core processes. A related quote from a few years ago: "Finally, keep in mind that the Windows XP driver model for Direct3D is quite inefficient, to such an extent that in many applications, the OS and driver overhead associated with issuing Direct3D calls approaches 50% of available CPU cycles.Hiding this overhead will be one of the major immediate uses of multi-core." http://www.anandtech.com/cpuchipsets/showdoc.aspx?i=2377&p=3

The context was 2005 era X86 CPU. Times has changed with the arrival Intel Core 2/ Core i7 and AMD Athlon II/Phenom II. Regardless of this issue, Crysis still blows away Uncharted 2 in graphics department.

Quote:

This may also help with regard to what I am pointing at: Why's my single core processor faster than my dual core? http://answers.yahoo.com/question/index?qid=20070918204048AAy2WtW (edit, wrong link)

Intel Core 2 Duo T7500 has auto-over clocking feature (refer to Intel Dynamic Acceleration) during single CPU core usage.

Last edited by Hammer on 24-Sep-2009 at 01:40 PM.

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