Should I choose to take advantage of 64-bit?

Visual Studio: Why is there no 64 bit version?

Rico Mariani's Performance Tidbits — Thu, 11 Jun 2009 06:34:48 GMT

From time to time customers or partners ask me about our plans to create a 64 bit version of Visual Studio.

When to Move to 64-bit

Patrick Altman — Thu, 20 Jul 2006 07:36:44 GMT

Josh Williams offers a few tips on when to move to 64-bit from 32-bit.&nbsp; &nbsp; It is interesting...

re: Should I choose to take advantage of 64-bit?

joshwil — Wed, 19 Jul 2006 18:22:52 GMT

Loic -- I get the point. I'm suggesting that I believe it is not as benefitcial as many people think it is. If more registers is all you need then IA64 would be running away with the crown hands down. Most of the time for most of the scenarios I see (note the wiggle words there) stuff is not processor bound in tight loops. If it always was then more registers would make a bigger difference.

Jeroen -- In general we believe that managed code performance on 64-bit is competitive with 32-bit, in some cases better, in some cases worse, in most cases somewhere in the noise. However, the 64-bit CLR/JIT is in effect a v1 product competing against the 32-bit version which is for many practical purposes ~v3. We still however have some rough edges. If you can shoot me a relatively simple to execute repro for the problem you mention I can profile it and see where we're losing time (with a difference that large I would hope that something would jump out) and hopefully we can fix the problem in an upcoming release of the CLR.

re: Should I choose to take advantage of 64-bit?

Jeroen Frijters — Wed, 19 Jul 2006 11:35:03 GMT

What about managed code? I must say that I'm a little disappointed by the x64 managed code performance. Running ikvmc to build IKVM.GNU.Classpath.dll is much slower in 64 bit mode. 164 seconds of user mode CPU time vs. 63 seconds in 32 bit mode (by forcing the CLR to run in 32 bit mode -- so all other conditions are identical).

re: Should I choose to take advantage of 64-bit?

Loïc Minier — Wed, 19 Jul 2006 11:18:36 GMT

Well, I agree with Dean, you completely miss the point of x86/64, it *doubles* the amount of general purpose registers.

It's a known fact that one of the big problem with x86 is the small number of general registers, and this is how lower frequency arches can achieve a comparable amount of performance.

Beside, these many registers also balance your argument with respect to cache size. Code size is in some cases smaller due to the use of regs instead of the stack. This also lowers the amount of data to fetch from memory when more data is passed via registers.

However, it's nice that you balance your conclusion depending on the application type, and you're correct that some applications are negatively hit by the use of 64-bits pointers.

re: Should I choose to take advantage of 64-bit?

joshwil — Wed, 19 Jul 2006 04:59:23 GMT

Dean -- Certainly a good point and in medium sized tight loops those extra registers can be helpful. However often they don't make as much of a difference as people would like to believe, certainly in many cases they are an extra few % and in a couple particular cases they make all the difference. In my mind they aren't a big enough deal to make the list.

re: Should I choose to take advantage of 64-bit?

Dean Harding — Wed, 19 Jul 2006 03:52:07 GMT

What about the fact that 64-bit has more general-purpose registers? That should be in the "pluses" section as well, and should help with programs that would not otherwise normally see any benefits.

re: Should I choose to take advantage of 64-bit?

rickbrew — Wed, 19 Jul 2006 01:58:04 GMT

The only driver trouble I had on x64 was with my new HP printer. Other than that, it runs and performs like a dream.

re: Should I choose to take advantage of 64-bit?

joshwil — Wed, 19 Jul 2006 01:34:57 GMT

Gabriel -- it is true that for a lot of early adopters the driver support isn't quite there yet. However things are getting better for Vista. I've been using 64-bit for my primary machines for a few years and things are definitely better now.

However, the point of this entry isn't why to switch to 64-bit on your machine so much as why to target 64-bit with your development...

re: Should I choose to take advantage of 64-bit?

Gabriel Lozano-Morán — Wed, 19 Jul 2006 00:58:04 GMT

64-bit => Sh!t driver support that's the reason I had to go back from 64-bit Windows to the 32-bit equivalents. Maybe this is not entirely through if you by a standard Dell or another brand computer but it sure as hell is if you built your own computer.