How big an effect on compile times does L2 cache size have?

Question

I am in the middle of the decision process for a new developer workstation, and one remaining question is which processor to choose, and one of the early decisions is whether to go with Xeon or Core2 processors. (We've already restricted ourselves to HP machines, so we're only looking at Intel processors.)

The main goal of the upgrade is to shorten compile times as much as we can. We're using Visual Studio 2008 targeting .NET 3.5, mostly working on a solution with about a dozen projects. We know our build is CPU-bound. Since Visual Studio can't parallelize C# builds, we know we want to maximize CPU clock frequency - but the question is, do the larger caches of the Xeon line help during compilation, and if they do is the increase justifiable given the tripling in price?

Answer 1

You can add custom task to VS2008 in order for it to make build in parallel so the more processors (virtual) you have - the better. Take a look here. It helped me greatly.

Answer 2

I would really recommend that you measure this yourself. You're going to have loads of factors affecting performance e.g. are you compiling lots of small components, or one big deliverable (i.e. how CPU-bound will this be) ? And what disks are you specifying ? Memory ? All of this will make a difference, and it would be worth it to borrow some sample machines and test out your scenarios.

As for the question about cache size performance being 'worth it' - again - how much are you prepared to spend on compilation servers and how much is your time worth ? I suspect that if the servers are compiling more than a few hours a day and you have more than a couple of developers, the extra horsepower will more than pay for itself.

Answer 3

I would guess that the compile process is more I/O-bound than CPU-bound. At least I could cut my compile time in half by putting my ASP.NET application on a RAM drive. (See here). As such, I would suggest not only thinking about the CPU but also about your disks, perhaps even more so.

Answer 4

If I was you I would just go for the Q9550 with 12MB L2 cache :) They are currently good value for money.

I 'unfortunately' had to get a Core i7 860 due to my previous motherboard not supporting the FSB of the quadcore. I have no complaints though :)