vCPU & Excel Question

[Damo007]

I have an issue with a new RDS server I just built for a client and its MS excel processing power.

I just moved them from a physical RDS server with duel 4 core processors on to a virutal RDS server with two vCPU's. Performance is great so far and I only have around 20 users on there, 15 at one time typically.

I have one user, the CFO, who has some fancy excel spread sheets (excuse the lack of my excel knowledge for the correct term), which seem to do a lot of number cruncing in the background when he runs his formulas (linked spread sheets & a lot going on). It's a very time consuming process with him having to run this type of process on around 30 different excel files weekly. This used to take him around 40 seconds per document on the old server, and now takes about 1 minute 30 seconds per file. As you would expect from a CFO he's very organised, knows the time it used to take down to the second and has this down to a fine art. On the bottom of excel you can see it's using multiple processors to carry out the calculations and he knew the excel files used to show (down the bottom fo the spreadsheet) 8 processors working on the old server, and now he can only see 2 on my new server. This all makes complete sense.......

With overall performance being good on the server I don't want to just go throwing more CPU at the issue, since it is a single user (albeit a very important one), without posting here and just getting other peoples thoughts. Does anyone have any ideas? Maybe my only choice is to bump this up to 3 or 4 processors?

[JPM300]

There is two things you can try.  The first is obviously bump the vCPU temporarily and see if it increases the speed any.  The other is you can try and turn off hyper thredding and run the through the testing process again.  First with two vCPU's then with 4 vCPU's if you don't get to the performance numbers you want.

The reason for this is SOMETIMES on a RDS or Terminal Server hyper-threading can be an issue with heavy CPU processes.  The reason for this is hyper-threading splits a core into two but shares the same core/CPU cache.  So what happens sometimes is when one job fires off a heavy workload and consumes the cores cache the other hyper-threaded core has to wait to use the cache.  Now keep in mind this is pretty uncommon and you will usually see better gains with hyper-threading but I have seen it.

Aside from those things if adding more vCPU's is the only thing that speeds it up they may just have to add another host earlier down the the line then expected depending on what is going on in the cluster.  You could also try putting a higher share value on the CPU for that 1 VM and see if it helps any.  Putting a higher CPU share value will only help if there is CPU contention.

I hope this has helped.

[grace27]

Hi

Welcome to communities.

you may change priority of excel file high or check if any updated installed recently. .