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I'm waiting for Excel to finish a recalculation and I notice that the CPU usage as reported by Task Manager occasionally spikes to 51% or 52% on a Pentium 4 with hyper-threading. How is a single-threaded application like Excel 2003 doing this?
Is it just a rounding/estimation error on the part of Task Manager? Or is it something to do with HT allocation i.e. I wouldn't see this happening on a genuine dual-core or dual-CPU machine?
Exactly, it's most likely from a repaint, or an input thread. Excel 2003 is not "multi-threaded" in its calculations, but that doesn't mean that the whole program run on a single thread, of course. – Gnoupi – 2010-03-25T16:50:30.173
1Rather than arguing about the inner workings of a closed-source program, why don't you just tell Task Manager to show you the "Threads" column? It lists the number of threads in an application... – marcusw – 2010-03-25T17:48:34.713
1I see that Excel has 5 threads, so this makes perfect sense. I made the assumption that because pre 2007 versions of Excel only have 1 calculation thread that the program only uses 1 thread, a bit silly in retrospect! :) – Lunatik – 2010-03-25T22:05:44.010
Also, the OS is multi-threaded. While Excel is running, it's telling the OS to do all kinds of things. The OS can do all kinds of things in its own threads such as pre-fetching files, flushing modified pages to disk, zeroing pages of memory that have been returned, redrawing the screen, and so on. – David Schwartz – 2012-01-14T02:18:54.297