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From: | Phil Holmes |
Subject: | Re: make doc problem |
Date: | Sun, 22 Jan 2012 20:13:13 -0000 |
On 22/01/2012 2:38 PM, David Kastrup wrote:Julien Rioux<address@hidden> writes:I can't run -j, I have a single core.This is factually incorrect. You can run -j just fine, but you can't expect much of a speedup. On a single-core machine, make -j 2 typically gives you a speedup of maybe 15% (given sufficient memory) since the CPU can keep busy on processing a second job when the other job is waiting for the disk to provide new input. More importantly, you'll get to see the same kind of problems that the true multi-core people experience when using -j. So very much recommended for testing.Thanks, you're quite right CPU is not the limiting factor for the build. Disk access and usage of swap when compiling input/regression/collated-files slows down the build to a crawl for me.-- Julien
As a general rule, CPU is very much the limiting factor on make and make doc. With my "single cpu" virtual machine on my Windows box, the CPU is stuck at 100%. With my multi-core Ubuntu box, most of the time all 8 CPUs run 100%, with memory never over 1.5 Gigs. This is using a fairly large SSD, but I'm 99% certain that, all other things being equal, CPU is king when building lily.
-- Phil Holmes Bug Squad
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