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From Justin Swanhart <greenl...@gmail.com>
Subject Re: What is the best file system for Lucene?
Date Tue, 30 Nov 2004 13:02:48 GMT
On Tue, 30 Nov 2004 12:07:46 -0000, Pete Lewis <pete@uptima.co.uk> wrote:
> Also, unless you take your hyperthreading off, with just one index you are
> searching with just one half of the CPU - so your desktop is actually using
> a 1.5GHz CPU for the search.  So, taking account of this its not too
> surprising that they are searching at comparable speeds.....
> 
> HTH
> Pete

Actually, that isn't how hyperthreading works.  The "second" CPU in a
hyperthreaded system should only run threads when the "main" cpu is
waiting on another task, like a memory access.  The second, or sub CPU
is only a virtual processor.  There aren't really two chips on board. 
New multicore processors will actually have more than one processor 
in one chip.

Problems can arise when you are using a HT processor on an operating
system that doesn't know about HT technology.  The OS should only
schedule jobs to run on the sub CPU under very specific circumstances.
 This is one of the major reasons for the scheduler overhaul in Linux
2.6.  The default scheduler in 2.4 would assign threads to the sub CPU
that shouldn't have been, and those threads would suffer from resource
starvation.

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