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Date:	Thu, 08 Dec 2011 08:14:48 -0500
From:	Ryan Johnson <ryan DOT johnson AT cs DOT utoronto DOT ca>
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Subject:	Re: Machine very sluggish while compiling
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On 08/12/2011 6:18 AM, Robert Miles wrote:
> On 12/4/2011 4:06 AM, Corinna Vinschen wrote:
>> Anyway, stoppping the PCA service and setting its start mode to "Manual"
>> does the trick for me.  While I was at it I also disabled Superfetch,
>> which drops the memory usage of this svchost to a fraction of what it
>> used before, and the CPU usage to 0%, and I don't see any performance
>> difference.
> Are you aware that the Superfetch service deliberately tries to use 
> most of the
> memory not otherwise in use as a cache for the most frequently 
> accessed disk
> files, in order to speed up accesses to those files?  I've found it 
> rather slow to
> release this cache memory when some other program needs it, though.
In my experience Superfetch does a phenomenally bad job of predicting 
which files I (or my wife) actually plan to use. The machine is sluggish 
not (just) because the memory is uselessly tied up, but because the disk 
is constantly busy fetching data that will never be used and penalizes 
access to the data I actually do need. The memory wastage just compounds 
the problem by contributing additional swapping on top of all this other 
extra disk activity.

Both computers at my house saw *significant increases* in performance 
and responsiveness when I disabled Superfetch a few months ago.

Ryan


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