[tahoe-dev] [tahoe-lafs] #227: our automated memory measurements might be measuring the wrong thing

[tahoe-lafs]

#227: our automated memory measurements might be measuring the wrong thing
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 Reporter:  zooko               |           Owner:  zooko     
     Type:  defect              |          Status:  assigned  
 Priority:  major               |       Milestone:  eventually
Component:  dev-infrastructure  |         Version:  0.7.0     
 Keywords:                      |   Launchpad_bug:            
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Comment(by zooko):

 By the way, I don't think I succeeded at boiling down the results of my
 research for the consumption of others.  Here's the boiled-down version:
 measuring the vsize as we do in [wiki: our Performance page] gives a
 number much higher than what we actually want to know, and it changes even
 when the thing that we care about hasn't changed, so it is either useless
 or only barely useful.  Measuring the resident set size would give
 something probably smaller or possibly larger than the thing we want to
 know, and it too would change randomly when the thing we care about hasn't
 changed.  The two of them put together and then eyeballed might give you
 insight, or might just mislead you.

 The idea that I had and wrote up in this ticket (above) was a third
 option: turn off swap and measure resident.  That gives you a number that
 is probably pretty close to what you care about, if what you care about is
 something like "How much RAM do I need in my machine to run one Tahoe node
 without it needing to swap.".  (If you have a different idea of what you
 want to know then by all means speak up.)

 Anyway, that's all my attempt to restate the history of this ticket and
 explain why you shouldn't pay much if any attention to the numbers on
 [wiki:Performance the Performance page].  The new news is that Matt
 Mackall has been working on this problem and has a new tool that can help
 (on Linux):

 http://lwn.net/SubscriberLink/329458/d28c2d45a663045a

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Ticket URL: <http://allmydata.org/trac/tahoe/ticket/227#comment:6>
tahoe-lafs <http://allmydata.org>
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