Re: ufsstat - testers / feedback wanted!

From: Eric Anderson <anderson_at_centtech.com>
Date: Fri, 14 Oct 2005 12:40:49 -0500
Brian Candler wrote:
> On Fri, Oct 14, 2005 at 11:20:02AM -0500, Eric Anderson wrote:
> 
>>For statistics gathering purposes though, should I worry about this, or 
>>go for 'fast and imperfect' instead of 'perfect and slow'?  With 
>>filesystems, I think it's more important to leave performance high and 
>>get a notion of the statistics, rather than impact performance for 
>>perfect stats (that you may only look at occasionally anyhow).
> 
> 
> Losing the odd count probably isn't a problem, but I think there's the
> possibility of a badly wrong value if you're updating a 64-bit word in two
> halves. For example, it might be possible to wrap around from
> 00000000ffffffff to 0000000000000000 instead of 0000000100000000.

I suppose one could argue that this problem is no worse than using 32bit 
integers, except it would be right more often than not.  (right?)

Eric


-- 
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Eric Anderson        Sr. Systems Administrator        Centaur Technology
Anything that works is better than anything that doesn't.
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Received on Fri Oct 14 2005 - 15:41:18 UTC

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