[Pvfs2-developers] handle ledger

Pete Wyckoff pw at osc.edu
Tue Jan 29 17:41:20 EST 2008


slang at mcs.anl.gov wrote on Tue, 29 Jan 2008 15:53 -0600:
> On Jan 29, 2008, at 1:42 PM, Pete Wyckoff wrote:
>> Yeah.  It will just run through the same set of allocated handles,
>> taking a long time that first time for people with lousy RNGs.  Then
>> it will fall into an unallocated space and continue normally.  As
>> long as there is a configure test for random_r, we can fall back to
>> lrand48() and friends or even ancient srand/rand.  /dev/urandom
>> test must be at runtime, with graceful fallback to a seed made up of
>> hostname[0:255] | time() << 29 | coll_id << 63 | ... any other
>> random stuff you can get your hands on in that routine easily.
>
> Not sure hostname is actually useful in this case, since the handles are 
> allocated (and only need to be unique) per-server.  Same with the fs_id.  I 
> could use process id I suppose...
>
> Can I check for /dev/urandom with a runtime check in configure, or are 
> those verboten for cross-compiles?

Verboten unfortunately.  Just cause it works on the linux front-end
doesn't mean it will work on the catamount/bg/whatever odd back end.
Although I think people only ever run servers on real machines these
days.  But catching open() return values is pretty easy.

		-- Pete


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