[ZODB-Dev] Re: BerkeleyDB's page cache

[Chris Withers]

Toby Dickenson wrote:
> 
> If we exclude packing, my evidence is the opposite of the that.
> BerkeleyStorage/Full had a flat memory usage profile during normal
> use, which is what I expect from looking at the code.

Hmmm... maybe it was Linux VMM management being unhelpful :-S

> Chris, did you add a set_cachesize line in your DB_CONFIG file? That
> controls the size of BerkeleyDB's internal cache. Running with the
> default of 256k could well cause thashing in that cache. 

Yeah, I think I jumped that up to 256Mb, it was certainly something large...

> If you still
> have your database environment around, "db_stat -m" will tell you
> "number of pages found in cache". The number is application-dependant
> (as always) but I guess anything below 95% is a sign of trouble.

Again, IIRC, it was higher than that, sadly, I don't have the environment around
right now...

cheers,

Chris