On 29.8.2014 16:12, Tom Lane wrote: > Jeff Davis <pg...@j-davis.com> writes: >> I have a new approach to the patch which is to call a callback at each >> block allocation and child contexts inherit the callback from their >> parents. The callback could be defined to simply dereference and >> increment its argument, which would mean block allocations anywhere in >> the hierarchy are incrementing the same variable, avoiding the need to >> traverse the hierarchy. > > Cute, but it's impossible to believe that a function call isn't going > to be *even more* overhead than what you've got now. This could only > measure out as a win when the feature is going unused. > > What about removing the callback per se and just keeping the argument, > as it were. That is, a MemoryContext has a field of type "size_t *" > that is normally NULL, but if set to non-NULL, then we increment the > pointed-to value for pallocs and decrement for pfrees.
How is that going to work with two memory contexts (parent/child), both requesting accounting? If I understand the proposal correctly, the child will either inherit pointer to the field in parent (and then won't get accounting for it's own memory), or wil get a private field (and thus won't update the accounting of the parent context). Or am I missing something? regards Tomas -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
