Hi,
I create patch that can drop duplicate buffers in OS using usage_count
alogorithm. I have developed this patch since last summer. This feature seems to
be discussed in hot topic, so I submit it more faster than my schedule.
When usage_count is high in shared_buffers, they are hard to drop from
shared_buffers. However, these buffers wasn't required in file cache. Because
they aren't accessed by postgres(postgres access to shared_buffers).
So I create algorithm that dropping file cache which is high usage_count in
shared_buffers and is clean state in OS. If file cache are clean state in OS, and
executing posix_fadvice DONTNEED, it can only free in file cache without writing
physical disk. This algorithm will solve double-buffered situation problem and
can use memory more efficiently.
I am testing DBT-2 benchmark now...
Regards,
--
Mitsumasa KONDO
NTT Open Source Software Center