The buffer cache can now occupy as much free memory
as is available, up to the system limit of 3.75 GB.
Prior to 10.10, the implementation of the
buffer cache silently limited the size to 1 GB.
The kernel parameters dbc_min_pct or
bufpages can be set beyond 1 GB if
that physical memory is available.
This change allows the storage of nearly 3.75 GB
of file data in memory. This should produce a noticeable
increase of
speed for applications that access between 1 and
3.75 GB of file system data. There is one exception: NFS
server code is unable to take advantage of a buffer
cache over 1 GB due to limitations in the
networking drivers.
If the kernel configuration requested, but previously
did not receive, a buffer cache larger than 1 GB,
the increase in size at 10.10 might change
performance and response time, depending on the workload.
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