On RHEL4, RAC 10g+OCFS2 and filesystemio_options=setall, I've checked
that physical reads still increase the "cached" column of "free"
output, i.e. reading 1GB of data results in 1GB for the "cached"
Since it is of concern for such direct I/O, I've asked the Oracle
support about that and their tentative explanation is that the shared
memory (SGA) is included in this "cached" value on RHEL4.
Any thought about that?
FYI this 32-bit system is not configured with HugePages nor ramfs or
shmfs for the SGA. It is a "standard" RHEL4 installation regarding