Joseph Grace wrote:
Suresh:
Does Mac OS has concept of write cache enabling ? Numbers below are with write cache enabled/disabled ?
Yes, OSX has write cache enabling. Presumably it's on by default (though I admit to not knowing how to confirm that), so my numbers include it. That's why I ran the test under a variety of circumstances. Benchmarks are hard, and the numbers vary a lot, so I flagged the variance. I'm not sure what all the factors are, but I believe your (implied) suspicion that cache'ing is one such factor.
= Joe =
Yes, trying to find out the write cache factor in "rws"/"rwd" performance numbers. What I observerd is on Win2k i
when write cache is enabled "rws" mode does not seem to sync immediately to the disk unlike FileDescriptor.sync(); I think this
is ok because user has chosen the write cache enabling option. When write cache is disabled on windows the "rws" mode
write does seem to perform the sync.(Note: On JDK141 sycn does not happen this case also).
I don't have much knoweledge of jvm internals , but if the expected behaviour jvm on MAC OS is similar
to Windows, write performance numbers in "rws/rwd" mode won't be accurate when write cache is enabled.
I also don't know how to disable the write cache on Mac. Can't really say "rws" does not sync for sure on Mac
unless the write cache is disabled.
-suresht
