Write caching on FreeBSD
jdy at jdyson.com
jdy at jdyson.com
Wed Jan 26 19:00:27 PST 2005
Quick comment:
When doing/updating the write code, I carefully
limited the amount of pending write data so that
the system wouldn't 'go to sleep' while trying
to sync out massive amounts of data. For convienience,
this amount of write space was limited by the disk
cache buffer representation. My original disk cache
code wasn't limited to the cache buffers, and would
actually create large numbers of dirty pages. This
allowed for faster performance, except under load.
I was interested in the high load performance conditions,
and some mods have apparently been made to support
more pending writes (by increasing the disk buffer
cache representations?) Anyway, it seems like FreeBSD
currently has a good compromise (better than my original,
but also better than a no-holds barred scheme that
creates lots of dirty pages.)
John
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