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The former - fsyncs are more expensive because they involve copy on write updates all the way up the tree to the root. Some of the fsyncs are there because of
by rogerbinns 14y ago
The former - fsyncs are more expensive because they involve copy on write updates all the way up the tree to the root. Some of the fsyncs are there because of ext4 quirks. That all said, every kernel release brings big improvements in btrfs especially metadata handling. IOW it is currently the worst it will be.
- jeffdavis 14y agoWhy not just sync the data change and sync the metadata changes only to a write-ahead log? Or if the data is logged also, you only need to sync the log. I assume btrfs uses a log, right?
- rogerbinns 14y agoA tree is the main data structure. The inspiration is this pdf http://www.usenix.org/events/lsf07/tech/rodeh.pdf http://www.usenix.org/events/lsf07/tech/rodeh.pdf There is a log to help with fsyncs. http://en.wikipedia.org/wiki/Btrfs http://en.wikipedia.org/wiki/Btrfs