3 ms·
How much overhead does it take to record disk latency data in realtime? Does it slow down the disks? I read on the guy's blog that ZFS's write caching meant tha
by sqs 18y ago
How much overhead does it take to record disk latency data in realtime? Does it slow down the disks? I read on the guy's blog that ZFS's write caching meant that end users didn't experience increased latency when the guy yelled at the disks, but surely there must be some performance cost to all this instrumentation.
- seiji 18y agoIt's possible thanks to the magic of dtrace. In a storage appliance, you wouldn't expect the load to be overwhelmingly CPU bound[1], so performing real time instrumentation isn't a noticeable performance hit: http://www.solarisinternals.com/wiki/index.php/DTrace_Topics_Overhead http://www.solarisinternals.com/wiki/index.php/DTrace_Topics... [1]: assuming you aren't using ZFS gzip compression: http://blogs.smugmug.com/don/2008/10/13/zfs-mysqlinnodb-compression-update/ http://blogs.smugmug.com/don/2008/10/13/zfs-mysqlinnodb-comp...