NVMe is now faster than tmpfs in Linux
This is very counter-intuitive!
RAM disks are -slow- compared to a single high performance NVMe SSD [...]
The problem is that RAM disks always do synchronous IO and they consume CPU time copying the data to/from the RAM disk to/from user buffers. Hence you can only have one IO per CPU in flight at a time, instead of a few thousand IOs in flight per CPU when using asynchronous IO on spread across many NVMe SSDs.
IOWs, never use ram disks for performance testing XFS filesystems - the results never reflect real world performance on actual storage hardware.
(via @nsheridan)
Tags: via:nsheridan linux filesystems performance nvme tmpfs ssd