Analyze Linux Kernel I/O
- I/O Wait— this system-wide metric represents the amount of time during which the CPU cores were idle due to threads being in an I/O wait state.
- I/O Queue Depth— this metric shows the number of I/O requests submitted to the storage device. If the number of requests in a queue is zero, this means that there are no requests scheduled, and the disk is not utilized at all.
- I/O Data Transfer— this metric shows the number of bytes read from or written to the storage device(s).
- Page Faults— this metric shows the number of page faults that have occurred on the system. It is particularly useful when analyzing access to memory-mapped files.
- CPU Activity— this metric represents the portion of time the system spent in one of the following states:
- Idlestate — the CPU core is idle
- Activestate — the CPU core is executing a thread
- I/O Wait— the CPU core is idle, but there is a thread that could potentially be executed on this core that is blocked by disk access.
Analyze I/O Wait Time
Analyze Slow I/O Requests
- Regardless of the number of threads blocked on storage access, all CPU cores are actively executing application code.
- No threads are blocked on storage access.