4 ms·
"My experience with it is that once a disk-backed machine (as opposed to SSD) has started swapping, it's essentially unusable" The OS should start swapping ver
by zzzcpan 10y ago
"My experience with it is that once a disk-backed machine (as opposed to SSD) has started swapping, it's essentially unusable"
The OS should start swapping very early to avoid bursts of disk I/O and rendering the system unusable. On linux this is somewhat configurable, even if not user friendly, but a combination of swappiness and vfs_cache_pressure could turn it into a usable machine, taking care of inefficient memory usage, memory leaks, unnecessary vfs cache, etc.
- scottlamb 10y ago> The OS should start swapping very early to avoid bursts of disk I/O and rendering the system unusable. I think you're talking about the I/O of paging dirty things out, but I'm talking about the fact that some memory location is no longer present in RAM, so accessing it will take 10 ms or more to page in. The system is not only useless while actively swapping. It's useless after it has ever swapped, and you can only recover by disabling swap ("sudo swapoff -a") or rebooting.