APM and low latency profiles

[dogtopus]

Currently even latency- or performance-oriented profiles don't seem to disable APM/sleep timeout for HDDs only (irrelevant for SSDs for obvious reasons), which could cause huge latency spikes when accessing data from them after some period of inactivity.

[yarda]

Thanks, this seems like a good proposal. It maybe critical on rotary disks but it shouldn't cause problems with SSDs, that's probably why we haven't received such report sooner.