4 ms·
He doesn't mean rebooting will take microseconds/nanoseconds, he means the transaction commit will take that long. Before, a transaction commit meant flushing
by martincmartin 8y ago
He doesn't mean rebooting will take microseconds/nanoseconds, he means the transaction commit will take that long. Before, a transaction commit meant flushing disk, at least as far as the disk controller. Now, commit = memory barrier.
- robotresearcher 8y ago"What that enables is powering down servers that aren't being used with the ability to power them up in milliseconds rather than seconds." (great-grandparent)
- ChuckMcM 8y agoActually and "restarting". Technically it isn't "booting" because the OS is already in memory and initialized, it just isn't running. Given your typical motherboard which you tell to bypass POST, it can go from power applied to memory controllers alive in just a few microseconds. The code then to go from there to running is also quite small, especially if there aren't things like graphics controllers on the PCI bus that have to be initialized first.
- namibj 8y agoAnd even those can probably be lazy-loaded, with a page fault in the IOMMU and handled as soon as the rest is done, or the rest isn't doing anything and something is thus blocking on the GPU initialisation.