[peterwwillis]

The kernel has a clear definition of what will be backwards compatible, and what never will be. In-kernel interfaces are never stable, and kernel-to-userspace interfaces are very stable, with an ABI docs directory breaking out what is and isn't.

https://github.com/torvalds/linux/blob/e7aa8c2eb11ba69b1b690...

If the kernel's user interface just started blocking on open for 4000 milliseconds for no apparent reason, people would not be happy. Firefox expects users to demand that app writers edit, recompile, test, and ship them a new app to prevent the block. This is <insert lots of not very nice adjectives>.

[zlynx]

This is an interesting example because the kernel's open() interface blocks for 4,000 ms all the time. Heavy swapping or the ext3 journal is full and some other app just called fsync().

Apps have to handle it. If they don't, because for example, they access the disk while also trying to be a display compositor, then they are simply broken. It does not matter if the kernel is usually fast enough. Because sometimes it isn't.