In the end I think Charles-Francois is right -- the rounding up in selectmodule.c (for epoll) and selectors.py (for poll and, redundantly[*], for epoll) should be sufficient to avoid the busy-wait behavior with delays under 1ms.

We're not promising real-time guarantees at any level, so both returning too early and too late must be acceptable. If a test fails frequently despite relaxed constraints, that's a problem with the test.

So I think Victor should apply his first patch (remove_granularity.patch) to both CPython and Tulip and then we can adjust any tests that still cause occasional red buildbots.

[*] It's not redundant when using Tulip on Python 3.3, so I prefer to keep it.