Re: Next round: revised futex(2) man page for review
From: Peter Zijlstra <hidden>
Date: 2015-07-28 20:45:57
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linux-api, lkml
On Tue, Jul 28, 2015 at 10:23:51PM +0200, Thomas Gleixner wrote:
quoted
FUTEX_WAKE (since Linux 2.6.0) This operation wakes at most val of the waiters that are waiting (e.g., inside FUTEX_WAIT) on the futex word at the address uaddr. Most commonly, val is specified as either 1 (wake up a single waiter) or INT_MAX (wake up all wait‐ ers). No guarantee is provided about which waiters are awoken (e.g., a waiter with a higher scheduling priority is not guaranteed to be awoken in preference to a waiter with a lower priority).That's only correct up to Linux 2.6.21. Since 2.6.22 we have a priority ordered wakeup. For SCHED_OTHER threads this takes the nice level into account. Threads with the same priority are woken in FIFO order.
Maybe don't mention the effects of SCHED_OTHER, order by nice value is 'wrong'. Also, this code seems to use plist, which means it won't do the right thing for SCHED_DEADLINE either. Do we want to go fix that? -- To unsubscribe from this list: send the line "unsubscribe linux-man" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html