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| author | Mauro Carvalho Chehab <mchehab@s-opensource.com> | 2017-05-16 10:23:05 -0300 |
|---|---|---|
| committer | Jonathan Corbet <corbet@lwn.net> | 2017-07-14 13:57:59 -0600 |
| commit | 5da98b8230fb998b0731b2ba3893461ff238a297 (patch) | |
| tree | 3ed2748067826eecde3bec1e167f63277919132f /Documentation/pi-futex.txt | |
| parent | 5426a2cc70be499ea3bc67985c0608c7ac62fe6c (diff) | |
| download | linux-rpi3-5da98b8230fb998b0731b2ba3893461ff238a297.tar.gz linux-rpi3-5da98b8230fb998b0731b2ba3893461ff238a297.tar.bz2 linux-rpi3-5da98b8230fb998b0731b2ba3893461ff238a297.zip | |
pi-futex.txt: standardize document format
Each text file under Documentation follows a different
format. Some doesn't even have titles!
Change its representation to follow the adopted standard,
using ReST markups for it to be parseable by Sphinx.
This document requires just minor adjustments to match
the standard documentation style:
- promote document name;
- remove extra collons on some chapter titles;
- use "-" for a bulleted list.
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Diffstat (limited to 'Documentation/pi-futex.txt')
| -rw-r--r-- | Documentation/pi-futex.txt | 15 |
1 files changed, 8 insertions, 7 deletions
diff --git a/Documentation/pi-futex.txt b/Documentation/pi-futex.txt index 9a5bc8651c29..aafddbee7377 100644 --- a/Documentation/pi-futex.txt +++ b/Documentation/pi-futex.txt @@ -1,5 +1,6 @@ +====================== Lightweight PI-futexes ----------------------- +====================== We are calling them lightweight for 3 reasons: @@ -25,8 +26,8 @@ determinism and well-bound latencies. Even in the worst-case, PI will improve the statistical distribution of locking related application delays. -The longer reply: ------------------ +The longer reply +---------------- Firstly, sharing locks between multiple tasks is a common programming technique that often cannot be replaced with lockless algorithms. As we @@ -71,8 +72,8 @@ deterministic execution of the high-prio task: any medium-priority task could preempt the low-prio task while it holds the shared lock and executes the critical section, and could delay it indefinitely. -Implementation: ---------------- +Implementation +-------------- As mentioned before, the userspace fastpath of PI-enabled pthread mutexes involves no kernel work at all - they behave quite similarly to @@ -83,8 +84,8 @@ entering the kernel. To handle the slowpath, we have added two new futex ops: - FUTEX_LOCK_PI - FUTEX_UNLOCK_PI + - FUTEX_LOCK_PI + - FUTEX_UNLOCK_PI If the lock-acquire fastpath fails, [i.e. an atomic transition from 0 to TID fails], then FUTEX_LOCK_PI is called. The kernel does all the |