[154364] in North American Network Operators' Group
Re: F-ckin Leap Seconds, how do they work?
daemon@ATHENA.MIT.EDU (Bryan Horstmann-Allen)
Tue Jul 3 04:43:07 2012
Date: Tue, 3 Jul 2012 04:41:21 -0400
From: Bryan Horstmann-Allen <bdha@mirrorshades.net>
To: nanog@nanog.org
In-Reply-To: <20120703072714.GG2221@hezmatt.org>
Reply-To: bdha@mirrorshades.net
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
+------------------------------------------------------------------------------
| On 2012-07-03 17:27:14, Matthew Palmer wrote:
|
| The problems I saw were related to programs that use futex(2) (Java, MySQL,
| Chromium, in my personal experience) chewing up lots of CPU because the
| futex system call wasn't quite doing what it was supposed to be doing
| (waking up threads when they were OK to proceed) and instead constantly
| waking the threads up, having the threads go "OK, so my lock is clear and
| I'm ready to go?", the kernel saying "oh, no, sorry" and the thread going
| back to sleep again -- only to be woken up again immediately. Sort of an
| object lesson in why busy-wait locks suck.
A good dig into the problem, and previous problems with that code:
http://landslidecoding.blogspot.com/2012/07/linuxs-leap-second-deadlocks.html
Cheers.
--
bdha
cyberpunk is dead. long live cyberpunk.
