From mboxrd@z Thu Jan 1 00:00:00 1970 From: miller@hamnavoe.demon.co.uk To: 9fans@cse.psu.edu Date: Mon, 10 Jul 2000 17:21:41 +0100 Subject: Re: [9fans] Kernel question: i386 test-and-set problem Message-Id: Topicbox-Message-UUID: d6b7f546-eac8-11e9-9e20-41e7f4b1d025 Russ Cox writes: > ... Since we don't > play funny games with lock-free data structures, ... A notable exception is the funny game which sleep() and wakeup() play with the Rendez structure, which no longer has the lock which protected it in the original 2nd edition kernel. This game is not just funny but dangerous, as evidenced by the new coherence() calls introduced to counteract the resulting vulnerability to weakly coherent memory on some multiprocessors, and the long explanatory comment. Kids, don't try this at home ... practise the discipline of Safe Sharing (always use a lock) and you won't need to worry about memory coherence. -- Richard Miller