From mboxrd@z Thu Jan 1 00:00:00 1970 From: Keith Owens Date: Fri, 07 Mar 2003 13:57:04 +0000 Subject: [Linux-ia64] ia64_spinlock_contention and NEW_LOCK Message-Id: List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-ia64@vger.kernel.org 2.4.0-test6-ia64-000811 introduced ia64_spinlock_contention and NEW_LOCK. AFAICT they have been disabled ever since they were introduced. Are there any plans to use this NEW_LOCK code? I have two reasons for asking. (1) If ia64_spinlock_contention is going to be used then it needs unwind data, otherwise an interrupt in this code will not get a decent backtrace. (2) To enable kdb and lkcd diagnosis of hung spinlocks, I want the contention path to check for a 'enter debugger now!' flag[*]. Obviously such a test would be better handled in a single contention routine instead of being expanded as part of every spinlock usage. [*] I tried DavidM's suggestion of using INIT interrupts to break into disabled spinlocks. It works, and with kdb v4.0 you get a decent backtrace. However INIT is far too destructive, once INIT has been sent the cpu is dead. Barely acceptable for a completely hung machine, no good if you are just trying to diagnose a problem.