From: Keith Owens <kaos@sgi.com>
To: linux-ia64@vger.kernel.org
Subject: [Linux-ia64] ia64_spinlock_contention and NEW_LOCK
Date: Fri, 07 Mar 2003 13:57:04 +0000 [thread overview]
Message-ID: <marc-linux-ia64-105590709806001@msgid-missing> (raw)
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.
next reply other threads:[~2003-03-07 13:57 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-03-07 13:57 Keith Owens [this message]
2003-03-11 22:37 ` [Linux-ia64] ia64_spinlock_contention and NEW_LOCK David Mosberger
2003-03-12 1:38 ` Keith Owens
2003-03-12 1:59 ` David Mosberger
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