Messages in this thread Patch in this message | | | Date | Sun, 23 Mar 2008 21:06:30 +0100 | From | Marcin Slusarz <> | Subject | [PATCH] documentation: nmi_watchdog=2 works on x86_64 (was: 2.6.25-rc: complete lockup on boot/start of X (bisected)) |
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On Sun, Mar 23, 2008 at 08:06:08PM +0100, Peter Zijlstra wrote: > On Sun, 2008-03-23 at 19:46 +0100, Marcin Slusarz wrote: > > > 4 different lockups: > > http://alan.umcs.lublin.pl/~mslusarz/kernel/2008.03.23-lockup/ > > Brilliant, these are extremely helpful. > > What seems to happen is a classic xtime deadlock, doing a xtime > seq_readlock while holding a seq_writelock. > > Only need to figure out _why_ that is happening.... > > > Are there any downsides of using nmi_watchdog=2 all the time? > > Some machines are said to not boot due to NMIs, hence the default is > off, but afaik, _if_ it works there are no downsides aside from the > slight NMI handling overhead. > > > ps: Documentation/nmi_watchdog.txt says: "Currently, local APIC mode > > (nmi_watchdog=2) does not work on x86-64.". It's not true, so maybe someone > > should update this file? > > Care to send a patch to the x86 maintainers? :-) >
--- documentation: nmi_watchdog=2 works on x86_64
Signed-off-by: Marcin Slusarz <marcin.slusarz@gmail.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> --- Documentation/nmi_watchdog.txt | 3 +-- 1 files changed, 1 insertions(+), 2 deletions(-)
diff --git a/Documentation/nmi_watchdog.txt b/Documentation/nmi_watchdog.txt index c025a45..757c729 100644 --- a/Documentation/nmi_watchdog.txt +++ b/Documentation/nmi_watchdog.txt @@ -23,8 +23,7 @@ kernel debugging options, such as Kernel Stack Meter or Kernel Tracer, may implicitly disable the NMI watchdog.] For x86-64, the needed APIC is always compiled in, and the NMI watchdog is -always enabled with I/O-APIC mode (nmi_watchdog=1). Currently, local APIC -mode (nmi_watchdog=2) does not work on x86-64. +always enabled with I/O-APIC mode (nmi_watchdog=1). Using local APIC (nmi_watchdog=2) needs the first performance register, so you can't use it for other purposes (such as high precision performance -- 1.5.3.7
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