From: Peter Zijlstra Date: Tue, 11 Feb 2014 15:01:16 +0000 (+0100) Subject: perf/x86: Warn to early_printk() in case irq_work is too slow X-Git-Tag: v3.15-rc1~181^2~24 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=cd578abb24aa67ce468c427d3356c08ea32cf768;p=pandora-kernel.git perf/x86: Warn to early_printk() in case irq_work is too slow On Mon, Feb 10, 2014 at 08:45:16AM -0800, Dave Hansen wrote: > The reason I coded this up was that NMIs were firing off so fast that > nothing else was getting a chance to run. With this patch, at least the > printk() would come out and I'd have some idea what was going on. It will start spewing to early_printk() (which is a lot nicer to use from NMI context too) when it fails to queue the IRQ-work because its already enqueued. It does have the false-positive for when two CPUs trigger the warn concurrently, but that should be rare and some extra clutter on the early printk shouldn't be a problem. Cc: hpa@zytor.com Cc: tglx@linutronix.de Cc: dzickus@redhat.com Cc: Dave Hansen Cc: mingo@kernel.org Fixes: 6a02ad66b2c4 ("perf/x86: Push the duration-logging printk() to IRQ context") Signed-off-by: Peter Zijlstra Link: http://lkml.kernel.org/r/20140211150116.GO27965@twins.programming.kicks-ass.net Signed-off-by: Thomas Gleixner --- Reading git-diff-tree failed