Messages in this thread | | | Date | Mon, 10 Feb 2014 08:45:16 -0800 | From | Dave Hansen <> | Subject | Re: [tip:perf/core] x86/nmi: Push duration printk() to irq context |
| |
On 02/10/2014 05:29 AM, tip-bot for Peter Zijlstra wrote: > x86/nmi: Push duration printk() to irq context > > Calling printk() from NMI context is bad (TM), so move it to IRQ > context.
Bad since the I/O device that we're doing it to may be slow and make the NMI painfully long?
I can see why it might be a bad idea, but I'm unsold that it is *universally* a bad idea.
> In doing so we slightly change (probably wreck) the debugfs > nmi_longest_ns thingy, in that it doesn't update to reflect the > longest, nor does writing to it reset the count.
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.
| |