Messages in this thread | | | Date | Wed, 7 May 2014 21:28:14 -0400 | From | Don Zickus <> | Subject | Re: [PATCH 5/5] x86, nmi: Add better NMI stats to /proc/interrupts and show handlers |
| |
On Wed, May 07, 2014 at 07:50:48PM +0000, Elliott, Robert (Server Storage) wrote: > Don Zickus <dzickus@redhat.com> wrote: > > The main reason for this patch is because I have a hard time knowing > > what NMI handlers are registered on the system when debugging NMI issues. > > > > This info is provided in /proc/interrupts for interrupt handlers, so I > > added support for NMI stuff too. As a bonus it provides stat breakdowns > > much like the interrupts. > > /proc/interrupts only shows online CPUs, while /proc/softirqs shows > all possible CPUs. Is there any value in this information for all > possible CPUs? Perhaps a /proc/hardirqs could be created alongside.
Well if they are not online, they probably won't be generating NMIs, so I am not sure there is much value there.
> > > The only ugly issue is how to label NMI subtypes using only 3 letters > > and still make it obvious it is part of the NMI. Adding a /proc/nmi > > seemed overkill, so I choose to indent things by one space. > > The list only shows the currently registered handlers, which may > differ from the ones that were registered when the NMIs whose counts > are being displayed occurred. You might want to describe these new > rows and mention that in Documentation/filesystems/proc.txt and > the proc(5) manpage.
Ok, but that is a /proc/interrupts problem not one specific to NMI, no?
> > > Sample output is below: > > > > [root@dhcp71-248 ~]# cat /proc/interrupts > > CPU0 CPU1 CPU2 CPU3 > > 0: 29 0 0 0 IR-IO-APIC-edge timer > > <snip> > > NMI: 20 774 10986 4227 Non-maskable interrupts > > LOC: 21 775 10987 4228 Local PMI, arch_bt > > EXT: 0 0 0 0 External plat > > UNK: 0 0 0 0 Unknown > > SWA: 0 0 0 0 Swallowed > > Adding the list of NMI handlers in /proc/interrupts is a bit > inconsistent with the other interrupts, which don't describe their > handlers. It would be helpful to distinguish between a handler > list being present, being present but empty, or not being present. > > Maybe use parenthesis like this (using Ingo's suggested format): > NMI: 20 774 10986 4227 Non-maskable interrupts > NLC: 21 775 10987 4228 NMI: Local (PMI, arch_bt) > NXT: 0 0 0 0 NMI: External (plat) > NUN: 0 0 0 0 NMI: Unknown () > NSW: 0 0 0 0 NMI: Swallowed > LOC: 30374 24749 20795 15095 Local timer interrupts >
Hmm, looking at /proc/interrupts I see
1: 858014 29054 23191 9337 IO-APIC-edge i8042 8: 3 24 10 2 IO-APIC-edge rtc0 9: 387555 9219 8308 7944 IO-APIC-fasteoi acpi 12: 9251360 163811 158846 141916 IO-APIC-edge i8042 16: 0 0 0 0 IO-APIC-fasteoi mmc0 17: 14 5 7 10 IO-APIC-fasteoi 19: 6892 367 13 10 IO-APIC-fasteoi ehci_hcd:usb2, ips, firewire_ohci 23: 1363281 753 94 94 IO-APIC-fasteoi ehci_hcd:usb1
Those may not be specific handlers, but they are registered irq names, no? That basically matches what I was trying to accomplish with NMI.
I guess I don't see how what I did is much different than what already exists.
> > diff --git a/arch/x86/kernel/irq.c b/arch/x86/kernel/irq.c > > index d99f31d..520359c 100644 > > --- a/arch/x86/kernel/irq.c > > +++ b/arch/x86/kernel/irq.c > ... > > +void nmi_show_interrupts(struct seq_file *p, int prec) > > +{ > > + int j; > > + int indent = prec + 1; > > + > > +#define get_nmi_stats(j) (&per_cpu(nmi_stats, j)) > > + > > + seq_printf(p, "%*s: ", indent, "LOC"); > > + for_each_online_cpu(j) > > + seq_printf(p, "%10u ", get_nmi_stats(j)->normal); > > + seq_printf(p, " %-8s", "Local"); > > + > > + print_nmi_action_name(p, NMI_LOCAL); > > + > > + seq_printf(p, "%*s: ", indent, "EXT"); > > + for_each_online_cpu(j) > > + seq_printf(p, "%10u ", get_nmi_stats(j)->external); > > + seq_printf(p, " %-8s", "External"); > > + > > + print_nmi_action_name(p, NMI_EXT); > > + > > + seq_printf(p, "%*s: ", indent, "UNK"); > > + for_each_online_cpu(j) > > + seq_printf(p, "%10u ", get_nmi_stats(j)->unknown); > > + seq_printf(p, " %-8s", "Unknown"); > > + > > + print_nmi_action_name(p, NMI_UNKNOWN); > > + > > The NMI handler types are in arch/c86/include/asm/nmi.h: > enum { > NMI_LOCAL=0, > NMI_UNKNOWN, > NMI_SERR, > NMI_IO_CHECK, > NMI_MAX > }; > > The new code only prints the registered handlers for NMI_LOCAL, > NMI_UNKNOWN, and the new NMI_EXT. Consider adding counters > for NMI_SERR and NMI_IO_CHECK and printing their handlers too. > > drivers/watchdog/hpwdt.c is the only code currently in > the kernel registering handlers for them.
Yeah, I guess I was trying to remove NMI_SERR and NMI_IO_CHECK. I forgot if I accomplished that with this patch set or not. Instead I had hpwdt do the ioport read directly instead of having do_default_nmi do it. I can look at it again.
Cheers, Don
| |