NMI Watchdog on Linux


Non-Maskable Interrupt(NMI) is the highest priority interrupt that can not be masked by any software. Basically, this is the scenario when you press CTRL+ALT+DELETE on Windows computer. NMI watchdog is available for i386 and amd64 architectures.In order to use the NMI watchdog, operating systems’ kernel must support APIC(Advanced Programmable Interrupt Controller) protocol.

NMI watchdog can be enabled by the kernel parameters;

kernel.nmi_watchdog=1 →(I/O APIC)
kernel.nmi_watchdog=2 → (Locall APIC)

When NMI is enabled , system will periodically generate a NMI call. Each NMI invokes a handler in Linux kernel and check the number of interrupts. If the NMIs’ handler detects the number of interrupts hasn’t changed for a certain period of time, it assumes that kernel is hung.Then it invokes a kernel panic.

Watchdog Timer

Command shows the interrupts per CPUs.

$ cat /proc/interrupts
       CPU0       CPU1       CPU2       CPU3             
NMI:    24         18         21         18  Non-maskable interrupts

NMI watchdog can be useful to detect server hung and reduce down time. But highly recommended to analyze system performance before enable NMI watchdog. NMI generates occasionally high number of interrupts and reduce server performance.

You can follow these steps to enable and disable NMI watchdog. I always recommend to enable NMI watchdog after performance analysis. Because sometimes it can be more complicated to detect kernel hung in order to analyze server performance.

Enable NMI:

kernel.nmi_watchdog=1 →(I/O APIC)
kernel.nmi_watchdog=2 → (Locall APIC)
sysctl -w kernel.nmi_watchdog=1

Disable NMI:

kernel.nmi_watchdog=0
sysctl -w kernel.nmi_watchdog=0

You can only run this command which kernel version is 2.6.18–238 and later. Otherwise you have to edit grub.conf then reboot server to disable NMI watchdog.

#vim /boot/grub/grub.conf
kernel /vmlinuz-2.6.18–194.el5 ro root=/dev/VolGroup00/LogVol00 nmi_watchdog=0
Output shows that  NMI watchdog is disabled. Because there is no interrupt on CPUs.
$ cat /proc/interrupts
       CPU0     CPU1    CPU2     CPU3             
NMI:    0        0        0        0   Non-maskable interrupts

Also it’s possible to send NMI request with IPMITOOL tool. You can check this link for more detail.

Tagged In:

I'm a IT Infrastructure and Operations Architect with extensive experience and administration skills and works for Turk Telekom. I provide hardware and software support for the IT Infrastructure and Operations tasks.

205 Total Posts
Follow Me

53 Comments

  1. They are re-invigorated and find themselves physically and emotionally re-charged. saleviabuy.com i am a woman and i took viagra

  2. generic form of viagra http://fmedrx.com/ canada online pharmacy generic viagra pictures of generic viagra

  3. legit viagra online http://usggrxmed.com/ does generic viagra work comprar viagra online

  4. viagra rapid tabs reviews getting viagra in turkey viagra w uk

  5. works as well as viagra viagra clone buying egypt viagra

  6. oxandrolona viagra buspar and viagra viagra soft brasil

  7. viagra gold paradiseviagira.com \'generic viagra\' 50 mg 30 pills

  8. viagra capsule online where can i buy female viagra in india female viagra singapore

  9. sildenafil prices brand viagra viagra tablets in india online

  10. taking viagra holiday https://buybuyviamen.com/ mhra fake viagra

  11. viagra europe online pharmacy prices for sildenafil where can i get real viagra

  12. viagra dopo pranzo liquid gel viagra what works just as good as viagra

  13. 20 mg sildenafil 680 viagra india price 100mg sildenafil no rx canadian

  14. guidelines to write a research paper write a wedding speech heading for a college essay

  15. critical thinking essays legal research proposal a good thesis statement for a research paper

  16. university of texas essays literature review for project essay writing reddit

  17. cheap assignments algebra and geometry ma dissertation

  18. writing help custom essay gonja tenten write my essay for me free

  19. writing a synopsis for a research paper research paper how to write online writing essay

  20. research paper note taking thesis statement for analytical essay writing argument essay

  21. generic viagra au ordering viagra through paypal viagra fro sale

  22. homework service leadership college essays format for writing a history research paper

  23. brand cialis on line cialis viagra cialis with dapoxetine without prescription mastercard

  24. buy viagra with paypal canada pharmacy viagra generic buy viagra pills

  25. order viagra without prescription viagragel viagra strengths

  26. cialis generic cialis south africa tadalafil ( cialis )

  27. viagra for no prisiption viagra in canada buy how to take viagra

  28. cialis cialis buy online generic cialis paypal

  29. viagra sales in australia viagra sub viagra blue vision

  30. 100 mg viagra order generic viagra online viagra with dapoxetine reviews

  31. viagra prolonged viagra/cialis black and gold 800 is viagra over the counter in mexico

  32. pharmacy today best canadian pharmacy pharmacy discount card

  33. pharmacy drug rx best drugstore lipstick

  34. best drugstore liquid eyeliner erectile dysfunction medications best drugstore moisturizer

  35. п»їviagra online canadian pharmacy cheap viagra online canadian pharmacy pharmacy coupons

  36. best ed pills ed medications best drugstore face moisturizer

  37. canadian online pharmacies drugstore near me discount pharmacy card

  38. erectile dysfunction drug ed pills online us pharmacy

  39. buy viagra usa online viagra w uk grapefruit and viagra buy viagra quick buy viagra online australia generic viagra viagra pills in ilkeston viagra 100mg price without prescription viagra no perscription viagra en uk viagra best price viagra 25mg no prescription viagra online buy paypal generic viagra 50mg viagra .com

  40. viagra substitute worldwide actual prescription cost of viagra viagra online highpoint viagra online canada paypal where to get viagra in bangalore buy generic viagra online in uk viagra for cheap how to buy viagra in shanghai where can i get viagra across the counter in the uk viagra from canada viagra in toronto about generic viagra viagra no prescription fast shipping viagra before and after pics buy generic viagra on line

  41. cialis viagra gr genaric viagra online buy viagra in canada hard for 36hr like viagra suppliers of generic viagra the effects that viagra and cialis have on women viagra without a prescripsion cocaine and viagra viagra online purchase belize viagra viagra free mail canada viagra for sale pay pal viagra&dapoxetine best prices in america for viagra buying inexpensive viagra

  42. viagra buy cheap drug categories viagra cialis ireland manufacturer viagra http://genqpviag.com/ - brand viagra ’

  43. viagra for sale malaysia what does a prescription for viagra cost viagra online canada no prescription http://acialaarx.com/ - viagra online generic ’

  44. generic viagra india online viagra free sample viagra online http://genericrxxx.com/ - viagra in kuwait ’

  45. black tab cialis viragecialis canadian cialis online http://cialijomen.com/ - cialis purchase online ’

  46. buy cialis 36 hour online free samples of cialis best prices cialis http://phrcialiled.com/ - i need cialis ’

  47. cialis 36 hour dosage cialis with dapoxetine australia overnight delivery cialis paypal http://21cialismen.com/ - buy cialis ’

  48. discount viagra buy viagra, canada buy viagra from germany http://llviabest.com/ - free viagra trials ’

  49. cialis professional cheap cialis tablets order cialis online http://mycialedst.com/ - does generic cialis work? ’

  50. cialis black wirkung cialis paypal bezahlen cialis online free shipping http://cialmenshoprx.com/ - cialis no perscrption ’

  51. generic cialis fast shipping windsor, ontario, canada pharmacy cialis cialis store in philippines http://sjcialis.com/ - buy cialis online in usa ’

  52. cheapest cialis tadalafil 20 mg cialis superactive cheap cialis australia http://loncialis.com/ - cialis generic 20mg ’

  53. viagra doses pfizer viagra with script cheapest soft viagra https://canadianpharmacy-usx.com/organic.htm - viagra boots ’

Leave a Reply