It looks like partitions are being reported correctly, just not the main
device
$ cat /proc/diskstats | awk '{print $3, $7, $11, $7+$11, $13, $14}' | grep nvme
nvme0n1 22988 457568 480556 2440737408 2441207708
nvme0n1p1 22988 339624 362612 528884 978496
nvme0n1p2 0 0 0 0 0
nvme0n1p5 0 0 0 4 4
Note that the $7+$11 column for n1p1 isn't that far off of $13
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https://bugs.launchpad.net/bugs/1790181
Title:
/proc/diskstats shows weird values
Status in linux package in Ubuntu:
Confirmed
Bug description:
For one block device on one of my servers munin shows abnormally high
latency.
When querying /proc/diskstats manually, the device in question shows:
8 32 sdc 973668 361965 64248290 10224376 755130 518162 22349256
1347171224 63 54302956 1357481880
Sanity check:
If I divide the 7th value by the 4th value I get a avg read latency of about
10.5 ms. That is somewhat in line with the Avg. Read IO Wait Time of 11.35 ms
that munin reports.
The problem:
If I divide the 11th value by the 8th value I get an avg write latency of
1789 ms. That is also close to the Avg. Write IO Wait Time of 1.60 s reported
by munin. Now this is an SD card and it is slow, but not THAT slow..
To confirm unexpected values, I measured some activity:
$ dd if=/dev/urandom of=testfile bs=1M count=100; time sync;
cat /proc/diskstats
100+0 records in
100+0 records out
104857600 bytes (105 MB, 100 MiB) copied, 18,7652 s, 5,6 MB/s
real 0m8,132s
user 0m0,000s
sys 0m0,007s
The reported time spent writing went from 1353896856 before the test to
1356759112 after the test.
The difference is 2862256 ms or about 2800 seconds that supposedly passed in
just over 26 real time seconds.
I repeated the test with count=1 and got 5780 ms IO write time reported in .7
s realtime.
#1297522 describes a similar error but I have no idea if the cause is related.
System information:
Description: Ubuntu 18.04.1 LTS
Release: 18.04
Linux 4.15.0-30-generic #32-Ubuntu SMP Thu Jul 26 17:42:43 UTC 2018
x86_64 x86_64 GNU/Linux
/dev/sdc is a Dell dual SD card module in RAID 1 mode with two Lexar 8GB U3
cards.
The system is a Dell R530.
---
ProblemType: Bug
AlsaDevices:
total 0
crw-rw---- 1 root audio 116, 1 Aug 11 22:30 seq
crw-rw---- 1 root audio 116, 33 Aug 11 22:30 timer
AplayDevices: Error: [Errno 2] No such file or directory: 'aplay': 'aplay'
ApportVersion: 2.20.9-0ubuntu7.2
Architecture: amd64
ArecordDevices: Error: [Errno 2] No such file or directory: 'arecord':
'arecord'
AudioDevicesInUse: Error: command ['fuser', '-v', '/dev/snd/seq',
'/dev/snd/timer'] failed with exit code 1:
DistroRelease: Ubuntu 18.04
HibernationDevice: RESUME=UUID=719079af-279c-46cd-9438-01086a2cb16e
InstallationDate: Installed on 2016-03-29 (885 days ago)
InstallationMedia: Ubuntu-Server 14.04.3 LTS "Trusty Tahr" - Beta amd64
(20150805)
MachineType: Dell Inc. PowerEdge R530
Package: linux (not installed)
PciMultimedia:
ProcFB: 0 mgadrmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.15.0-30-generic
root=UUID=9be44daa-0a66-486f-9fac-ff0814849ed3 ro crashkernel=384M-:128M
crashkernel=384M-:128M crashkernel=384M-:128M crashkernel=384M-:128M
crashkernel=384M-2G:128M,2G-:256M crashkernel=384M-2G:128M,2G-:256M
crashkernel=384M-2G:128M,2G-:256M crashkernel=384M-2G:128M,2G-:256M
crashkernel=384M-2G:128M,2G-:256M
ProcVersionSignature: Ubuntu 4.15.0-30.32-generic 4.15.18
RelatedPackageVersions:
linux-restricted-modules-4.15.0-30-generic N/A
linux-backports-modules-4.15.0-30-generic N/A
linux-firmware 1.173.1
RfKill: Error: [Errno 2] No such file or directory: 'rfkill': 'rfkill'
Tags: bionic
Uname: Linux 4.15.0-30-generic x86_64
UnreportableReason: This report is about a package that is not installed.
UpgradeStatus: Upgraded to bionic on 2018-08-11 (19 days ago)
UserGroups: adm cdrom dip libvirt libvirtd lpadmin plugdev sambashare sudo
_MarkForUpload: False
dmi.bios.date: 10/05/2015
dmi.bios.vendor: Dell Inc.
dmi.bios.version: 1.5.4
dmi.board.name: 0HFG24
dmi.board.vendor: Dell Inc.
dmi.board.version: A01
dmi.chassis.type: 23
dmi.chassis.vendor: Dell Inc.
dmi.modalias:
dmi:bvnDellInc.:bvr1.5.4:bd10/05/2015:svnDellInc.:pnPowerEdgeR530:pvr:rvnDellInc.:rn0HFG24:rvrA01:cvnDellInc.:ct23:cvr:
dmi.product.name: PowerEdge R530
dmi.sys.vendor: Dell Inc.
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