** Also affects: linux (Ubuntu Bionic)
Importance: Undecided
Status: New
--
You received this bug notification because you are a member of Kernel
Packages, which is subscribed to linux in Ubuntu.
https://bugs.launchpad.net/bugs/1898786
Title:
Issue with bcache bch_mca_scan causing huge IO wait
Status in linux package in Ubuntu:
Confirmed
Status in linux source package in Bionic:
New
Bug description:
Hello,
In short, we faced an issue with a huge IO wait on a bionic Ubuntu
4.15.0-118.119-generic kernel.
This is the full list of process and the kernel function they were stuck in
[0].
The main issue can probably be summarized by this perf reports
* first identify that the cpu are stuck in idle because of something[1]
* second, see what kernel function seems to stuck the process kswapd0 and
kswapd1 [2].
We could see that this seems to be the mutex_lock in the bch_mca_scan
function [3].
After running the command:
| sudo bash -c "echo 1 > /sys/fs/bcache/f1a1e8cb-3e6b-40ea-852e-
583c48d0c2b8/internal/btree_shrinker_disabled"
The server started to respond normally and the IO wait dropped significantly
[0]: https://pastebin.canonical.com/p/wYYKwHdRXk/
[1]: https://pastebin.canonical.com/p/n2Tw57QyBC/
[2]: https://pastebin.canonical.com/p/3QqFTfdHhX/
[3]:
https://git.launchpad.net/~ubuntu-kernel/ubuntu/+source/linux/+git/bionic/tree/drivers/md/bcache/btree.c?h=Ubuntu-4.15.0-118.119#n674
====================
$ cat /proc/version_signature
Ubuntu 4.15.0-118.119-generic 4.15.18
ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: linux-image-4.15.0-118-generic 4.15.0-118.119
ProcVersionSignature: User Name 4.15.0-118.119-generic 4.15.18
Uname: Linux 4.15.0-118-generic x86_64
AlsaDevices:
total 0
crw-rw---- 1 root audio 116, 1 Sep 29 10:04 seq
crw-rw---- 1 root audio 116, 33 Sep 29 10:04 timer
AplayDevices: Error: [Errno 2] No such file or directory: 'aplay': 'aplay'
ApportVersion: 2.20.9-0ubuntu7.16
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:
Date: Tue Oct 6 20:36:18 2020
IwConfig: Error: [Errno 2] No such file or directory: 'iwconfig': 'iwconfig'
MachineType: HP ProLiant DL380 G7
PciMultimedia:
ProcFB: 0 radeondrmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.15.0-118-generic
root=UUID=c6ad1629-a506-4043-a339-6d57f0708d12 ro console=ttyS1,115200 nosplash
RelatedPackageVersions:
linux-restricted-modules-4.15.0-118-generic N/A
linux-backports-modules-4.15.0-118-generic N/A
linux-firmware 1.173.18
RfKill: Error: [Errno 2] No such file or directory: 'rfkill': 'rfkill'
SourcePackage: linux
UpgradeStatus: Upgraded to bionic on 2019-09-27 (375 days ago)
dmi.bios.date: 05/05/2011
dmi.bios.vendor: HP
dmi.bios.version: P67
dmi.chassis.type: 23
dmi.chassis.vendor: HP
dmi.modalias:
dmi:bvnHP:bvrP67:bd05/05/2011:svnHP:pnProLiantDL380G7:pvr:cvnHP:ct23:cvr:
dmi.product.family: ProLiant
dmi.product.name: ProLiant DL380 G7
dmi.sys.vendor: HP
To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1898786/+subscriptions
--
Mailing list: https://launchpad.net/~kernel-packages
Post to : [email protected]
Unsubscribe : https://launchpad.net/~kernel-packages
More help : https://help.launchpad.net/ListHelp
