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+--- Thread: high iowait with livetv enabled? (/showthread.php?tid=206316)
high iowait with livetv enabled? - carl1jenn - 2014-10-13
Anyone else notice a high iowait with livetv enabled? I turned off livetv and my iowait goes back down to under 1%. With livetv enabled it goes up to 50% to 80% iowait.
btw I am on openelec version 4.2.1 = gotham 13.2, using an intel nuc booting off a 16gb usb stick.
RE: high iowait with livetv enabled? - nickr - 2014-10-13
I would say as a guess that the usb stick isn't fast enough for the disk reads/writes required by livetv.
Is this just when PVR starts up and gets EPG info from the backend and saves it to XBMC's own database?
As a comparison, I have 4.2.1 running from a hard drive on an atom/ion2 box with mythtv backend and don't see this problem.
Actually reading your openelec forum thread, your disk may be in need of repair:
[ 4.658636] EXT4-fs (sda1): couldn't mount as ext3 due to feature incompatibilities
[ 4.660006] EXT4-fs (sda1): couldn't mount as ext2 due to feature incompatibilities
[ 4.664738] EXT4-fs (sda1): mounted filesystem with ordered data mode. Opts: (null)
[ 4.863173] EXT4-fs (sda2): couldn't mount as ext3 due to feature incompatibilities
[ 4.864272] EXT4-fs (sda2): couldn't mount as ext2 due to feature incompatibilities
[ 4.874482] EXT4-fs (sda2): warning: mounting fs with errors, running e2fsck is recommended
Filesystem errors will elevate your iowait, and maybe the disk activity when PVR is enabled is pushing it over the edge.
RE: high iowait with livetv enabled? - carl1jenn - 2014-10-13
Actually I have 3 different intel nuc with the same 16gb stick. I noticed that one was not having the iowait issue, so I left that one alone and reinstalled one of the other two that was having the issue. Right after reinstall the iowait was back to normal but once I enabled livetv the iowait would jump back up to 6o% to 80%+ and would stay there.
also I see the iowait state with no pvr clients enabled. So I am not sure what the livetv function is doing at that point that is causing such high io.
and to directly answer your question, the iowait state goes to 60% to 80% soon as I enable livetv and stays there forever, it doesn't go back down to a normal state. This is also without a pvr client enbled.
As soon as I disable livetv, iowait state goes back down to normal.
RE: high iowait with livetv enabled? - nickr - 2014-10-13
You haven't addressed this
[ 4.874482] EXT4-fs (sda2): warning: mounting fs with errors, running e2fsck is recommended
RE: high iowait with livetv enabled? - carl1jenn - 2014-10-13
I am testing another intel nuc with a different 16gb usb stick. This one does not have the fs errors.