# Disk throughput problem (DV capture).

## destroyedlolo

Hello,

I'm facing some problems to capture DV videos using Kino : when data have to be writen to disk, the capture hangs fews seconds, the CPU usage fall from about 100% to 20%  and the frames corresponding to this periodes are lost.

My configuration :

venerable Athlon 1.1Ghz

1.5 Go memory, obviously not swaping

system on an SCSI disk

capture on an IDE (PATA) disk, read performances : 50 MB (I duno the write performances as Disk utils needs an empty disk).

Under Gentoo :

Kino 1.3.4

kernel 3.0.6

LXTE/openbox

Under Ubuntu :

Kino 1.3.3

Kernel 2.6.31-23

Gnome 2

I think it's a problem of configuration regarding disk access as I don't have the problem when booting on Ubuntu.

What I can say is writing internal is longer on Gentoo but time to write is longer as well (I think it's because more caches are used under Gentoo).

Any tip ?

Thanks

Laurent

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## John R. Graham

What filesystem?

- John

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## destroyedlolo

Ext4 (formated by Ubuntu's installer).

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## destroyedlolo

Nobody has a tip ? It's very anoying  :Sad: 

Bye

Laurent

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## destroyedlolo

I found this interesting link, especially the part "Tuning Recommendations for write-heavy operations".

 can I change the proposed settings on the fly and how ?

 can I set them only for 1 disk (I don't think so, but who knows ...).

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## destroyedlolo

Well well well, no response good response as the French proverb says.

I did some tests on my own. And it seems :

```
sysctl -w vm.dirty_background_ratio=1
```

prevents this issue.

During my test, I can see some visual lags in Kino but "missed frame" counter stays at 0 and the resulting DV seems correct in VLC.

I think it's because my CPU power is on the edge but is still enough to avoid any loss   :Very Happy: 

I'll try to retrieve 1h video and will report here, just in case it can help someone.

By the way, setting 1 is a bit brutal : I'm not sure intermediate will improve anything ... as I don't have enough horsepower to run anything in parallel ...

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