Subject: Re: [linux-audio-user] 2nd harddrive overhead
From: Mark Knecht (markknecht_AT_comcast.net)
Date: Fri Aug 27 2004 - 03:36:26 EEST
On Thu, 2004-08-26 at 10:19, Alastair Couper wrote:
> I have two hard drives, hda and hdb, both UDMA66. hda has the ext3 root
> partition, a swap partition, and a FAT32 partition. hdb just has one
> 10Meg FAT32 partition.
>
> When I stream a .wav file from the FAT32 partition on hda through say
> XMMS, the total system load is very low, just a few percent cpu load.
>
> When I do the same, but from hdb's FAT32 partition, the cpu load hovers
> at around 30-50%. What is responsible for all the extra cpu activity in
> reading from the 2nd harddrive ?
>
I would suspect that DMA is not enabled forthe slave drive, it's doing
PIO and you're running every byte from the drive through the processor
on its way to memory. Turn DMA on and none of the bytes go through the
processor. Just a guess...
- Mark
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