the crux with DMA

the crux with DMA

[martin f krafft]

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Hi folks,

I have two machines with 7200 UPM ATA drives. Both are running the
2.6.2 kernel. One has an AMD-768 IDE chipset and reiserfs, the other
a combination of VT82C586 and Promise 20269 with ext3.

Both machines seem to have a problem with DMA, which wasn't
a problem with the 2.4 kernel series. The symptoms are simple: if
I have DMA turned on, sustained high disk usage will cause complete
freezes in both machines. Sometimes, one gets a couple of kernel
oops before the eventual lockup, which is usually related to
journaling code, but it's never really the same. With a 2.4 kernel,
these lockups did not happen. With DMA turned off, I have also not
been able to reproduce the crashes.

I know that neither, reiserfs nor ext3, are high-performance, and
a switch to xfs has long been on my TODO list, but I first want to
get this problem worked out -- I can't mirror the disk otherwise
without crashing 40 times, so I can't create new filesystems.

Any advice is appreciated!

-- 
martin;              (greetings from the heart of the sun.)
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Re: the crux with DMA

[Hans Reiser]

martin f krafft wrote:

>.
>
>I know that neither, reiserfs nor ext3, are high-performance, 
>
both ext3 and reiserfs are higher performance than XFS for typical file 
sizes.  XFS does very well for streaming video though (as does reiser4).

Re: the crux with DMA

[martin f krafft]

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also sprach Hans Reiser <reiser@namesys.com> [2004.02.18.1949 +0100]:
> both ext3 and reiserfs are higher performance than XFS for typical file 
> sizes.  XFS does very well for streaming video though (as does reiser4).

How about large files (e.g. > 2Gb).

Do you have specs on your above statement? Not that I doubt
reiserfs, but I have been generally unhappy with its performance,
especially when huge files are involved. And I have suffered severe
corruption from a single bad block. A lot of people have suggested
using XFS. I am not a guru, so these statements are far from
educated.

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