2.6.26 kernel with Intel DMA patches
I've produced a 2.6.26 based kernel with the DMA engine patches from
Intel. Your Thecus N2100 will have considerably better hard drive
performance with this kernel. However, the patches are experimental
and not in the mainline kernel (see #444271 for some background on
this). I haven't seen any data corruption with the current version
of the patches, but please watch out for problems if you decide to
install this kernel.
I intend to maintain a 2.6.26 kernel with these DMA patches throughout
the lifetime of Debian lenny. When a new kernel update is made to
lenny, I will update my repository accordingly.
If you want to install this kernel, put the following line in
/etc/apt/sources.list
deb http://people.debian.org/~tbm/dma lenny main
Then run
apt-get update
When you upgrade your system (e.g. with apt-get upgrade), the kernel
with the DMA patches will be installed. Please note that you'll
receive a warning that the linux-image-2.6.26-1-iop32x package cannot
be authenticated. This is because my repository is not signed. You
can simply ignore this warning.
The repository also contains a kernel image for Marvell's Orion
platform. The DMA patches haven't had much testing on this platform,
but they seem to lead to some performance increase there too. So
those willing to experiment with their data can try the Orion kernel
too.
FWIW, here are some numbers I see on my Thecus N2100 (but the numbers
highly depend on your hard drive):
2.6.22
Timing cached reads: 62 MB in 2.02 seconds = 30.72 MB/sec
Timing buffered disk reads: 58 MB in 3.02 seconds = 19.21 MB/sec
Timing cached reads: 64 MB in 2.02 seconds = 31.75 MB/sec
Timing buffered disk reads: 58 MB in 3.03 seconds = 19.13 MB/sec
2.6.25
Timing cached reads: 126 MB in 2.02 seconds = 62.26 MB/sec
Timing buffered disk reads: 66 MB in 3.09 seconds = 21.35 MB/sec
Timing cached reads: 126 MB in 2.01 seconds = 62.71 MB/sec
Timing buffered disk reads: 62 MB in 3.01 seconds = 20.57 MB/sec
2.6.25 DMA
Timing cached reads: 328 MB in 2.00 seconds = 163.68 MB/sec
Timing buffered disk reads: 80 MB in 3.03 seconds = 26.40 MB/sec
Timing cached reads: 330 MB in 2.01 seconds = 164.38 MB/sec
Timing buffered disk reads: 82 MB in 3.04 seconds = 27.01 MB/sec
2.6.26
Timing cached reads: 126 MB in 2.01 seconds = 62.65 MB/sec
Timing buffered disk reads: 66 MB in 3.08 seconds = 21.40 MB/sec
Timing cached reads: 126 MB in 2.01 seconds = 62.57 MB/sec
Timing buffered disk reads: 66 MB in 3.09 seconds = 21.39 MB/sec
2.6.26 DMA
Timing cached reads: 346 MB in 2.00 seconds = 173.00 MB/sec
Timing buffered disk reads: 82 MB in 3.06 seconds = 26.77 MB/sec
Timing cached reads: 350 MB in 2.01 seconds = 174.53 MB/sec
Timing buffered disk reads: 80 MB in 3.08 seconds = 25.94 MB/sec
--
Martin Michlmayr
http://www.cyrius.com/
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