Messages in this thread |  | | From | ganesh@cse ... | Date | Wed, 19 Feb 1997 10:02:04 +0530 (IST) | Subject | Re: Improving HardDisks... |
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Gabriele Paciucci <paciucci@pcainf1.ing.uniroma1.it> wrote: > 1)Why don't Linux use the Bios settings ? > 2)Why -d1 -X34 decrease ? > 3)How to set -m16 -c3 -X12 to HD finally ?
A2. -d1 -X34 is supposed to put it into DMA mode 2, and using_dma should be 1 if it did. It's 0, so something went wrong I guess. A3. Put it in your /etc/rc.d/rc.local
Note that throughput is not everything : some of those options don't affect throughput much, but they reduce "system time" i.e. time spent in kernel mode for interrupt handling etc. This is a big win since some other process could run in the time which otherwise would be spent in disk I/O.
The following very rough measurement was done on a P-100 8MB IDE Seagate ST31276A, kernel 2.0.29 with the Triton stuff, after booting with init=/bin/bash. I haven't averaged or anything, but these are fairly representative :
With default settings (everything off except readahead) time hdparm -t /dev/hda
Throughput 3.66 MB/sec Time 0.06user 3.55system 0:07.31elapsed 49%CPU No. of ide0 interrupts 32810
With hdparm -c1 -m16 -d1 -X34 /dev/hda
Throughput 4.69 MB/sec Time 0.04user 0.88system 0:06.59elapsed 13%CPU No. of ide0 interrupts 260 !!
This is a HUGE order of magnitude improvement ! This deserves to be better documented ... right now it's just in the hdparm manpage AFAIK. I don't think too many people know about this ...
-- ganesh
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