Messages in this thread | | | From | Paolo Ornati <> | Subject | Re: Strange IDE performance change in 2.6.1-rc1 (again) | Date | Fri, 2 Jan 2004 22:04:27 +0100 |
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On Friday 02 January 2004 19:08, Ed Sweetman wrote: > > > Note, sometimes when moving backwards back to a lower readhead my speed > does not decrease to the values you see here. readahead on my system > always goes up (on avg) with higher readahead numbers, maxing at 8192. > No matter the buffer size or speed or position the ide drive is in. > > hdparm -t is difficult to get really accurate, which is why they suggest > running it multiple times. I see differences of 4MB/sec on subsequent > runs without changing anything. run hdparm -t at least 3-4 times for > each readahead value. > > I suggest trying 128, 256,512,8192 as values for readahead and skip all > those crap numbers in between. > > > if you still see on avg lower numbers on the top end, try nicing hdparm > to -20. Also, update to a newer hdparm. hdparm v5.4, you seem to be > using an older one. >
ok, hdparm updated to v5.4
and this is the new script: _____________________________________________________________________ #!/bin/bash
# This script assumes hdparm v5.4
NR_TESTS=3 RA_VALUES="64 128 256 8192"
killall5 sync hdparm -a 0 /dev/hda > /dev/null hdparm -t /dev/hda > /dev/null
for ra in $RA_VALUES; do hdparm -a $ra /dev/hda > /dev/null; echo -n $ra$'\t'; tot=0; for i in `seq $NR_TESTS`; do tmp=`nice -n '-20' hdparm -t /dev/hda|grep 'Timing'|tr -d ' '|cut -d'=' -f2|cut -d'M' -f1`; tot=`echo "scale=2; $tot+$tmp" | bc`; done; s=`echo "scale=2; $tot/$NR_TESTS" | bc`; echo $s; done _____________________________________________________________________
The results are like the previous.
2.6.0: 64 31.91 128 31.89 256 26.22 # during the transfer HD LED blinks 8192 26.26 # during the transfer HD LED blinks
2.6.1-rc1: 64 25.84 # during the transfer HD LED blinks 128 25.85 # during the transfer HD LED blinks 256 25.90 # during the transfer HD LED blinks 8192 26.42 # during the transfer HD LED blinks
I have tried with and without "nice -n '-20'" but without any visible changes.
Performance with 2.4: with kernel 2.4.23 && readahead = 8 I get 31.89 MB/s... changing readahead doesn't seem to affect the speed too much.
Bye
-- Paolo Ornati Linux v2.4.23
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