Revised code to test drive speed in initrd

The 'init' script in the initrd takes three spot speed readings, using the 'dd' "skip" feature. The intention of this is that on a HDD it will cause slow readings as the physical arm will have to move to different tracks on the magnetic platters. However, I have a suspicion that skip causes weirdness with SSDs.

So, have changed the code to just one one 118MB read, without skip:

###speed test###
###############################################################################
#note: dd in coreutils has different output, "s" instead of "seconds"...
##get average of three timings...
#TIMEs1="$(dd if=/dev/${WKG_DRV} of=/dev/null bs=1024 count=64 iflag=skip_bytes skip=805306368 2>&1 | grep -o '[0-9.]* [second]*s,' | cut -f 1 -d ' ')"
#TIMEs2="$(dd if=/dev/${WKG_DRV} of=/dev/null bs=1024 count=64 iflag=skip_bytes skip=1610612736 2>&1 | grep -o '[0-9.]* [second]*s,' | cut -f 1 -d ' ')"
#TIMEs3="$(dd if=/dev/${WKG_DRV} of=/dev/null bs=1024 count=64 iflag=skip_bytes skip=2415919104 2>&1 | grep -o '[0-9.]* [second]*s,' | cut -f 1 -d ' ')"
#TIMEs="$(dc -e "${TIMEs1} ${TIMEs2} + ${TIMEs3} + p")"
##...sata hdd: 0.018864, usb3.0 ssd: 0.003258, pcie nvme ssd: 0.001403, cheap emtec usb2 flash stick: 0.013006, sandisk ultra usb3.0 flash stick: 0.004393, usb3.0 hdd: 0.035629
#TIME10k=$(dc -e"${TIMEs} 10000 * 3 / p" | cut -f 1 -d '.') #cheap flash stick: usb2=140 usb3=77, be usb3=41, sandisk-extreme usb3=42, internal eMMC: 

#20260102 suspicion dd skip causing weirdness on ssd's, just do one big read...
sleep 0.1
TIMEs="$(dd if=/dev/${WKG_DRV} of=/dev/null bs=1M count=118 2>&1 | grep -o '[0-9.]* [second]*s,' | cut -f 1 -d ' ')"
TIME10k=$(dc -e"${TIMEs} 100 * p" | cut -f 1 -d '.')
echo "Working drive read speed test (lower the better): ${TIME10k}"

I only have three computers to test on; had several but recently gave them away and binned a couple of very old ones. Have done a radical cleanup of my premises. Anyway, testing on two of my computers, Zenbook and Aspire3 laptops, giving consistent results.    

Tags: easy