User Tools

Site Tools


Sidebar

software:io_benchmark

What is this?

My notes on basic i/o benchmarks on linux/unix systems.

Writing a file without sync is fast ofcourse:

time dd if=/dev/zero of=file bs=512M count=1

So sync should be used, using one of these variants:

sync; time bash -c 'dd if=/dev/zero of=file bs=512M count=1; sync'
time dd if=/dev/zero of=file bs=512M count=1 oflag=direct
# capturing data
for i in {1..11}; do time dd if=/dev/zero of=file bs=1G count=6 oflag=direct 2>&1; done | tee time.txt
vmstat 10 | tee vmstat.txt
iostat -x 10 sda2 | tee iostat.txt


# calculating average time:
# cat time_ht |grep real|sed -e 's,.*m,,' -e 's,s,,'  | \
#   awk '{if(min==""){min=max=$1}; if($1>max) {max=$1}; if($1< min) {min=$1}; total+=$1; count+=1} END {print total/count, min, max}'

# suming up wait from vmstat
# manually removed entries at beginning/end of file that were bevore/after the dd run
# cat vmstat_ht |egrep -v '^procs|^ r  b'|awk '{print $16}' | \
#   awk '{if(min==""){min=max=$1}; if($1>max) {max=$1}; if($1< min) {min=$1}; total+=$1; count+=1} END {print total/count, min, max}'
software/io_benchmark.txt ยท Last modified: 2015/08/11 20:32 (external edit)