Hi Ole Should one use -j default or -j0 ?
Is there a benchmark test which shows that -j0 is always faster than default? Acording to $(grep -c proc /proc/cpuinfo) I have 6 cores. This should imply that my default is -j6. $ for N in $(seq -w 1000) ; do cp /big.html $N.html ; done $ time ls -U *.html | parallel --joblog jdefault.log gzip real 1m2.342s user 1m24.616s sys 0m4.352s $ rm *.gz $ for N in $(seq -w 1000) ; do cp /big.html $N.html ; done $ time ls -U *.html | parallel --joblog j0.log -j0 gzip parallel: Warning: Only enough file handles to run 252 jobs in parallel. parallel: Warning: Running 'parallel -j0 -N 252 --pipe parallel -j0' or parallel: Warning: raising ulimit -n or /etc/security/limits.conf may help. real 1m23.760s user 1m44.184s sys 0m4.692s I read this as the warning tells me if I tweak my system I can have more open files but by default an arbitrary system would perform better with -j default (in my case 6) than -j0. Am I doing something wrong? ./hans
