Hi John, John Summerfield wrote: > > summer at Mopoke:~> time bm.perl&time bm.perl&wait > [1] 3480 > [2] 3481 > > real 0m23.935s > user 0m23.689s > sys 0m0.004s > > real 0m25.906s > user 0m24.746s > sys 0m0.004s > [1]- Done time bm.perl > [2]+ Done time bm.perl What are the results for a single "time bm.perl" ? These are my results, first on a HT P4: root at ihbids /tmp# uname -a Linux ihbids.ihbi.qut.edu.au 2.6.9-42.0.2.ELsmp #1 SMP Wed Aug 23 00:17:26 CDT 2006 i686 i686 i386 GNU/Linux root at ihbids /tmp# time ./bm.perl uname -a real 0m12.783s user 0m12.765s sys 0m0.002s root at ihbids /tmp# time ./bm.perl & time ./bm.perl & wait [1] 29798 [2] 29799 real 0m21.422s user 0m21.395s sys 0m0.003s [1]- Done time ./bm.perl real 0m21.589s user 0m20.467s sys 0m0.003s [2]+ Done time ./bm.perl One a system with real SMP (Opteron, dual core, dual socket): root at basilisk /tmp# uname -a Linux basilisk.ihbi.qut.edu.au 2.6.9-34.0.2.ELsmp #1 SMP Fri Jul 7 18:22:55 CDT 2006 x86_64 x86_64 x86_64 GNU/Linux root at basilisk /tmp# time ./bm.perl real 0m14.309s user 0m14.095s sys 0m0.121s root at basilisk /tmp# time ./bm.perl & time ./bm.perl & wait [1] 26588 [2] 26589 real 0m14.232s user 0m14.178s sys 0m0.001s [1]- Done time ./bm.perl real 0m14.256s user 0m14.194s sys 0m0.026s [2]+ Done time ./bm.perl root at basilisk /tmp# time ./bm.perl & time ./bm.perl & time ./bm.perl & time ./bm.perl & wait [1] 26592 [2] 26593 [3] 26594 [4] 26595 real 0m14.164s user 0m14.125s sys 0m0.009s real 0m14.597s user 0m14.149s sys 0m0.071s real 0m15.020s user 0m14.335s sys 0m0.030s [1] Done time ./bm.perl [3]- Done time ./bm.perl [4]+ Done time ./bm.perl real 0m15.143s user 0m14.168s sys 0m0.196s [2]+ Done time ./bm.perl I believe my results show that HT does almost nothing at all. The P4 box does seem to have HT enabled - it is showing two cpus in /proc/cpuinfo and: root at ihbids /tmp# dmesg |grep 'CPU: L' CPU: L2 cache: 2048K CPU: L2 cache: 2048K Regards Robert -- Robert Stuart Systems Administrator Institute of Health and Biomedical Innovation