Hi John,
John Summerfield wrote:
summer@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@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@ihbids /tmp# time ./bm.perl
uname -a
real 0m12.783s
user 0m12.765s
sys 0m0.002s
root@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@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@basilisk /tmp# time ./bm.perl
real 0m14.309s
user 0m14.095s
sys 0m0.121s
root@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@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@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
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