A quick meaningless benchmark showed a slight perfomance hit.
Here's 10 runs of "hackbench 50" using the two part 5 byte nop:
run 1
Time: 4.501
run 2
Time: 4.855
run 3
Time: 4.198
run 4
Time: 4.587
run 5
Time: 5.016
run 6
Time: 4.757
run 7
Time: 4.477
run 8
Time: 4.693
run 9
Time: 4.710
run 10
Time: 4.715
avg = 4.6509
And 10 runs using the above 5 byte nop:
run 1
Time: 4.832
run 2
Time: 5.319
run 3
Time: 5.213
run 4
Time: 4.830
run 5
Time: 4.363
run 6
Time: 4.391
run 7
Time: 4.772
run 8
Time: 4.992
run 9
Time: 4.727
run 10
Time: 4.825
avg = 4.8264
# cat /proc/cpuinfo
processor : 0
vendor_id : AuthenticAMD
cpu family : 15
model : 65
model name : Dual-Core AMD Opteron(tm) Processor 2220
stepping : 3
cpu MHz : 2799.992
cache size : 1024 KB
physical id : 0
siblings : 2
core id : 0
cpu cores : 2
apicid : 0
initial apicid : 0
fdiv_bug : no
hlt_bug : no
f00f_bug : no
coma_bug : no
fpu : yes
fpu_exception : yes
cpuid level : 1
wp : yes
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca
cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt
rdtscp lm 3dnowext 3dnow pni cx16 lahf_lm cmp_legacy svm extapic
cr8_legacy
bogomips : 5599.98
clflush size : 64
power management: ts fid vid ttp tm stc
There's 4 of these.
Just to make sure, I ran the above nop test again:
[ this is reverse from the above runs ]
run 1
Time: 4.723
run 2
Time: 5.080
run 3
Time: 4.521
run 4
Time: 4.841
run 5
Time: 4.696
run 6
Time: 4.946
run 7
Time: 4.754
run 8
Time: 4.717
run 9
Time: 4.905
run 10
Time: 4.814
avg = 4.7997
And again the two part nop:
run 1
Time: 4.434
run 2
Time: 4.496
run 3
Time: 4.801
run 4
Time: 4.714
run 5
Time: 4.631
run 6
Time: 5.178
run 7
Time: 4.728
run 8
Time: 4.920
run 9
Time: 4.898
run 10
Time: 4.770
avg = 4.757
This time it was close, but still seems to have some difference.
heh, perhaps it's just noise.
-- Steve
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