Dan,This is related to the undersized batch issue I mentioned in an earlier thread. From your data we can see that the batch (sample) size is 1. This is broken. It means that alternate batches will use PROT_NONE and PROT_READ | PROT_WRITE. I suspect one of these is cheap, and the other is not ... at least this would explain why you get two distinct timings with 50% of the samples in each.
This is another instance of a change in libMicro exposing some interesting behaviour (which seems to deserve further investigation). But it also points to more work needing doing on the new duration control code in 0.3.0.
Cheers, Phil Dan Price wrote:
I'm seeing the following libmicro computation regarding mprotect, which looks fishy to me. Interesting to note that libmicro eventually discards all of the results > 100 usecs, leading it to conclude that this system call is taking 1usec per call. Plus, there's a very odd distribution of times. Which seems out of whack. Any ideas what is going on here? (Playing with libmicro runs to demonstrate the difference between DEBUG and non-DEBUG kernels). -dp # bin/mprotect -E -C 200 -L -S -W -N mprot_tw128k -l 128k -I 2000 -w -t -f /dev/zero prc thr usecs/call samples errors cnt/samp size flagsmprot_tw128k 1 1 1.03400 201 0 1 131072 --w-t # # STATISTICS usecs/call (raw) usecs/call (outliers removed) # min 0.84400 0.84400 # max 229.14700 140.36000 # mean 54.06056 53.18948 # median 103.44900 1.03400 # stddev 54.06297 52.75775 # standard error 3.80386 3.72124 # 99% confidence level 8.84777 8.65562 # skew 0.14148 0.02044 # kurtosis -1.54415 -1.99042 # time correlation -0.01335 -0.02110 # # elasped time 0.01238 # number of samples 201 # number of outliers 1 # getnsecs overhead 170 # # DISTRIBUTION # counts usecs/call means # 101 0.00000 |******************************** 0.90348 # 0 4.00000 | - # 0 8.00000 | - # 0 12.00000 | - # 0 16.00000 | - # 0 20.00000 | - # 0 24.00000 | - # 0 28.00000 | - # 0 32.00000 | - # 0 36.00000 | - # 0 40.00000 | - # 0 44.00000 | - # 0 48.00000 | - # 0 52.00000 | - # 0 56.00000 | - # 0 60.00000 | - # 0 64.00000 | - # 0 68.00000 | - # 0 72.00000 | - # 0 76.00000 | - # 0 80.00000 | - # 0 84.00000 | - # 0 88.00000 | - # 0 92.00000 | - # 0 96.00000 | - # 22 100.00000 |****** 103.80795 # 67 104.00000 |********************* 105.83069 # # 11 > 95% |*** 111.40036 # # mean of 95% 49.81938 # 95th %ile 106.38900
smime.p7s
Description: S/MIME Cryptographic Signature
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