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Re: [lmi] [lmi-commits] master 9c510ad 16/22: Measure elapsed time for M

From: Greg Chicares
Subject: Re: [lmi] [lmi-commits] master 9c510ad 16/22: Measure elapsed time for MD5 data-file validation
Date: Mon, 30 Mar 2020 13:26:42 +0000
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.5.0

On 2020-03-30 00:34, Greg Chicares wrote:
> On 2020-03-29 17:58, Vadim Zeitlin wrote:
>>  In fact, the main reason for writing this reply is that I'm surprised by
>> how long it takes to compute the hash. Using "openssl speed md5", I get
>> ~300MB/s for 64 byte blocks and while I don't know how big the files we're
>> verifying are exactly, I'm pretty sure that they're nowhere close to 30MB
>> in size. So I wonder if it could be useful to profile the code doing this
>> calculation to check if we're not doing something stupid?
> Sounds worthwhile.

Here's evidence that suggests our self-built standalone md5sum program
is as fast as the one in gnu coreutils. Summary:

   time  program used with "maximal" dataset
  ----- ------------------------------------
  0.194 wine lmi_md5sum.exe [i686]
  0.190 wine lmi_md5sum.exe [x86_64]
  0.200 wine md5sum.exe [i686 binary from the following URL]
  0.085 debian native md5sum

so it looks like most of the elapsed time is 'wine' overhead
(which of course wouldn't exist for msw end users).


These measurements use the "maximal" dataset described in my earlier
email, i.e., a current production distribution including every known
product, all obfuscated MST files, and the no-longer-needed md5sum
binary. As discussed in private email, I've shared [obfuscated] copies
of all these 347 files with a distinctive '.xyz' suffix.

# wine, self-built msw program, i686
/opt/lmi/data[0]$echo $LMI_TRIPLET
/opt/lmi/data[0]$time wine ./eraseme_lmi_md5sum.exe *.xyz |wc -l
wine ./eraseme_lmi_md5sum.exe *.xyz  0.12s user 0.05s system 86% cpu 0.194 total
wc -l  0.01s user 0.00s system 3% cpu 0.194 total

# wine, self-built msw program, x86_64
/opt/lmi/data[0]$. /opt/lmi/src/lmi/set_toolchain.sh
/opt/lmi/data[0]$time wine ./eraseme_lmi_x86_64_md5sum.exe *.xyz |wc -l
wine ./eraseme_lmi_x86_64_md5sum.exe *.xyz  0.08s user 0.08s system 86% cpu 
0.190 total
wc -l  0.01s user 0.00s system 4% cpu 0.189 total

# wine, historical downloaded msw program, i686
/opt/lmi/data[0]$time wine /cache_for_lmi/downloads/md5sum.exe *.xyz |wc -l
wine /cache_for_lmi/downloads/md5sum.exe *.xyz  0.14s user 0.03s system 84% cpu 
0.200 total
wc -l  0.00s user 0.00s system 1% cpu 0.200 total

# debian-testing native, x86_64
/opt/lmi/data[0]$time md5sum *.xyz |wc -l
md5sum *.xyz  0.07s user 0.01s system 99% cpu 0.085 total
wc -l  0.00s user 0.00s system 8% cpu 0.085 total

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