Hope that was as fun to write, as it was for me to read! Thanks. On Wed, Feb 6, 2019 at 12:50 AM ToddAndMargo via perl6-users < perl6-users@perl.org> wrote:
> On 2/6/19 12:44 AM, ToddAndMargo via perl6-users wrote: > > On 2/5/19 11:56 PM, ToddAndMargo via perl6-users wrote: > >> On 2/5/19 8:34 PM, ToddAndMargo via perl6-users wrote: > >>>>> > >>>>> > >>>>> On Sun, Feb 3, 2019 at 9:36 PM ToddAndMargo via perl6-users > >>>>> <perl6-users@perl.org <mailto:perl6-users@perl.org>> wrote: > >>>>> > >>>>> Hi All, > >>>>> > >>>>> If I have a variable of type Buf which 10000000 bytes in it > >>>>> and I find the five bytes I want, is it faster, slower, > >>>>> or no difference in speed to overwrite the same variable > >>>>> with the five bytes? Or is it faster to put the five bytes > >>>>> from the first variable into a second variable? > >>>>> > >>>>> Many thanks, > >>>>> -T > >>>>> > >>> > >>> On 2/5/19 8:42 AM, yary wrote: > >>>> There are modules to time two pieces of code and show the difference > >>>> https://github.com/perl6-community-modules/perl6-Benchy > >>>> https://github.com/tony-o/perl6-bench > >>>> > >>>> You can write up the two versions you're thinking of, feed them to > >>>> the benchmark module, and show us what you find! > >>>> > >>>> -y > >>> > >>> > >>> Hi Yary, > >>> > >>> Thank you! > >>> > >>> Apparently, overwriting the original buffer only change the > >>> structures pointers, which is almost instantaneous. > >>> > >>> And you taught me something new today! > >>> > >>> -T > >>> > >>> > >>> <code VarTest.pl6> > >>> > >>> #!/usr/bin/env perl6 > >>> > >>> use Bench; > >>> > >>> my IO::Handle $HaystackHandle = open( "/home/temp/procexp64.exe", > >>> :bin, :ro ); > >>> my Buf $Haystack = $HaystackHandle.read( 3000000 ); > >>> $HaystackHandle.close; > >>> > >>> my Buf $Needle; > >>> > >>> my $b = Bench.new; > >>> > >>> sub Another() { $Needle = $Haystack.subbuf( 0x14FFAC .. 0x145FAC ); } > >>> sub Same() { $Haystack = $Haystack.subbuf( 0x14FFAC .. 0x145FAC ); } > >>> > >>> say "first copies to a new variable; second overwrites the same > >>> variable"; > >>> $b.timethese( 100000, { > >>> first => sub { Another; }, > >>> second => sub { Same; }, > >>> }); > >>> > >>> </code VarTest.pl6> > >>> > >>> > >>> $ VarTest.pl6 > >>> first copies to a new variable; second overwrites the same variable > >>> Benchmark: > >>> Timing 100000 iterations of first, second... > >>> first: 0.021 wallclock secs (0.021 usr 0.000 sys 0.021 cpu) @ > >>> 4676612.262/s (n=100000) > >>> second: 0.000 wallclock secs (0.000 usr 0.000 sys 0.000 cpu) > >> > >> > >> You guys catch my mistake? It is only valid for one iteration. > >> Chuckle. A rewrite is in order. > > > > > > <code VarTest.pl6> > > #!/usr/bin/env perl6 > > > > use Bench; > > > > my IO::Handle $HaystackHandle = open( "/home/temp/procexp64.exe", :bin, > > :ro ); > > my Buf $Haystack = $HaystackHandle.read( 3000000 ); > > $HaystackHandle.close; > > > > my Buf $SubBuf; > > my $b = Bench.new; > > > > sub Another() { my Buf $b = $Haystack; my Buf $Needle = $b.subbuf( > > 0x14FFAC .. 0x145FAC ); } > > sub Same() { my Buf $b = $Haystack; $b = $b.subbuf( 0x14FFAC .. > > 0x145FAC ); } > > > > say "first copies to a new variable; second overwrites the same > variable"; > > $b.timethese( 100000, { > > first => sub { $SubBuf = Another(); }, > > second => sub { $SubBuf = Same(); }, > > }); > > </code VarTest.pl6> > > > > > > > > $ VarTest.pl6 > > first copies to a new variable; second overwrites the same variable > > Benchmark: > > Timing 100000 iterations of first, second... > > first: 0.051 wallclock secs (0.054 usr 0.003 sys 0.057 cpu) @ > > 1965370.177/s (n=100000) > > second: 0.052 wallclock secs (0.045 usr 0.001 sys 0.046 cpu) @ > > 1926856.526/s (n=100000) > > > > > > Virtually no difference > > And it would help if I did not reuse variable names. > > A little bit of difference: > > New variable = 0.053 wallclock secs > Overwrite = 0.085 wallclock secs > > > <code VarTest.pl6> > #!/usr/bin/env perl6 > > use Bench; > > my IO::Handle $HaystackHandle = open( "/home/temp/procexp64.exe", :bin, > :ro ); > my Buf $Haystack = $HaystackHandle.read( 3000000 ); > $HaystackHandle.close; > > my Buf $SubBuf; > my $b = Bench.new; > > sub Another() { my Buf $bb = $Haystack; my Buf $Needle = $bb.subbuf( > 0x14FFAC .. 0x145FAC ); } > sub Same() { my Buf $bb = $Haystack; $bb = $bb.subbuf( 0x14FFAC .. > 0x145FAC ); } > > say "first copies to a new variable; second overwrites the same variable"; > $b.timethese( 100000, { > first => sub { $SubBuf = Another(); }, > second => sub { $SubBuf = Same(); }, > }); > </code VarTest.pl6> > > > > $ VarTest.pl6 > first copies to a new variable; second overwrites the same variable > Benchmark: > Timing 100000 iterations of first, second... > first: 0.053 wallclock secs (0.052 usr 0.003 sys 0.055 cpu) @ > 1899696.049/s (n=100000) > second: 0.085 wallclock secs (0.078 usr 0.000 sys 0.078 cpu) @ > 1180442.430/s (n=100000) > > > > > -- > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > Computers are like air conditioners. > They malfunction when you open windows > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ >
