[boost] Re: What is a secret of mpl::set?

From: Alexander Nasonov (alnsn_at_[hidden])
Date: 2004-11-30 18:05:50

Alexander Nasonov wrote:
> David Abrahams wrote:
> > The tiny prototype that started all this is at: 
> > http://lists.boost.org/MailArchives/boost/msg53032.php
> 
> Thanks, Dave. This gives me an idea.

Now I don't think I found a good idea, forget it. But I've tried another
idea:
If all functions have same arity, signatures of several functions can be
deduced in one call. This improves performance for huge function sets.

In the end of my post you'll find numbers for algorithm "unique" based
on typeof and mpl::set with and w/o this optimization.  Unique signatures
are at 1, 2, 10, 39 and 200.

Here we go:

# init 1
# swapoff -a
# cpuspeedy max

# cat /proc/meminfo
MemTotal:       516012 kB
MemFree:        496272 kB
Buffers:           740 kB
Cached:           6308 kB
SwapCached:          0 kB
Active:           5612 kB
Inactive:         3240 kB
HighTotal:           0 kB
HighFree:            0 kB
LowTotal:       516012 kB
LowFree:        496272 kB
SwapTotal:           0 kB
SwapFree:            0 kB
Dirty:              76 kB
Writeback:           0 kB
Mapped:           2752 kB
Slab:             6480 kB
Committed_AS:     5540 kB
PageTables:        164 kB
VmallocTotal:   516020 kB
VmallocUsed:     35040 kB
VmallocChunk:   480456 kB

# cat /proc/cpuinfo
processor	: 0
vendor_id	: GenuineIntel
cpu family	: 6
model		: 9
model name	: Intel(R) Pentium(R) M processor 1300MHz
stepping	: 5
cpu MHz		: 1296.046
cache size	: 1024 KB
fdiv_bug	: no
hlt_bug		: no
f00f_bug	: no
coma_bug	: no
fpu		: yes
fpu_exception	: yes
cpuid level	: 2
wp		: yes
flags		: fpu vme de pse tsc msr mce cx8 apic mtrr pge mca cmov pat clflush dts acpi mmx fxsr sse sse2 tm pbe tm2 est
bogomips	: 2555.90

$ g++ -v
Reading specs from /usr/lib/gcc-lib/i686-pc-linux-gnu/3.3.4/specs
Configured with: /var/tmp/portage/gcc-3.3.4-r1/work/gcc-3.3.4/configure --prefix=/usr --bindir=/usr/i686-pc-linux-gnu/gcc-bin/3.3 --includedir=/usr/lib/gcc-lib/i686-pc-linux-gnu/3.3.4/include --datadir=/usr/share/gcc-data/i686-pc-linux-gnu/3.3 --mandir=/usr/share/gcc-data/i686-pc-linux-gnu/3.3/man --infodir=/usr/share/gcc-data/i686-pc-linux-gnu/3.3/info --enable-shared --host=i686-pc-linux-gnu --target=i686-pc-linux-gnu --with-system-zlib --enable-languages=c,c++,f77 --enable-threads=posix --enable-long-long --disable-checking --disable-libunwind-exceptions --enable-cstdio=stdio --enable-version-specific-runtime-libs --with-gxx-include-dir=/usr/lib/gcc-lib/i686-pc-linux-gnu/3.3.4/include/g++-v3 --with-local-prefix=/usr/local --enable-shared --enable-nls --without-included-gettext --disable-multilib --enable-__cxa_atexit --enable-clocale=generic
Thread model: posix
gcc version 3.3.4 20040623 (Gentoo Hardened Linux 3.3.4-r1, ssp-3.3.2-2, pie-8.7.6)

$ time g++ -I../../.. stress_unique.cpp

Number of overloads        uniform_row_earch  universal_search
passed to algorithm/total  seconds            seconds
-------------------------  -----------------  ----------------
200/200                    8                  13
300/300                    15                 26
400/400                    24                 43
500/500                    35                 65
600/600                    49                 94
700/700                    66                 128

200/500                    15                 27
300/500                    21                 39
400/500                    28                 52

Metaprogramming can process huge volume of data!

-- 
Alexander Nasonov