####### shmem-init.pl ############################ #!/usr/bin/perl use warnings; use strict; use Time::HiRes qw( gettimeofday usleep ); use Fcntl qw( :DEFAULT :flock ); ## Part of core perl use IPC::SysV qw(IPC_STAT IPC_PRIVATE IPC_CREAT IPC_EXCL S_IRUSR S_IWUSR IPC_RMID); # see "perldoc perlfunc /shmget" and "perldoc perlipc /SysV" # big difference from c is attach and detach is automatic in Perl # it attaches to read or write, then detaches my $go = 1; $SIG{INT} = sub{ $go = 0; &close_m(); #close up the shared mem exit; }; my $segment_hbytes = 0x640; # hex bytes, a multiple of 4k my ($segment_id, $segment_size) = &init_m($segment_hbytes); print "shmid-> $segment_id\tsize-> $segment_size\n"; # Counter Elapsed time Writes/second # ----------------------------------------- my $stime = gettimeofday; my $i = 0; # Result: 2000000 9.27134203910828 215718/second while($go) { &write_m($i); $i++; if ( $i >= 2_000_000 ) { $stime = gettimeofday - $stime; my $rpm = int( 2_000_000 / $stime ); print "$i\t$stime\t$rpm/second\n\n"; last; } #select(undef,undef,undef,.001); last if ! $go; } our $indexdb; # Counter Elapsed time Writes/second # ----------------------------------------- my $file = "/dev/shm/FlexBase/__env.index"; # Result: 2000000 5.73024797439575 349025/second # my $file = "/__env.index"; # Result: 2000000 6.88051080703735 290676/second # my $file = "/flexvault/__env.index"; # Result: 2000000 9.02671384811401 221564/second open( $indexdb,"+<", $file ) or die "Not open: $!"; $stime = gettimeofday; $i = 0; while( 1 ) { &write_mem($i); $i++; if ( $i >= 2_000_000 ) { $stime = gettimeofday - $stime; my $rpm = int( 2_000_000 / $stime ); print "$i\t$stime\t$rpm/second\n"; last; } } close $indexdb; exit; sub write_mem() { our $indexdb; # Write a string to the shared file. my $message = shift; if ( flock( $indexdb, LOCK_EX ) ) { my $ret = sysseek( $indexdb, 0, 0); # move to beginning of file if ( ! defined $ret ) { die "O04. sysseek failed: $!"; } $ret = syswrite ( $indexdb, $i, length($i) ); if ( $ret != length($i) ) { die "O05. syswrite failed! $!"; } } ## ## Make test ( 1==1 ) to verify syswrite worked correctly. ## Make test ( 1==2 ) to test speed of syswrite to filesystem. ## if ( ( 1==2 )&&( flock( $indexdb, LOCK_SH ) ) ) { my $ret = sysseek( $indexdb, 0, 0); # move to beginning of file if ( ! defined $ret ) { die "O06. sysseek failed: $!"; } $ret = sysread ( $indexdb, my $ni, length($i) ); if ( $ni != $i ) { die "O07. |$ni|$i| $!"; } } return 0; } ################################################################# sub init_m(){ my $segment_hbytes = shift; # Allocate a shared memory segment. my $segment_id = shmget (IPC_PRIVATE, $segment_hbytes, IPC_CREAT | IPC_EXCL | S_IRUSR | S_IWUSR); # Verify the segment's size. my $shmbuffer = ''; shmctl ($segment_id, IPC_STAT, $shmbuffer); my @mdata = unpack("i*",$shmbuffer); #not sure if that is right unpack? works :-) return($segment_id, $mdata[9] ); } sub write_m() { # Write a string to the shared memory segment. my $message = shift; shmwrite($segment_id, $message, 0, $segment_size) || die "$!"; #the 0, $segment_size can be broke up into substrings like 0,60 # or 61,195, etc return 0; } sub close_m(){ # Deallocate the shared memory segment. shmctl ($segment_id, IPC_RMID, 0); return 0; } 1; __END__