Re: [PHP-DEV] Flex never-interactive mode

On Wed, 26 Feb 2003, Andi Gutmans wrote:

> At 12:48 PM 2/26/2003 -0800, Rasmus Lerdorf wrote:
> >I think we can add "%option never-interactive" to the ini-scanner lexer to
> >speed it up a tiny little bit.  Speeding up the ini scanner might be
> >important for the folks running the cgi version.  More importantly, to me
> >anyway, when we know we are not interactive, should we not
> >programmatically set is_interactive to false for the language scanner as
> >well?  I did this here and the ioctl syscalls that come from the isatty()
> >calls in the lexer dropped away speeding things up nicely.
> 
> Do you have any figures? (req/s wise)
> I think we can set it to false when we know we're not interactive. It 
> shouldn't be a problem.

Not really.  I've hacked and slashed a bunch of things and this is just
one of them.  I could pull out just this change and try to time it, I
guess.  But it can't help but be faster just by looking at the syscall
profiles before and after the change.  On a simple Hello World script
before the change you have this: (PHP 4.2 with realpath turned off)

 83757 apache  0.000010 CALL  __getcwd(0x9fbfe674,0xfff)
 83757 apache  0.000010 RET   __getcwd 0
 83757 apache  0.000010 CALL  chdir(0x9fbfe614)
 83757 apache  0.000030 RET   chdir 0
 83757 apache  0.000023 CALL  open(0x167588,0,0x1b6)
 83757 apache  0.000031 RET   open 5
 83757 apache  0.000009 CALL  __getcwd(0x9fbfdc14,0x400)
 83757 apache  0.000032 RET   __getcwd 0
 83757 apache  0.000031 CALL  ioctl(0x5,TIOCGETA,0x9fbfe4e4)
 83757 apache  0.000010 RET   ioctl -1 errno 25 Inappropriate ioctl for device
 83757 apache  0.000034 CALL  fstat(0x5,0x9fbfd42c)
 83757 apache  0.000010 RET   fstat 0
 83757 apache  0.000008 CALL  read(0x5,0x148000,0x2000)
 83757 apache  0.000023 RET   read 42/0x2a
 83757 apache  0.000008 CALL  read(0x5,0x148000,0x2000)
 83757 apache  0.000013 RET   read 0
 83757 apache  0.000046 CALL  ioctl(0x5,TIOCGETA,0x9fbfd4c0)
 83757 apache  0.000009 RET   ioctl -1 errno 25 Inappropriate ioctl for device
 83757 apache  0.000020 CALL  close(0x5)
 83757 apache  0.000010 RET   close 0
 83757 apache  0.000053 CALL  setitimer(0,0x9fbfe29c,0x9fbfe28c)
 83757 apache  0.000014 RET   setitimer 0
 83757 apache  0.000059 CALL  setitimer(0,0x9fbfe29c,0x9fbfe28c)
 83757 apache  0.000009 RET   setitimer 0
 83757 apache  0.000026 CALL  chdir(0x9fbfe674)
 83757 apache  0.000030 RET   chdir 0

The 3rd column there is the time it took for the call.  A failed ioctl is
one of the heavier syscalls and both of the ioctls disappear for this
request when you turn off is_interactive.  The ioctls are the same in 4.3.  
Here is what I am currently down to in 4.3.  I still need to get rid of 
that one lseek and am hoping to nuke the fstat as well.  I also need to 
figure out why setitimer is being called more in 4.3 than it was in 4.2.

 88046 apache  0.000009 CALL  __getcwd(0x9fbfe654,0xfff)
 88046 apache  0.000013 RET   __getcwd 0
 88046 apache  0.000009 CALL  chdir(0x9fbfe5f4)
 88046 apache  0.000032 RET   chdir 0
 88046 apache  0.000010 CALL  setitimer(0x2,0x9fbfe63c,0)
 88046 apache  0.000008 RET   setitimer 0
 88046 apache  0.000008 CALL  setitimer(0x2,0x9fbfe61c,0)
 88046 apache  0.000006 RET   setitimer 0
 88046 apache  0.000028 CALL  sigaction(0x1b,0x9fbfe5b4,0x9fbfe59c)
 88046 apache  0.000008 RET   sigaction 0
 88046 apache  0.000007 CALL  sigprocmask(0x2,0x9fbfe60c,0)
 88046 apache  0.000006 RET   sigprocmask 0
 88046 apache  0.000030 CALL  open(0x12ce0c,0,0x1b6)
 88046 apache  0.000033 RET   open 5
 88046 apache  0.000021 CALL  lseek(0x5,0,0,0,0)
 88046 apache  0.000008 RET   lseek 0
 88046 apache  0.000043 CALL  fstat(0x5,0x9fbfd40c)
 88046 apache  0.000013 RET   fstat 0
 88046 apache  0.000009 CALL  read(0x5,0x13f000,0x2000)
 88046 apache  0.000022 RET   read 42/0x2a
 88046 apache  0.000006 CALL  read(0x5,0x13f000,0x2000)
 88046 apache  0.000015 RET   read 0
 88046 apache  0.000066 CALL  close(0x5)
 88046 apache  0.000015 RET   close 0
 88046 apache  0.000047 CALL  setitimer(0,0x9fbfdf7c,0x9fbfdf6c)
 88046 apache  0.000012 RET   setitimer 0
 88046 apache  0.000043 CALL  setitimer(0,0x9fbfdf7c,0x9fbfdf6c)
 88046 apache  0.000009 RET   setitimer 0
 88046 apache  0.000021 CALL  chdir(0x9fbfe654)
 88046 apache  0.000031 RET   chdir 0

-Rasmus