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<  Erlang patches mailing list  ~  lots of uname syscalls on boot - patch
davidw at dedasys.com (Da
Posted: Mon May 03, 2004 10:08 am Reply with quote
Guest
[ Please CC replies to me. ]

Hi,

I'm pretty new to Erlang, so maybe there is a good reason for this
behavior, but I noticed that when starting up, erlang calls uname (2)
a lot:

davidw_at_coosbay:~$ strace -o output erl ./hw.erl -noinput -s hw main
hello world
davidw_at_coosbay:~$ grep -c uname output
982

I had a go at reducing that in ./erts/emulator/sys/unix/sys.c:

void
os_flavor(char* namebuf, /* Where to return the name. */
unsigned size) /* Size of name buffer. */
{
static int called = 0;
static struct utsname uts; /* Information about the system. */

if (called != 1) {
(void) uname(&uts);
called = 1;
}
strcpy(namebuf, uts.sysname);
for ( ; *namebuf; namebuf++)
if (isupper((int) *namebuf))
*namebuf = tolower((int) *namebuf);
}

This change drammatically reduces the amount of uname syscalls:

davidw_at_coosbay:~$ strace -o output /home/davidw/download/erlang-9.2/bin/erl ./hw.erl -noinput -s hw main
hello world
davidw_at_coosbay:~$ grep -c uname output
6

It's not that big a deal I guess, but I suppose it speeds things up
just a bit.

Thankyou,
--
David N. Welton
Consulting: http://www.dedasys.com/
Personal: http://www.dedasys.com/davidw/
Free Software: http://www.dedasys.com/freesoftware/
Apache Tcl: http://tcl.apache.org/


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