Summer

Here comes summer, a season of departures, when the Welly lads are setting out for Hong Kong and New York; and a start of adventures, when two dear friends have just got married and are leaving Beijing for the South. Wish you all good luck!

Congrats to Zhenyu

... who has successfully and completely turned into a family man!

It seems that everyone is getting married in 2009...

maxrss

The ru_maxrss field in struct rusage provides a convenient way to measure peak memory usage of a program (via getrusage, wait4, or simply `/usr/bin/time -p') on BSD systems, including Mac OS X. According the man page, ru_maxrss represents `the maximum resident set size utilized (in kilobytes)'.

Let's try it on Mac OS X (Leopard, 10.5.6).
$ /usr/bin/time -l uname -v
Darwin Kernel Version 9.6.0: Mon Nov 24 17:37:00 PST 2008; root:xnu-1228.9.59~1/RELEASE_I386
0.00 real 0.00 user 0.00 sys
385024 maximum resident set size
...

Do you really think the simple `uname' could take 385,024 KB (376 MB) memory ? It also reports 282624 maxrss for a small C program that only contains an empty main and is compiled by `gcc -O2'.

Here is a comparison.

FreeBSD 7.1, kern_clock.c

 527 rss = pgtok(vmspace_resident_count(vm));
 528 if (ru->ru_maxrss < rss)
 529   ru->ru_maxrss = rss;

Note pgtok is often defined as follows.
#define pgtok(x) ((unsigned long)(x) * (PAGE_SIZE / 1024))

Mac OS X 10.5.6, kern_exit.c

 612 p->p_ru->ru_maxrss = tinfo.resident_size;

task.c

1205 if (flavor == TASK_BASIC2_INFO_32) {
       ...
1210   basic_info->resident_size = pmap_resident_max(...);
1211 } else {
1212   basic_info->resident_size = pmap_resident_count(...);
1213 }
1214 basic_info->resident_size *= PAGE_SIZE;

Does Apple forget `/ 1024' or something? Hope Linux would not give a strange number.