Properly support the ru_maxrss field of the rusage structure returned by

getrusage().  This patch includes documentation both of the getrusage()

implementation in general and of the ru_maxrss implementation

specifically.  This implementation matches that of FreeBSD, which is the

only other OS of which I'm aware that implements this field.
Like a number of other folks, we recently had a need for a non-/proc way

of getting the RSS of a process and happened on getrusage().  Unlike the

rest, though, we fixed the system call to do what we want.  I wrote a

wrong implementation and submitted it while I was sick; this time I took

my time and I think I got it right.
A test program that has been run against a number of systems (of which

only FreeBSD and Linux 2.6 with this patch applied passed) is also

available at

	http://www.exit.com/Archives/Linux/
Signed-off-by:  Frank Mayhar <fmayhar@google.com>
---

diff --git a/include/linux/sched.h b/include/linux/sched.h

index 3de7901..85735af 100644

--- a/include/linux/sched.h

+++ b/include/linux/sched.h

@@ -518,6 +518,7 @@ struct signal_struct {

 	unsigned long nvcsw, nivcsw, cnvcsw, cnivcsw;

 	unsigned long min_flt, maj_flt, cmin_flt, cmaj_flt;

 	unsigned long inblock, oublock, cinblock, coublock;

+	unsigned long cmaxrss;
 	/*

 	 * Cumulative ns of scheduled CPU time for dead threads in the

@@ -1027,6 +1028,8 @@ #endif

 	struct timespec real_start_time;	/* boot based time */

 /* mm fault and swap info: this can arguably be seen as either mm-specific or thread-specific */

 	unsigned long min_flt, maj_flt;

+/* maxrss gets the hiwater_rss in do_exit() */

+	unsigned long maxrss;
   	cputime_t it_prof_expires, it_virt_expires;

 	unsigned long long it_sched_expires;

diff --git a/kernel/exit.c b/kernel/exit.c

index 06b24b3..390d834 100644

--- a/kernel/exit.c

+++ b/kernel/exit.c

@@ -127,6 +127,8 @@ static void __exit_signal(struct task_st

 		sig->inblock += task_io_get_inblock(tsk);

 		sig->oublock += task_io_get_oublock...
[ message continues ]

Nice patch, but the Vaio always wins ;)
It boots OK, but when I ssh into the machine:
[   56.310698] sonypi: ioport 0x1080 busy, using sony-laptop? if not use check_ioport=0

[   56.314186] sonypi: failed to request ioports

[   56.317362] sonypi: probe of sonypi failed with error -16

[   57.017983] ipw2200: Radio Frequency Kill Switch is On:

[   57.017985] Kill switch must be turned off for wireless networking to work.

[   57.124331] ipw2200: Failed to send WEP_KEY: Aborted due to RF kill switch.

[   57.242396] ipw2200: Failed to send WEP_KEY: Command timed out.

[   60.343396] BUG: unable to handle kernel NULL pointer dereference at virtual address 0000009c

[   60.343573] printing eip: c012ba9c *pde = 00000000

[   60.343680] Oops: 0000 [#1] PREEMPT

[   60.343763] last sysfs file: /devices/system/cpu/cpu0/cpufreq/scaling_setspeed

[   60.343894] Modules linked in: ipw2200 sonypi ipv6 autofs4 hidp l2cap bluetooth sunrpc nf_conntrack_netbios_ns ipt_REJECT nf_conntrack_ipv4 xt_state nf_conntrack nfnetlink xt_tcpudp iptable_filter ip_tables x_tables acpi_cpufreq sbs sbshc nvram ohci1394 ieee1394 ehci_hcd uhci_hcd sg joydev snd_hda_intel snd_seq_dummy snd_seq_oss snd_seq_midi_event snd_seq snd_seq_device snd_pcm_oss snd_mixer_oss ieee80211 sr_mod cdrom snd_pcm ieee80211_crypt snd_timer i2c_i801 i2c_core snd pcspkr soundcore piix snd_page_alloc battery button ac generic ext3 jbd ide_disk ide_core

[   60.345225]

[   60.345258] Pid: 2503, comm: zsh Not tainted (2.6.23-rc7-mm1 #9)

[   60.345367] EIP: 0060:[<c012ba9c>] EFLAGS: 00010046 CPU: 0

[   60.345472] EIP is at getrusage+0x181/0x21f

[   60.345551] EAX: 00000000 EBX: 00000000 ECX: c2370ec0 EDX: 00000000

[   60.345665] ESI: c2370ec0 EDI: 00000002 EBP: c3cc3f1c ESP: c3cc3ec0

[   60.345779]  DS: 007b ES: 007b FS: 0000 GS: 0033 SS: 0068

[   60.345878] Process zsh (pid: 2503, ti=c3cc2000 task=c3cc0e00 task.ti=c3cc2000)

[   60.346009] last branch before last exception/interrupt

[   60.346112]  from c012ba9c (getrusage+0x181/0x21f)

[   60....
[ message continues ]

Acked-by: Rik van Riel <riel@redhat.com>
--

All Rights Reversed

-