kernel_optimize_test/kernel
Hugh Dickins 365e9c87a9 [PATCH] mm: update_hiwaters just in time
update_mem_hiwater has attracted various criticisms, in particular from those
concerned with mm scalability.  Originally it was called whenever rss or
total_vm got raised.  Then many of those callsites were replaced by a timer
tick call from account_system_time.  Now Frank van Maarseveen reports that to
be found inadequate.  How about this?  Works for Frank.

Replace update_mem_hiwater, a poor combination of two unrelated ops, by macros
update_hiwater_rss and update_hiwater_vm.  Don't attempt to keep
mm->hiwater_rss up to date at timer tick, nor every time we raise rss (usually
by 1): those are hot paths.  Do the opposite, update only when about to lower
rss (usually by many), or just before final accounting in do_exit.  Handle
mm->hiwater_vm in the same way, though it's much less of an issue.  Demand
that whoever collects these hiwater statistics do the work of taking the
maximum with rss or total_vm.

And there has been no collector of these hiwater statistics in the tree.  The
new convention needs an example, so match Frank's usage by adding a VmPeak
line above VmSize to /proc/<pid>/status, and also a VmHWM line above VmRSS
(High-Water-Mark or High-Water-Memory).

There was a particular anomaly during mremap move, that hiwater_vm might be
captured too high.  A fleeting such anomaly remains, but it's quickly
corrected now, whereas before it would stick.

What locking?  None: if the app is racy then these statistics will be racy,
it's not worth any overhead to make them exact.  But whenever it suits,
hiwater_vm is updated under exclusive mmap_sem, and hiwater_rss under
page_table_lock (for now) or with preemption disabled (later on): without
going to any trouble, minimize the time between reading current values and
updating, to minimize those occasions when a racing thread bumps a count up
and back down in between.

Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29 21:40:39 -07:00
..
irq [PATCH] CHECK_IRQ_PER_CPU() to avoid dead code in __do_IRQ() 2005-09-07 16:57:29 -07:00
power [PATCH] core remove PageReserved 2005-10-29 21:40:39 -07:00
acct.c [PATCH] mm: rss = file_rss + anon_rss 2005-10-29 21:40:38 -07:00
audit.c [PATCH] gfp_t: kernel/* 2005-10-28 08:16:49 -07:00
auditsc.c [PATCH] gfp_t: kernel/* 2005-10-28 08:16:49 -07:00
capability.c [PATCH] kernel/capability.c: add kerneldoc 2005-07-27 16:26:06 -07:00
compat.c [PATCH] kernel: fix-up schedule_timeout() usage 2005-09-10 10:06:37 -07:00
configs.c Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
cpu.c [PATCH] i386 CPU hotplug 2005-06-25 16:24:29 -07:00
cpuset.c [PATCH] gfp flags annotations - part 1 2005-10-08 15:00:57 -07:00
crash_dump.c [PATCH] kernel/crash_dump.c: add kerneldoc 2005-07-27 16:26:06 -07:00
dma.c Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
exec_domain.c Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
exit.c [PATCH] mm: update_hiwaters just in time 2005-10-29 21:40:39 -07:00
extable.c Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
fork.c [PATCH] mm: dup_mmap down new mmap_sem 2005-10-29 21:40:38 -07:00
futex.c [PATCH] futex: remove duplicate code 2005-09-07 16:57:33 -07:00
intermodule.c [PATCH] introduce and use kzalloc 2005-09-07 16:57:45 -07:00
itimer.c [PATCH] itimer fixes 2005-07-27 16:25:51 -07:00
kallsyms.c [PATCH] ppc32: platform-specific functions missing from kallsyms. 2005-05-05 16:36:31 -07:00
Kconfig.hz [PATCH] i386: Selectable Frequency of the Timer Interrupt 2005-06-23 09:45:10 -07:00
Kconfig.preempt [PATCH] sched: voluntary kernel preemption 2005-06-25 16:24:45 -07:00
kexec.c [PATCH] gfp_t: kernel/* 2005-10-28 08:16:49 -07:00
kfifo.c [PATCH] gfp flags annotations - part 1 2005-10-08 15:00:57 -07:00
kmod.c [PATCH] Keys: Pass session keyring to call_usermodehelper() 2005-06-24 00:05:18 -07:00
kprobes.c [PATCH] kprobes: fix bug when probed on task and isr functions 2005-09-07 16:58:01 -07:00
ksysfs.c [PATCH] Kdump: Export crash notes section address through sysfs 2005-06-25 16:24:51 -07:00
kthread.c [PATCH] use smp_mb/wmb/rmb where possible 2005-05-01 08:58:47 -07:00
Makefile [PATCH] spinlock consolidation 2005-09-10 10:06:21 -07:00
module.c [PATCH] use add_taint() for setting tainted bit flags 2005-09-13 08:22:29 -07:00
panic.c [PATCH] Call emergency_reboot from panic 2005-07-26 14:35:43 -07:00
params.c [PATCH] Ignore trailing whitespace on kernel parameters correctly 2005-09-28 07:46:41 -07:00
pid.c Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
posix-cpu-timers.c [PATCH] Yet more posix-cpu-timer fixes 2005-10-27 09:08:43 -07:00
posix-timers.c [PATCH] Call exit_itimers from do_exit, not __exit_signal 2005-10-21 15:38:08 -07:00
printk.c [PATCH] Add printk_clock() 2005-09-21 10:11:54 -07:00
profile.c [PATCH] mostly_read data section 2005-07-07 18:23:46 -07:00
ptrace.c [PATCH] remove duplicated code from proc and ptrace 2005-09-07 16:57:43 -07:00
rcupdate.c [PATCH] rcu: keep rcu callback event counter 2005-10-17 15:27:58 -07:00
resource.c [PATCH] introduce and use kzalloc 2005-09-07 16:57:45 -07:00
sched.c [PATCH] mm: update_hiwaters just in time 2005-10-29 21:40:39 -07:00
seccomp.c Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
signal.c [PATCH] fix ->signal->live leak in copy_process() 2005-10-29 10:28:13 -07:00
softirq.c [PATCH] x86-64: Some cleanup and optimization to the processor data area. 2005-09-12 10:49:58 -07:00
softlockup.c [PATCH] detect soft lockups 2005-09-07 16:57:17 -07:00
spinlock.c [PATCH] spinlock consolidation 2005-09-10 10:06:21 -07:00
stop_machine.c [PATCH] smp_processor_id() cleanup 2005-06-21 18:46:13 -07:00
sys_ni.c [PATCH] remove sys_set_zone_reclaim() 2005-08-01 10:03:56 -07:00
sys.c [PATCH] reboot: comment and factor the main reboot functions 2005-09-22 22:17:33 -07:00
sysctl.c [NET]: Fix sparse warnings 2005-08-29 16:01:32 -07:00
time.c [PATCH] missing exports of do_settimeofday() variants 2005-10-29 10:35:07 -07:00
timer.c [PATCH] TIMERS: add missing compensation for HZ == 250 2005-10-29 21:40:35 -07:00
uid16.c Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
user.c [PATCH] inotify 2005-07-12 20:38:38 -07:00
wait.c Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
workqueue.c [PATCH] introduce and use kzalloc 2005-09-07 16:57:45 -07:00