Re: [PATCH 2.6.14-rc2] fix incorrect mm->hiwater_vm and mm->hiwater_rss

[Frank van Maarseveen <frankvm@frankvm.com>]

On Wed, Sep 21, 2005 at 03:38:57PM +0100, Hugh Dickins wrote:
> On Wed, 21 Sep 2005, Frank van Maarseveen wrote:
> > This fixes a post 2.6.11 regression in maintaining the mm->hiwater_* counters.
> 
> It would be a good idea to CC Christoph Lameter, who I believe was the
> one who very intentionally moved most of these updates out to timer tick.
> Is that significantly missing updates?

Apparently: I use a private patch (see below) to expose mm->hiwater_vm
to userland via /proc to detect misbehaving processes and for measuring
worst case memory use by programs. from 2.6.12 on I'm constantly seeing
a lot of processes with hiwater_vm < total_vm.

> 2. You've missed the instance Dave Miller recently added in fs/compat.c.

Thanks. I'll add that.

> 
> 3. If these are to be peppered back all over, then the places where
>    total_vm changes and the places where rss changes are almost completely
>    disjoint, so it's lazy to be calling one function to do both all over.

I'll look into this.

> 
> 5. Please add appropriate CONFIG, dummy macros etc., so that no time
>    is wasted on these updates in all the vanilla systems which have no
>    interest in them - but maybe Christoph already has that well in hand.

I'm not sure where it's being used for, other than how I use it in which
case it probably should depend on CONFIG_PROC_FS:

--- ./fs/proc/task_mmu.c.orig	2005-07-07 14:22:12.000000000 +0200
+++ ./fs/proc/task_mmu.c	2005-09-16 13:51:56.000000000 +0200
@@ -14,6 +14,7 @@
 	text = (PAGE_ALIGN(mm->end_code) - (mm->start_code & PAGE_MASK)) >> 10;
 	lib = (mm->exec_vm << (PAGE_SHIFT-10)) - text;
 	buffer += sprintf(buffer,
+		"VmPeak:\t%8lu kB\n"
 		"VmSize:\t%8lu kB\n"
 		"VmLck:\t%8lu kB\n"
 		"VmRSS:\t%8lu kB\n"
@@ -22,6 +23,7 @@
 		"VmExe:\t%8lu kB\n"
 		"VmLib:\t%8lu kB\n"
 		"VmPTE:\t%8lu kB\n",
+		mm->hiwater_vm << (PAGE_SHIFT-10),
 		(mm->total_vm - mm->reserved_vm) << (PAGE_SHIFT-10),
 		mm->locked_vm << (PAGE_SHIFT-10),
 		get_mm_counter(mm, rss) << (PAGE_SHIFT-10),


-- 
Frank
-
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