On 02/03/2010 04:57 AM, Torsten Förtsch wrote:
> Well, I tend to disagree. (Fred, Adam please read on.)
Okay. Have you looked at the actual output of test.cgi?
Here's an example of these values just on my local machine, for my bash
interpreter:
[mka...@es-compy ~]$ cat /proc/self/statm
21045 125 107 13 0 65 0
[mka...@es-compy ~]$ cat /proc/self/status | grep Vm
VmPeak: 84180 kB
VmSize: 84180 kB
VmLck: 0 kB
VmHWM: 496 kB
VmRSS: 496 kB
VmData: 176 kB
VmStk: 84 kB
VmExe: 52 kB
VmLib: 1548 kB
VmPTE: 48 kB
Would you consider that bash is taking up 84MB, or would you consider
it's taking up 496KB? I have 2GB in physical RAM and 2GB in swap. So,
theoretically, I should only be able to open 48 terminals before I OOM.
With 60 terminals open, here's the result of "free":
total used free
Mem: 1990 1855 134
-/+ buffers/cache: 1140 850
Swap: 1999 212 1787
If I were simply to add up the "Virt" column of the top 15 processes in
"top" on my machine, I'd be using somewhere in the vicinity of 20GB of RAM.
> So, either the far older statm technique is also wrong or the patch is wrong.
I would suspect that if you're using column 0 as the size, then statm
is also indeed wrong.
> =item * Apache2::SizeLimit->set_max_process_size($size)
>
> This sets the maximum size of the process, including both shared and
> unshared memory.
Ahh, but look at the output of both the "shared" and "private"
accessors, and they do not add up to VmSize. They add up to RSS.
> Perhaps Apache2::SizeLimit::Core should read:
>
> sub _check_size {
> my $class = shift;
>
> my ($size, $share, $unshared) = $class->_platform_check_size();
>
> return ($size, $share, defined $unshared ? $unshared : $size - $share);
That would certainly help (because then you would get a more accurate
count of the current private RSS), although I'd argue that VmSize is
still meaningless. I can imagine few instances where you'd want to know
the total size of the address space of a process, even if most of it had
never been mapped to an actual memory page.
-Max
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