Memory Usage Stats

[Jeremy Chadwick]

----- Forwarded message from Sabeeh Baig <baigsabeeh at gmail.com> -----

> From: Sabeeh Baig <baigsabeeh at gmail.com>
> To: Jeremy Chadwick <koitsu at freebsd.org>
> Date: Thu, 21 Aug 2008 16:51:13 -0400
> Subject: Re: Memory Usage Stats
> 
> 1)  I didn't know that about swap allocation.
> 
> 2)  I know what each of the categories of memory stand for and what
> role they play and how they are used, so no I don't think of free
> memory like that.  Actually, total free memory includes inactive as
> well, since inactive keeps inactive pages for future use to improve
> performance, but dynamically reallocates them if necessary.
> 
> 3)  I followed standard update procedure listed in the handbook.  I
> don't deviate from that, as I don't want a broken mess to deal with.
> 
> ------------------------------------------------------------------------------
> 
> 1)  I run AMD64.
> 
> 2)  How would I get this information, as I rebuilt it over a week ago.
> 
> 3)  I will provide this information once I get home.
> 
> On Thu, Aug 21, 2008 at 4:16 PM, Jeremy Chadwick <koitsu at freebsd.org> wrote:
> > On Thu, Aug 21, 2008 at 02:05:50PM -0400, Sabeeh Baig wrote:
> >> I've been noticing never-before-seen highs in memory usage, since the
> >> last time I rebuilt world a bout a week ago.  I have 2GB of memory and
> >> 2GB of swap space.  According to top, a little over 1GB of memory is
> >> active, 70MB free, 300MB wired, and the rest inactive.  I also have
> >> 59MB of swap used.
> >
> > The swap in use is fine; memory which is often untouched (e.g. allocated
> > but then not utilised for some time) is often swapped out to disk.
> >
> >> If I close an application, the amount of active memory never decreases
> >> and the other stats don't change either.
> >
> > I think you may be reading top output incorrectly, which is a common
> > problem these days.  I hope you're not assuming that the "Free" column
> > in top defines how much memory there is available for allocation on the
> > system.
> >
> >> The active figure can't be right even now, as I only have
> >> Xfce, Xorg, screen, two zsh session, slurm, irssi, pidgin, mpd, ncmpc,
> >> and irssi running.  That's usually my normal session and usage has
> >> been better before I recompiled.
> >
> >> Is it possible that top is displaying the wrong stats?
> >
> > Possibly -- how exactly did you rebuild your system when you said you
> > "rebuilt world"?  Did you follow each and every step in src/Makefile,
> > including booting into single user, etc. etc.?
> >
> > The reason I mention this is, lots of userland utilities rely on libkvm.
> > For example, you rebuilt your kernel (and the KVM structure within the
> > kernel changed due to CVS commits or whatever else), but you didn't
> > rebuild userland (e.g. libkvm still refers to the old KVM structure),
> > then you will see very odd numbers or possibly total breakage in top,
> > ps, systat, etc...
> >
> >> Is there any other utility I could try?
> >
> > systat, vmstat, and procstat (the latter only available if you're using
> > a fairly recent RELENG_7 or HEAD; and it may not be of much help here,
> > since it just provides a break-down of memory usage within a process)
> >
> >> I've tried ps auxm, but that's not exactly what I'm looking for.
> >
> > You could start by:
> >
> > 1) Stating if you're on i386 or amd64 -- it matters,
> > 2) Providing top output (sorted by "res") before and after said
> >   rebuild,
> > 3) Providing top output (sorted by "res") before and after you
> >   terminate a process that uses a large amount of memory.
> >
> > --
> > | Jeremy Chadwick                                jdc at parodius.com |
> > | Parodius Networking                       http://www.parodius.com/ |
> > | UNIX Systems Administrator                  Mountain View, CA, USA |
> > | Making life hard for others since 1977.              PGP: 4BD6C0CB |
> >
> >
> 
> 
> 
> -- 
> "UNIX is basically a simple operating system, but you have to be a
> genius to understand the simplicity."
> 
> Sabeeh Ahmed Baig
> 

----- End forwarded message -----

OP forgot to CC the mailing list.

-- 
| Jeremy Chadwick                                jdc at parodius.com |
| Parodius Networking                       http://www.parodius.com/ |
| UNIX Systems Administrator                  Mountain View, CA, USA |
| Making life hard for others since 1977.              PGP: 4BD6C0CB |