Re: [Xenomai-help] Error: cat: /proc/xenomai/stat: Cannot allocate memory

[Philippe Gerum <rpm@xenomai.org>]

On Sat, 2007-02-03 at 19:20 +0100, Dmitry Adamushko wrote:
> Hi,
> 
> are there any other memory pools increasing while "MemFree" is decreasing?
> 
> cat /proc/meminfo
> 
> If it's kmalloc() - related, I'd expect "Slab" to be increasing..  [1]
> 
> Moreover, if it's left to be running for quite some time, does it
> actually causes an "out-of-memory" problem in the end?  [2]
> 
> I have run "while true ; do cat /proc/interrupts; done" for some time
> and "MemFree" is going down but what's going up is "Buffers" +
> "Cached" (mainly, the first one) and not
> "Slab".
> 
> cat /proc/interrupts returns file content which is different every
> time and might be cached (likely - "Buffers").. Actually, do you
> observe similar behaviour when reading any other /proc file (or even
> any regular) ?
> 
> After all, Linux memory manager is quite dynamic in its behaviour, and
> "MemFree" does not really answer a question "how much memory is free"
> as there are some _reclaimable_ sources of memory ("buffers" and
> "cached")..
> 
> So what's about [1]? Of course, if you can encounter [2] after some time..
> 

Really, what I see here very much looks like a constant leakage on an
otherwise idle system, not some artefact from the mm; albeit the cached
mem seems stable, the free memory goes down irremediably. Not all /proc
entries seem to cause the issue, and the interesting thing is
that /proc/interrupts and /proc/xenomai/sched|stat all use the seqfile
support to output their data.

Anyway, I did not dig the issue enough code-wise to remove all the
conditionals from my wording, but there seems to be something wrong
somewhere, and that's not Xenomai related. Or, the Linux VM is seasoned
enough to try to make people think it loses memory albeit it doesn't.

-- 
Philippe.