(hopefully plain text this time)
Hi,
I'm seeing a constant leak in size-4096 on a machine running 2.4.20-18 SMP
BIGMEM, which might / might not be related to the machine finally going out
of memory and going into a hang.
I saw a discussion around similar problems in 2.6.0 (2.6.0-test5/6 (and
probably 7 too) size-4096 memory leak - http://lkml.org/lkml/2003/10/17/5 )
and an ext3 patch was suggested by Andrew Morton.
>From a brief look the code in 2.4 it seems like the patch might be relevant
here as well. Is the size-4096 leak a known issue for 2.4 ?
Is the 2.6 patch applicable in 2.4 as well ?
Thanks,
--
Yuval Yeret
Yuval at exanet dot com
Exanet
http://www.exanet.com
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Hi Yuval, hi list,
> I'm seeing a constant leak in size-4096 on a machine running
> 2.4.20-18 SMP BIGMEM, which might / might not be related to the
> machine finally going out of memory and going into a hang.
I just wanted to let you know that I have been experiencing similar
leaks. So far, I wasn't enable to find where the leak was, but your
theory matches my observations:
1* On two systems running 2.4.20-2.4.22 kernels, I observed that the
free memory as reported by top was going down regularly, by blocks of 4
or 8kB at an average rate of 90kB/min. Sometimes the value would
stabilize, but I couldn't understand why. What was lost as "free"
memory
increased "buffers" from the same amount. Still that value doesn't
exceed a few dozen MB and sometimes goes does by large blocks, so I was
wondering if there was a real leak or if it was just some kind of
regular prebuffering.
2* On two other, seemingly similar systems, the memory leak wouldn't
occur. It happens that these two systems do *not* use ext3, while the
fisrt two *do* use ext3.
3* The leak isn't distribution specific. I experienced it on both a
Mandrake-shipped kernel and a self-compiled one on a Slackware system.
Your theory that it comes from the ext3 driver makes full sense. I'll
confirm that later today, by using ext2 only on one of the leaking
systems (without changing kernels of course).
The other leaking system is used as a development server. It used to
become very slow after several days. We are now restarting it every
monday and have no significant slowdown anymore. Having other things to
do, I stopped my experiments there, but could do some more now if it
can help.
--
Jean Delvare
http://www.ensicaen.ismra.fr/~delvare/
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Hi,
On Wed, 2003-11-26 at 10:57, Jean Delvare wrote:
> I just wanted to let you know that I have been experiencing similar
> leaks. So far, I wasn't enable to find where the leak was, but your
> theory matches my observations:
>
> 1* On two systems running 2.4.20-2.4.22 kernels, I observed that the
> free memory as reported by top was going down regularly, by blocks of 4
> or 8kB at an average rate of 90kB/min. Sometimes the value would
> stabilize, but I couldn't understand why. What was lost as "free"
> memory
> increased "buffers" from the same amount.
That's not a leak, it simply sounds like cache effects. atime updates
result in journal commits under ext3, and those use at least a couple of
buffers at a time (one for the metadata descriptor block in the journal,
one for the journal commit.) Those aren't leaks --- they are temporary
use of cache, and once the IO has complete the memory can be immediately
reclaimed by the kernel if it is needed for anything else.
Cheers,
Stephen
>From: "Stephen C. Tweedie" <[email protected]>
>
>That's not a leak, it simply sounds like cache effects. atime updates
>result in journal commits under ext3, and those use at least a couple of
>buffers at a time (one for the metadata descriptor block in the journal,
>one for the journal commit.) Those aren't leaks --- they are temporary
>use of cache, and once the IO has complete the memory can be immediately
>reclaimed by the kernel if it is needed for anything else.
I'm using noatime for my ext3 mount points ...
>
>Cheers,
> Stephen
>
>
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