On Aug 26 2007 12:49, Fred Tyler wrote:
>>
>> So I guess you are not seeing any memory leak at all, but just the regular
>> caching?
>
>I certainly hope that is the case, but until I try it on the
>production machine tonight I won't know for sure.
Note that not all kernels have the 'drop_caches' control file.
So there is not much you can do there.
>If this is indeed a
>leak, it's pretty slow, and it takes a week or so before you can even
>start noticing it on the graphs
Well if it helps, you can accelerate the 'problem', by issuing, for example:
(1)
dd_rescue /dev/sda /dev/null -m $[4*1048576*1024]
for reading 4 GB from disk straight and populating 'buffers'.
(2)
cat /some/big/big/big/file >/dev/null
for reading X GB from disk and populating 'cache'.
and then you'll see. Also note that a kernel leak will eventually lead
to very low buffers/cached values (the ones to the far right) even when
large amounts of data are read (using either dd_rescue/cat as mentioned
above), because, of course, the leak clogs up memory.
total used free shared buffers cached
Mem: 775792 493724 282068 0 8 308416
-/+ buffers/cache: 185300 590492
Swap: 795136 60 795076
>I can say with absolute certainty that something very similar was
>happening in 2.6.12 (compare the graphs in my original email), and in
>2.6.12 it would inevitably lead to the server running entirely out of
>memory, to the point where applications could no longer allocate
>memory and the server would have to be rebooted.
>The symptoms were almost identical in that case: I'd shut down
>virtually every application on the server, but the memory would still
>be almost entirely in use. I understand there's kernel caching, but if
>the kernel caching occurs at the expense of any other applications
>being able to access memory, then there's a real problem. (I actually
>still have one 2.6.12 machine running, but drop_caches doesn't appear
>to exist on it so I can't test it there. Is there an analogue?)
If you see an Out Of Memory notice in dmesg, you'll know there is a
leak even if everything was shut down.
>
>Anyway, I'll post the results from the 2.6.20 server as soon as I have
>them. Should be late tonight.
>
>Thanks.
>
Jan
--
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[Index of Archives]
[Kernel Newbies]
[Netfilter]
[Bugtraq]
[Photo]
[Stuff]
[Gimp]
[Yosemite News]
[MIPS Linux]
[ARM Linux]
[Linux Security]
[Linux RAID]
[Video 4 Linux]
[Linux for the blind]
[Linux Resources]
