Re: Memory leak in 2.4.33-pre1?

From: Yoss
Date: Wed Feb 15 2006 - 03:59:30 EST


On Tue, Feb 14, 2006 at 10:43:49PM +0100, Willy TARREAU wrote:
> On Tue, Feb 14, 2006 at 09:21:36AM +0100, Yoss wrote:
> > I downgraded hernel to 2.4.33 last night.
> I presume you mean 2.4.32 here.

Right. :)

>
> > So there is no slabinfo from that problem now. But thank you for reply.
> > Why is this memory not showed somewhere in top or free?
>
> I don't know, it's some gray area for me too, it's just that I'm used to
> this behaviour. I even have a program that I run to free it when I want
> to prioritize disk cache usage over dentry cache (appended to this mail).

I think it is grey for me too ;\
After about 36h of run the summary size of processes is 714MB. Free
says:

webcache:~# free -m
total used free shared buffers cached
Mem: 1009 996 13 0 50 93
-/+ buffers/cache: 852 157
Swap: 1953 0 1953

So thereis 139MB of difference. But:

#slabtop -s c -o | head -20

Active / Total Objects (% used) : 793971 / 805664 (98.5%)
Active / Total Slabs (% used) : 66499 / 66513 (100.0%)
Active / Total Caches (% used) : 36 / 59 (61.0%)
Active / Total Size (% used) : 235510.62K / 236644.88K (99.5%)
Minimum / Average / Maximum Object : 0.02K / 0.29K / 128.00K

OBJS ACTIVE USE OBJ SIZE SLABS OBJ/SLAB CACHE SIZE NAME
362495 362490 99% 0.50K 51785 8 207140K inode_cache
380910 380900 99% 0.12K 12697 32 50788K dentry_cache
44800 35342 78% 0.09K 1120 42 4480K buffer_head
636 607 95% 2.00K 318 2 1272K size-2048
139 139 100% 4.00K 139 1 556K size-4096
2064 1891 91% 0.16K 86 25 344K ip_dst_cache
232 224 96% 0.91K 58 4 232K sock
2080 2048 98% 0.09K 52 42 208K blkdev_requests
5198 4495 86% 0.03K 46 128 184K size-32
1032 658 63% 0.16K 43 25 172K skbuff_head_cache
870 864 99% 0.12K 29 32 116K filp
1416 1381 97% 0.06K 24 64 96K size-64
570 545 95% 0.12K 19 32 76K size-128

> Have you noticed the difference ? So the memory is not wasted at all. It's
> just reported as 'used'.

I see. I also noticed that I simply cannot tell what for is this memory
used. Is this better for me to enlarge cache_mem in squid for about
100MB and have less *_cache or is better to have more *_cache? :)

> > > If you don't believe me, simply allocate 1 GB in a process, then free it.
> > If that what you said is rigth, day after tomorow I'll have the same
> > situation - only thing I have changed is kernel. So we'll see. :)
>
> If you encounter it, simply run the tool below with a size in kB. Warning!
> a wrong parameter associated with improper ulimit will hang your system !
> Ask it to allocate what you *know* you can free (eg: the swapfree space).

I don't matter is this memory used for cache or free. I just want to be
sure that it is not leaking :)

--
Bartłomiej Butyn aka Yoss
Nie ma tego złego co by na gorsze nie wyszło.
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