Wrong Vmalloc numbers in /proc/meminfo

Wrong Vmalloc numbers in /proc/meminfo

[Frans Pop]

With 2.6.31 (on x86_64) I'm seeing the following in /proc/meminfo.

$ cat /proc/meminfo
MemTotal:        2030968 kB
MemFree:          539408 kB
Buffers:           94984 kB
Cached:           308564 kB
SwapCached:        16048 kB
Active:           652236 kB
Inactive:         428808 kB
Active(anon):     436808 kB
Inactive(anon):   246996 kB
Active(file):     215428 kB
Inactive(file):   181812 kB
Unevictable:        1632 kB
Mlocked:            1632 kB
SwapTotal:       2097144 kB
SwapFree:        1979524 kB
Dirty:                12 kB
Writeback:             0 kB
AnonPages:        671276 kB
Mapped:            57684 kB
Slab:             177692 kB
SReclaimable:     160516 kB
SUnreclaim:        17176 kB
PageTables:        14812 kB
NFS_Unstable:          0 kB
Bounce:                0 kB
WritebackTmp:          0 kB
CommitLimit:     3112628 kB
Committed_AS:     988780 kB
VmallocTotal:   34359738367 kB
VmallocUsed:      340084 kB
VmallocChunk:   34359387131 kB
DirectMap4k:     2008768 kB
DirectMap2M:       63488 kB

Is it me or are VmallocTotal and VmallocChunk off by a factor 10,000 or so?

Cheers,
FJP

Re: Wrong Vmalloc numbers in /proc/meminfo

[KAMEZAWA Hiroyuki]

On Mon, 28 Sep 2009 02:09:30 +0200
Frans Pop <elendil@planet.nl> wrote:

> With 2.6.31 (on x86_64) I'm seeing the following in /proc/meminfo.
> 
> $ cat /proc/meminfo
> MemTotal:        2030968 kB
> MemFree:          539408 kB
> Buffers:           94984 kB
> Cached:           308564 kB
> SwapCached:        16048 kB
> Active:           652236 kB
> Inactive:         428808 kB
> Active(anon):     436808 kB
> Inactive(anon):   246996 kB
> Active(file):     215428 kB
> Inactive(file):   181812 kB
> Unevictable:        1632 kB
> Mlocked:            1632 kB
> SwapTotal:       2097144 kB
> SwapFree:        1979524 kB
> Dirty:                12 kB
> Writeback:             0 kB
> AnonPages:        671276 kB
> Mapped:            57684 kB
> Slab:             177692 kB
> SReclaimable:     160516 kB
> SUnreclaim:        17176 kB
> PageTables:        14812 kB
> NFS_Unstable:          0 kB
> Bounce:                0 kB
> WritebackTmp:          0 kB
> CommitLimit:     3112628 kB
> Committed_AS:     988780 kB
> VmallocTotal:   34359738367 kB
> VmallocUsed:      340084 kB
> VmallocChunk:   34359387131 kB
> DirectMap4k:     2008768 kB
> DirectMap2M:       63488 kB
> 
> Is it me or are VmallocTotal and VmallocChunk off by a factor 10,000 or so?
> 
I'm sorry I misunderstand your 10,000 implies.

On my x86-64 box.
VmallocTotal:   34359738367 kB
VmallocUsed:      100856 kB
VmallocChunk:   34359583863 kB

Then,
34359738367 - 34359583863
154504

Then difference is 13412 (pages) 

Hmm. in /proc/vmallocinfo
==
..
0xffffc9000652b000-0xffffc9000672c000 2101248 sys_swapon+0x6a2/0xcd0 pages=512 vmalloc N0=512
0xffffc90007efd000-0xffffc90008dde000 15601664 pcpu_alloc+0x3ad/0x4e0 vmalloc
0xffffc900096d9000-0xffffc900096dd000   16384 e1000e_setup_tx_resources+0x39/0xe0 [e1000e] pages=3 vmalloc N0=3
0xffffc900096de000-0xffffc900096e2000   16384 e1000e_setup_rx_resources+0x37/0x160 [e1000e] pages=3 vmalloc N0=3
==

It seems some amount of memory holes (rather than PAGESIZE) between vmalloc area
info.(especially around pcpu_alloc..) please check /proc/vmallocinfo if you
feel something strange.


Thanks,
-Kame


> Cheers,
> FJP
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Re: Wrong Vmalloc numbers in /proc/meminfo

[Frans Pop]

On Monday 28 September 2009, KAMEZAWA Hiroyuki wrote:
> > VmallocTotal:   34359738367 kB
> > VmallocUsed:      340084 kB
> > VmallocChunk:   34359387131 kB
> >
> > Is it me or are VmallocTotal and VmallocChunk off by a factor 10,000
> > or so?
>
> I'm sorry I misunderstand your 10,000 implies.

What I meant is: is the Vmalloc area really 32 *terra*bytes in size?
Seems rather big for a system with only 2GB RAM.

I'd never noticed it before and it looks strange to me, but I guess it's 
just the result of having 64-bit addressing: a theoretically addressable 
area most of which will never actually be used?

Re: Wrong Vmalloc numbers in /proc/meminfo

[KAMEZAWA Hiroyuki]

On Mon, 28 Sep 2009 18:56:08 +0200
Frans Pop <elendil@planet.nl> wrote:

> On Monday 28 September 2009, KAMEZAWA Hiroyuki wrote:
> > > VmallocTotal:   34359738367 kB
> > > VmallocUsed:      340084 kB
> > > VmallocChunk:   34359387131 kB
> > >
> > > Is it me or are VmallocTotal and VmallocChunk off by a factor 10,000
> > > or so?
> >
> > I'm sorry I misunderstand your 10,000 implies.
> 
> What I meant is: is the Vmalloc area really 32 *terra*bytes in size?
> Seems rather big for a system with only 2GB RAM.
> 
VmallocTotal means "available address space size for VMALLOC"
It's fixed size as VMALLOC_END - VMALLOC_START.
VmallocChunk just means "free space in VMALLOC area".
Both of them are not related to size of RAM.

> I'd never noticed it before and it looks strange to me, but I guess it's 
> just the result of having 64-bit addressing: a theoretically addressable 
> area most of which will never actually be used?
> 
you're right. Most of space will never used.

Regards,
-Kame