Re: Memory usage analysis

[Anand Raj Manickam <anandrm@xxxxxxxxx>]

On Wed, Mar 31, 2010 at 9:49 PM, Mulyadi Santosa <mulyadi.santosa@xxxxxxxxx> wrote:

Hi...

On Wed, Mar 31, 2010 at 17:38, Anand Raj Manickam <anandrm@xxxxxxxxx> wrote:
>
> Using these tools i m able to account roughly around
>
> 100 MB of user space data
> 20 MB of kernel space (slab allocs)
> The total memory is around 512MB  out of which i m able to account only for
> 120MB of memory .

What you might forgot is the fact that some user space programs (if
not all, in some cases) share some of its memory with others in the
form of shared library, system V shared memory etc. Thus, user space
memory consumption could be smaller than you think. Top, AFAIK, does
not count on this fact.

I suggest you look directly at /proc/<pid>/status, specifically its
VmRSS. AFAIK, this field better describe the memory consumption of a
process. If you need better precision, once I recall there was a patch
from Matt Mckall that does more precise memory accounting.

About kernel space memory assumption, I agree with Srdjan that you
seems missed out the buffer + cache. Further, if you take a look on
/proc/meminfo, there are fields like page tables, vmalloc, kernel
stack etc that form the kernel mode of memory consumption.

Hope it helps

This is a snapshot of meminfo and free

debian:~# cat /proc/meminfo
MemTotal:       508612 kB
MemFree:         12428 kB
Buffers:         94252 kB
Cached:         304792 kB
SwapCached:          0 kB
Active:         267896 kB
Inactive:       188088 kB
HighTotal:           0 kB
HighFree:            0 kB
LowTotal:       508612 kB
LowFree:         12428 kB
SwapTotal:     1485972 kB
SwapFree:      1485908 kB
Dirty:             132 kB
Writeback:           0 kB
AnonPages:       56944 kB
Mapped:          14656 kB
Slab:            34724 kB
SReclaimable:    28268 kB
SUnreclaim:       6456 kB
PageTables:        836 kB
NFS_Unstable:        0 kB
Bounce:              0 kB
WritebackTmp:        0 kB
CommitLimit:   1740276 kB
Committed_AS:   662780 kB
VmallocTotal:   516088 kB
VmallocUsed:      3696 kB
VmallocChunk:   511860 kB
debian:~#
debian:~#
debian:~# free
                      total       used       free     shared    buffers     cached
Mem:        508612     496184      12428          0      94260     304792
-/+ buffers/cache:      97132     411480
Swap:      1485972         64    1485908
debian:~#

I guess free derives all the info from meminfo .

Still can someone shed some light on buffers and cached ?













 

--
regards,

Mulyadi Santosa
Freelance Linux trainer and consultant

blog: the-hydra.blogspot.com
training: mulyaditraining.blogspot.com