Re: buffer/memory strangeness in 2.4.16

Andrew Morton (akpm@zip.com.au)
Fri, 30 Nov 2001 01:29:58 -0800


space-00002@vortex.physik.uni-konstanz.de wrote:
>
> Hi,
>
> I am experiencing a bit of strange system behaviour in a vanilla 2.4.16
> kernel (2.95.3, very stable machine etc.)
>
> I noticed, that after running for a while (day) I had significantly less
> memory available for my simulation program than right after booting. Looking
> at the problem using 'xosview' (or 'free'), I noticed that there was a large
> number of MBs filled with 'buffers' that did not get wiped when other
> programs need the memory. The system seems to rather kill an 'offender' than
> clean out buffers.
>
>

Seconded. After an updatedb run, my 768 megabyte 2.5.1-pre4 machine
shows:

total used free shared buffers cached
Mem: 770668 384460 386208 0 138548 17744
-/+ buffers/cache: 228168 542500

and, after malloc/memset of 700 megs:

total used free shared buffers cached
Mem: 770668 73340 697328 0 41160 5960
-/+ buffers/cache: 26220 744448
Swap: 499928 18628 481300

I repeated the malloc/memset a few times, wrote a gigabyte file
and was unable to make the 40 megabytes of buffermem go away.

MemTotal: 770668 kB
MemFree: 698008 kB
MemShared: 0 kB
Buffers: 42092 kB
Cached: 6088 kB
SwapCached: 9808 kB
Active: 48064 kB
Inactive: 10112 kB
HighTotal: 0 kB
HighFree: 0 kB
LowTotal: 770668 kB
LowFree: 698008 kB
SwapTotal: 499928 kB
SwapFree: 484512 kB

After running an extremely memory-intensive test program for
two minutes, buffermem fell to 38 megabytes.

Seems broken to me.

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