2001-02-05 06:37:56

by L A Walsh

[permalink] [raw]
Subject: 2.4.x Shared memory question


Another oddity -- I notice things taking alot more memory
in 2.4. This coincides with 'top' consistently showing I have 0 shared
memory. These two observations would have me wondering if I
have somehow misconfigured my system to disallow sharing. Note
that /proc/meminfo also shows 0 shared memory:

total: used: free: shared: buffers: cached:
Mem: 525897728 465264640 60633088 0 82145280 287862784
Swap: 270909440 0 270909440
MemTotal: 513572 kB
MemFree: 59212 kB
MemShared: 0 kB
Buffers: 80220 kB
Cached: 281116 kB
Active: 22340 kB
Inact_dirty: 338996 kB
Inact_clean: 0 kB
Inact_target: 0 kB
HighTotal: 0 kB
HighFree: 0 kB
LowTotal: 513572 kB
LowFree: 59212 kB
SwapTotal: 264560 kB
SwapFree: 264560 kB

Not that it seems unrelated, but I do have filesystem type shm
mounted on /dev/shm as suggested for POSIX shared memory.


--
Linda A Walsh | Trust Technology, Core Linux, SGI
[email protected] | Voice: (650) 933-5338



--
Linda A Walsh | Trust Technology, Core Linux, SGI
[email protected] | Voice: (650) 933-5338


2001-02-05 15:52:09

by Shawn Starr

[permalink] [raw]
Subject: Re: 2.4.x Shared memory question

Its supposed to, its too costly to calculate shared memory with the new VM
I'm told.

Shawn.

LA Walsh wrote:

> Another oddity -- I notice things taking alot more memory
> in 2.4. This coincides with 'top' consistently showing I have 0 shared
> memory. These two observations would have me wondering if I
> have somehow misconfigured my system to disallow sharing. Note
> that /proc/meminfo also shows 0 shared memory:
>
> total: used: free: shared: buffers: cached:
> Mem: 525897728 465264640 60633088 0 82145280 287862784
> Swap: 270909440 0 270909440
> MemTotal: 513572 kB
> MemFree: 59212 kB
> MemShared: 0 kB
> Buffers: 80220 kB
> Cached: 281116 kB
> Active: 22340 kB
> Inact_dirty: 338996 kB
> Inact_clean: 0 kB
> Inact_target: 0 kB
> HighTotal: 0 kB
> HighFree: 0 kB
> LowTotal: 513572 kB
> LowFree: 59212 kB
> SwapTotal: 264560 kB
> SwapFree: 264560 kB
>
> Not that it seems unrelated, but I do have filesystem type shm
> mounted on /dev/shm as suggested for POSIX shared memory.
>
> --
> Linda A Walsh | Trust Technology, Core Linux, SGI
> [email protected] | Voice: (650) 933-5338
>
> --
> Linda A Walsh | Trust Technology, Core Linux, SGI
> [email protected] | Voice: (650) 933-5338
> -
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to [email protected]
> Please read the FAQ at http://www.tux.org/lkml/

2001-02-06 00:13:11

by Rogerio Brito

[permalink] [raw]
Subject: What is the difference between buffers and cached? (was: Re: 2.4.x Shared memory question)

On Feb 04 2001, LA Walsh wrote:
> Another oddity -- I notice things taking alot more memory
> in 2.4. This coincides with 'top' consistently showing I have 0 shared
> memory.

AFAIK, the 2.4.0 series does share memory, but it's just the
counters that are not updated, for they are costly.

> total: used: free: shared: buffers: cached:
> Mem: 525897728 465264640 60633088 0 82145280 287862784
> Swap: 270909440 0 270909440

This is the perfect time to ask one thing that I don't know,
but that I've tried to find without success: what is the
difference between "buffers" and "cached"? I'd make the wild
guess that "buffers" would mean any types of buffers that the
kernel maintains, while "cached" would have something to do
with cached disk blocks...

Are these guesses correct or completely, way off?


Thanks for any hints, Roger...

--
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Rogerio Brito - [email protected] - http://www.ime.usp.br/~rbrito/
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