Documentation/vm/balance really outdated

Documentation/vm/balance really outdated

[Marcelo Tosatti]

Hi guys,

The file Documentation/vm/balance was written by Kanoj in 2000, and is completly outdated 
to what we have now.

Last paragraph:

pages_min/pages_low/pages_high/low_on_memory/zone_wake_kswapd: These are
per-zone fields, used to determine when a zone needs to be balanced. When
the number of pages falls below pages_min, the hysteric field low_on_memory
gets set. This stays set till the number of free pages becomes pages_high.
When low_on_memory is set, page allocation requests will try to free some
pages in the zone (providing GFP_WAIT is set in the request). Orthogonal
to this, is the decision to poke kswapd to free some zone pages. That
decision is not hysteresis based, and is done when the number of free
pages is below pages_low; in which case zone_wake_kswapd is also set.

Should we just remove it? 

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Re: Documentation/vm/balance really outdated

[Kanoj Sarcar]

Hi,

--- Marcelo Tosatti <marcelo.tosatti@cyclades.com>
wrote:

> Hi guys,
> 
> The file Documentation/vm/balance was written by
> Kanoj in 2000, and is completly outdated 
> to what we have now.
> 
> Last paragraph:
> 
>
pages_min/pages_low/pages_high/low_on_memory/zone_wake_kswapd:
> These are
> per-zone fields, used to determine when a zone needs
> to be balanced. When
> the number of pages falls below pages_min, the
> hysteric field low_on_memory
> gets set. This stays set till the number of free
> pages becomes pages_high.
> When low_on_memory is set, page allocation requests
> will try to free some
> pages in the zone (providing GFP_WAIT is set in the
> request). Orthogonal
> to this, is the decision to poke kswapd to free some
> zone pages. That
> decision is not hysteresis based, and is done when
> the number of free
> pages is below pages_low; in which case
> zone_wake_kswapd is also set.
> 
> Should we just remove it? 
> 

Thats the easy solution; a better one would be if 
some (one | people) volunteer(s) to update that file.

If you do remove it, also consider the files "numa"
and "locking" for removal/updates, I know they are 
also quite out of date.

Thanks.

Kanoj



		
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Re: Documentation/vm/balance really outdated

[William Lee Irwin III]

On Wed, Aug 25, 2004 at 03:45:20PM -0300, Marcelo Tosatti wrote:
> The file Documentation/vm/balance was written by Kanoj in 2000, and
> is completly outdated to what we have now.
> Last paragraph:
> pages_min/pages_low/pages_high/low_on_memory/zone_wake_kswapd: These are
> per-zone fields, used to determine when a zone needs to be balanced. When
> the number of pages falls below pages_min, the hysteric field low_on_memory
> gets set. This stays set till the number of free pages becomes pages_high.
> When low_on_memory is set, page allocation requests will try to free some
> pages in the zone (providing GFP_WAIT is set in the request). Orthogonal
> to this, is the decision to poke kswapd to free some zone pages. That
> decision is not hysteresis based, and is done when the number of free
> pages is below pages_low; in which case zone_wake_kswapd is also set.
> Should we just remove it? 

pages_min, pages_low, and pages_high are still in use, but with more
precisely-defined semantics. low_on_memory is gone, and min_free_kb,
overcommit_memory, and swappiness have arrived for different purposes.
I find the value of this documentation rather unclear particularly given
that it's not been examined in so long. Maybe kerneldoc is the way.


-- wli
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