forked from luck/tmp_suning_uos_patched
docs/vm: balance: convert to ReST format
Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com> Signed-off-by: Jonathan Corbet <corbet@lwn.net>
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@ -1,3 +1,9 @@
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.. _balance:
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================
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Memory Balancing
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================
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Started Jan 2000 by Kanoj Sarcar <kanoj@sgi.com>
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Memory balancing is needed for !__GFP_ATOMIC and !__GFP_KSWAPD_RECLAIM as
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@ -62,11 +68,11 @@ for non-sleepable allocations. Second, the HIGHMEM zone is also balanced,
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so as to give a fighting chance for replace_with_highmem() to get a
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HIGHMEM page, as well as to ensure that HIGHMEM allocations do not
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fall back into regular zone. This also makes sure that HIGHMEM pages
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are not leaked (for example, in situations where a HIGHMEM page is in
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are not leaked (for example, in situations where a HIGHMEM page is in
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the swapcache but is not being used by anyone)
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kswapd also needs to know about the zones it should balance. kswapd is
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primarily needed in a situation where balancing can not be done,
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primarily needed in a situation where balancing can not be done,
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probably because all allocation requests are coming from intr context
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and all process contexts are sleeping. For 2.3, kswapd does not really
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need to balance the highmem zone, since intr context does not request
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@ -89,7 +95,8 @@ pages is below watermark[WMARK_LOW]; in which case zone_wake_kswapd is also set.
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(Good) Ideas that I have heard:
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1. Dynamic experience should influence balancing: number of failed requests
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for a zone can be tracked and fed into the balancing scheme (jalvo@mbay.net)
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for a zone can be tracked and fed into the balancing scheme (jalvo@mbay.net)
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2. Implement a replace_with_highmem()-like replace_with_regular() to preserve
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dma pages. (lkd@tantalophile.demon.co.uk)
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dma pages. (lkd@tantalophile.demon.co.uk)
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