diff options
| -rw-r--r-- | Documentation/vm/balance | 15 |
1 files changed, 11 insertions, 4 deletions
diff --git a/Documentation/vm/balance b/Documentation/vm/balance index 964595481af6..6a1fadf3e173 100644 --- a/Documentation/vm/balance +++ b/Documentation/vm/balance @@ -1,3 +1,9 @@ +.. _balance: + +================ +Memory Balancing +================ + Started Jan 2000 by Kanoj Sarcar <kanoj@sgi.com> Memory balancing is needed for !__GFP_ATOMIC and !__GFP_KSWAPD_RECLAIM as @@ -62,11 +68,11 @@ for non-sleepable allocations. Second, the HIGHMEM zone is also balanced, so as to give a fighting chance for replace_with_highmem() to get a HIGHMEM page, as well as to ensure that HIGHMEM allocations do not fall back into regular zone. This also makes sure that HIGHMEM pages -are not leaked (for example, in situations where a HIGHMEM page is in +are not leaked (for example, in situations where a HIGHMEM page is in the swapcache but is not being used by anyone) kswapd also needs to know about the zones it should balance. kswapd is -primarily needed in a situation where balancing can not be done, +primarily needed in a situation where balancing can not be done, probably because all allocation requests are coming from intr context and all process contexts are sleeping. For 2.3, kswapd does not really need to balance the highmem zone, since intr context does not request @@ -89,7 +95,8 @@ pages is below watermark[WMARK_LOW]; in which case zone_wake_kswapd is also set. (Good) Ideas that I have heard: + 1. Dynamic experience should influence balancing: number of failed requests -for a zone can be tracked and fed into the balancing scheme (jalvo@mbay.net) + for a zone can be tracked and fed into the balancing scheme (jalvo@mbay.net) 2. Implement a replace_with_highmem()-like replace_with_regular() to preserve -dma pages. (lkd@tantalophile.demon.co.uk) + dma pages. (lkd@tantalophile.demon.co.uk) |