diff options
Diffstat (limited to 'Documentation/sysctl')
| -rw-r--r-- | Documentation/sysctl/vm.txt | 19 |
1 files changed, 10 insertions, 9 deletions
diff --git a/Documentation/sysctl/vm.txt b/Documentation/sysctl/vm.txt index cb0368459da3..34a5fece3121 100644 --- a/Documentation/sysctl/vm.txt +++ b/Documentation/sysctl/vm.txt @@ -581,15 +581,16 @@ Specify "[Nn]ode" for node order "Zone Order" orders the zonelists by zone type, then by node within each zone. Specify "[Zz]one" for zone order. -Specify "[Dd]efault" to request automatic configuration. Autoconfiguration -will select "node" order in following case. -(1) if the DMA zone does not exist or -(2) if the DMA zone comprises greater than 50% of the available memory or -(3) if any node's DMA zone comprises greater than 70% of its local memory and - the amount of local memory is big enough. - -Otherwise, "zone" order will be selected. Default order is recommended unless -this is causing problems for your system/application. +Specify "[Dd]efault" to request automatic configuration. + +On 32-bit, the Normal zone needs to be preserved for allocations accessible +by the kernel, so "zone" order will be selected. + +On 64-bit, devices that require DMA32/DMA are relatively rare, so "node" +order will be selected. + +Default order is recommended unless this is causing problems for your +system/application. ============================================================== |