Is this is a question that popped up to your mind arbitrarily or do you have a specific system at hand which triggered you to ponder over the design of the kernel ? I felt the answer to this question is not straight forward but is multi faceted and to be discussed in a specific context.
On Sat, May 11, 2013 at 9:02 AM, Paul Davies C <pauldavi...@gmail.com>wrote: > > In a system with 3:1 split, the ZONE_NORMAL with a size of 896MB is > permanently mapped to the kernel address space.This leaves a 128MB free > space in the Kernel address space and according to my understanding, the > ZONE_HIGHMEM pages are mapped temporarily to this 128MB part. If the system > actually had a 4GB physical memory you will be mapping(not smultaneously) > the HIHGMEM part- which is roughly 3.2GB - to this 128MB part. If that was > the case Kernel would have to frequently access HIHGMEM which implicates a > frequent change in temporaty mapping and that in my view is a penalty. So > what was the reason why ZONE_NORMAL fixed at 896MB and not something really > lower? > > -- > *Regards,* > *Paul Davies C* > vivafoss.blogspot.com > > -- Regards, Prabhunath G Linux Trainer Bangalore
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