On 2012?01?31? 17:29, Catalin Marinas wrote:

Hi,

On 30 January 2012 07:57,[off-list ref]  wrote:

quoted

This patch aims to support huge page for ARM. For now, 2MB(two 1MB page)/16MB
huge page are supported, Versatile Express Cortex-A9x4 tile is used as test
board. Verifications are running with libhugetlbfs and ltp.

I haven't reviewed your patches yet but just a few thoughts. Do you
have a clear case where 16MB super-sections is needed? Do you have
memory beyond 4G that can only be accessed with super-sections? This
is an optional feature and not all processors have it.

The initial support only focus on ARMv7 based processor like cortex A9, 
basically that's
what I got in my hand, one Versatile Express Cortex-A9x4 tile board.

It also doesn't
help much with the TLB hit rate since the micro-TLB most likely only
support 1MB sections.

I am afraid I can't agree with you on this.
Truly there is no specific statement about whether micro-TLB support 
16MB super-sections,
but main-TLB actually helps the hit rate, and main-TLB support all page 
size mapping.

BTW, I have a (simpler) implementation of hugetlbfs with 2MB sections
but for LPAE only:

http://git.kernel.org/?p=linux/kernel/git/cmarinas/linux-arm-arch.git;a=shortlog;h=refs/heads/hugetlb

Thanks for your information, I will study your code carefully :)



-- 
I am a slow learner
but I will keep trying to fight for my dreams!

--bill