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From: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
To: Christophe Leroy <christophe.leroy@c-s.fr>,
        Nicholas Piggin <npiggin@gmail.com>
Cc: linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org
Subject: Re: [RFC REBASED 5/5] powerpc/mm/slice: use the dynamic high slice size to limit bitmap operations
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Christophe Leroy <christophe.leroy@c-s.fr> writes:

> The number of high slices a process might use now depends on its
> address space size, and what allocation address it has requested.
>
> This patch uses that limit throughout call chains where possible,
> rather than use the fixed SLICE_NUM_HIGH for bitmap operations.
> This saves some cost for processes that don't use very large address
> spaces.

I haven't really looked at the final code. One of the issue we had was
with the below scenario.

mmap(addr, len) where addr < 128TB and addr+len > 128TB  We want to make
sure we build the mask such that we don't find the addr available.

-aneesh