Re: [PATCH 1/1] arm64/sparsemem: reduce SECTION_SIZE_BITS

[Catalin Marinas]

On Thu, Jan 21, 2021 at 10:08:17AM +0000, Christoph Lameter wrote:
> On Wed, 20 Jan 2021, Sudarshan Rajagopalan wrote:
> 
> > But there are other problems in reducing SECTION_SIZE_BIT. Reducing it by too
> > much would over populate /sys/devices/system/memory/ and also consume too many
> > page->flags bits in the !vmemmap case. Also section size needs to be multiple
> > of 128MB to have PMD based vmemmap mapping with CONFIG_ARM64_4K_PAGES.
> 
> There is also the issue of requiring more space in the TLB cache with
> smaller page sizes. Or does ARM resolve these into smaller TLB entries
> anyways (going on my x86 kwon how here)? Anyways if there are only a few
> TLB entries then the effect could
> be significant.

There is indeed more TLB pressure with smaller page sizes but this patch
doesn't change this.

-- 
Catalin