Subject: Re: 4MB pages?
To: None <firstname.lastname@example.org>
From: Matt Thomas <email@example.com>
Date: 09/06/2000 08:16:42
At 07:11 AM 9/6/2000 -0700, Jason R Thorpe wrote:
>On Wed, Sep 06, 2000 at 02:10:05PM +0200, Hubert Feyrer wrote:
> > Seeing this jump from few kb pages to few MB pages looks ... interresting.
> > What's the background on this?
> > Is it intended to make switch pagesize on i386 unconditionally?
>No, the i386 port will use a combination of 4K and 4MB pages. The idea is
>to use a 4MB page for the kernel text+data+bss to reduce TLB usage for the
>kernel, thus improving overall performance.
>See the Intel IA32 system programmers reference manual.
For memory intensive (mmap large files, etc.) programs, I was wondering whether
it would be useful to have another uvm free page area which contains free 4MB
blocks. As memory gets freed, as a complete 4MB block is freed it would be
moved to the free 4MB list.
4MB page table entries would be real useful for mapping framebuffers as
that requires a[nother] change to the driver mmap interface.
Note that these idea are applicable to other architectures that support
such as alpha.
Matt Thomas Internet: firstname.lastname@example.org
3am Software Foundry WWW URL: http://www.3am-software.com/bio/matt/
Cupertino, CA Disclaimer: I avow all knowledge of this message