Messages in this thread | | | From | "Yu, Fenghua" <> | Subject | RE: [PATCH v2] X86-32: Allocate 256 bytes for pgd in PAE paging | Date | Thu, 18 Dec 2014 17:51:19 +0000 |
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> Sent: Thursday, December 18, 2014 9:26 AM > To: Yu, Fenghua; Thomas Gleixner; H. Peter Anvin; Ingo Molnar; Williamson, > Glenn P > Cc: linux-kernel; x86 > Subject: Re: [PATCH v2] X86-32: Allocate 256 bytes for pgd in PAE paging > > On 12/17/2014 01:47 PM, Fenghua Yu wrote: > > From: Fenghua Yu <fenghua.yu@intel.com> > > > > X86 32-bit machine and kernel use PAE paging, which currently wastes > > about 4K of memory per process on Linux where we have to reserve an > > entire page to support a single 256-byte PGD structure. It would be a > > very good thing if we could eliminate that wastage. > > > > 4*8 = 32 bytes, where did 256 bytes come from?
You are right. It should be 32 bytes. I will change the wording in future patch. The real calculation in code is right though.
Thanks.
-Fenghua
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