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Date: Thu, 18 Dec 2014 17:51:19 +0000 From: "Yu, Fenghua" <fenghua.yu@...el.com> To: "H. Peter Anvin" <hpa@...or.com>, Thomas Gleixner <tglx@...utronix.de>, "H. Peter Anvin" <hpa@...ux.intel.com>, Ingo Molnar <mingo@...e.hu>, "Williamson, Glenn P" <glenn.p.williamson@...el.com> CC: linux-kernel <linux-kernel@...r.kernel.org>, x86 <x86@...nel.org> Subject: RE: [PATCH v2] X86-32: Allocate 256 bytes for pgd in PAE paging > 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@...el.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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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