From: Paolo Bonzini <pbonzini@redhat.com>
To: Dan Williams <dan.j.williams@intel.com>, Barret Rhoden <brho@google.com>
Cc: Dave Jiang <dave.jiang@intel.com>,
zwisler@kernel.org, Vishal L Verma <vishal.l.verma@intel.com>,
rkrcmar@redhat.com, Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
linux-nvdimm <linux-nvdimm@lists.01.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
"H. Peter Anvin" <hpa@zytor.com>, X86 ML <x86@kernel.org>,
KVM list <kvm@vger.kernel.org>,
"Zhang, Yu C" <yu.c.zhang@intel.com>,
"Zhang, Yi Z" <yi.z.zhang@intel.com>
Subject: Re: [RFC PATCH] kvm: Use huge pages for DAX-backed files
Date: Wed, 31 Oct 2018 09:52:04 +0100 [thread overview]
Message-ID: <e00c5f69-f4d7-859c-cbde-0392b0a5195c@redhat.com> (raw)
In-Reply-To: <CAPcyv4gJUjuSKwy7i2wuKR=Vz-AkDrxnGya5qkg7XTFxuXbtzw@mail.gmail.com>
On 29/10/2018 23:25, Dan Williams wrote:
> I'm wondering if we're adding an explicit is_zone_device_page() check
> in this path to determine the page mapping size if that can be a
> replacement for the kvm_is_reserved_pfn() check. In other words, the
> goal of fixing up PageReserved() was to preclude the need for DAX-page
> special casing in KVM, but if we already need add some special casing
> for page size determination, might as well bypass the
> kvm_is_reserved_pfn() dependency as well.
No, please don't. The kvm_is_reserved_pfn() check is for correctness,
the page-size check is for optimization. In theory you could have a
ZONE_DEVICE area that is smaller than 2MB and thus does not use huge pages.
Paolo
next prev parent reply other threads:[~2018-10-31 8:52 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-29 21:07 Barret Rhoden
2018-10-29 22:25 ` Dan Williams
2018-10-30 0:28 ` Barret Rhoden
2018-10-30 3:10 ` Dan Williams
2018-10-30 19:45 ` Barret Rhoden
2018-10-31 8:49 ` Paolo Bonzini
2018-11-02 20:32 ` Barret Rhoden
2018-11-06 10:19 ` Paolo Bonzini
2018-11-06 16:22 ` Barret Rhoden
2018-10-31 3:05 ` Yu Zhang
2018-10-31 8:52 ` Paolo Bonzini [this message]
2018-10-31 21:16 ` Dan Williams
2018-11-06 10:22 ` Paolo Bonzini
2018-11-06 21:05 ` Barret Rhoden
2018-11-06 21:16 ` Paolo Bonzini
2018-11-06 21:17 ` Barret Rhoden
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