[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-devel] [PATCH] mmap-alloc: use same backend for all mappings
From: |
Aneesh Kumar K.V |
Subject: |
Re: [Qemu-devel] [PATCH] mmap-alloc: use same backend for all mappings |
Date: |
Tue, 01 Dec 2015 16:23:11 +0530 |
User-agent: |
Notmuch/0.20.2 (http://notmuchmail.org) Emacs/24.5.1 (x86_64-pc-linux-gnu) |
"Michael S. Tsirkin" <address@hidden> writes:
> On Mon, Nov 30, 2015 at 02:46:31PM +0100, Greg Kurz wrote:
>> On Mon, 30 Nov 2015 15:06:33 +0200
>> "Michael S. Tsirkin" <address@hidden> wrote:
>>
....
>>
>> On ppc64, the address space is divided in 256MB-sized segments where all
>> pages
>> have the same size. This is a hw limitation IIUC. I don't know if it can be
>> fixed and I'll let Ben comment on it.
>
> But it's anonymous memory with PROT_NONE. There should be no pages there:
> just a chunk of virtual memory reserved.
>
ppc64 use page size (called as base page size) to find the hash slot in
which we find the virtual address to real address translation. All the
pages in a segment should have same base page size. Hugetlb pages have a
base page size of 16M whereas a regular linux page have 64K. mmap will
fail to map a hugetlb mapping in a segment that already have regular
pages mapped.
-aneesh
- Re: [Qemu-devel] [PATCH] mmap-alloc: use same backend for all mappings,
Aneesh Kumar K.V <=