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Re: [PATCH v4 10/14] memory: Introduce RAM_NORESERVE and wire it up in q
From: |
Peter Xu |
Subject: |
Re: [PATCH v4 10/14] memory: Introduce RAM_NORESERVE and wire it up in qemu_ram_mmap() |
Date: |
Tue, 23 Mar 2021 16:51:56 -0400 |
On Fri, Mar 19, 2021 at 11:12:26AM +0100, David Hildenbrand wrote:
> Let's introduce RAM_NORESERVE, allowing mmap'ing with MAP_NORESERVE. The
> new flag has the following semantics:
>
> "
> RAM is mmap-ed with MAP_NORESERVE. When set, reserving swap space (or huge
> pages if applicable) is skipped: will bail out if not supported. When not
> set, the OS might do the reservation, depending on OS support.
> "
>
> Allow passing it into:
> - memory_region_init_ram_nomigrate()
> - memory_region_init_resizeable_ram()
> - memory_region_init_ram_from_file()
>
> ... and teach qemu_ram_mmap() and qemu_anon_ram_alloc() about the flag.
> Bail out if the flag is not supported, which is the case right now for
> both, POSIX and win32. We will add Linux support next and allow specifying
> RAM_NORESERVE via memory backends.
>
> The target use case is virtio-mem, which dynamically exposes memory
> inside a large, sparse memory area to the VM.
>
> Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
--
Peter Xu
- Re: [PATCH v4 03/14] softmmu/physmem: Fix qemu_ram_remap() to handle shared anonymous memory, (continued)
- [PATCH v4 04/14] util/mmap-alloc: Factor out calculation of the pagesize for the guard page, David Hildenbrand, 2021/03/19
- [PATCH v4 05/14] util/mmap-alloc: Factor out reserving of a memory region to mmap_reserve(), David Hildenbrand, 2021/03/19
- [PATCH v4 06/14] util/mmap-alloc: Factor out activating of memory to mmap_activate(), David Hildenbrand, 2021/03/19
- [PATCH v4 07/14] softmmu/memory: Pass ram_flags to qemu_ram_alloc_from_fd(), David Hildenbrand, 2021/03/19
- [PATCH v4 08/14] softmmu/memory: Pass ram_flags to memory_region_init_ram_shared_nomigrate(), David Hildenbrand, 2021/03/19
- [PATCH v4 09/14] util/mmap-alloc: Pass flags instead of separate bools to qemu_ram_mmap(), David Hildenbrand, 2021/03/19
- [PATCH v4 10/14] memory: Introduce RAM_NORESERVE and wire it up in qemu_ram_mmap(), David Hildenbrand, 2021/03/19
- Re: [PATCH v4 10/14] memory: Introduce RAM_NORESERVE and wire it up in qemu_ram_mmap(),
Peter Xu <=
- [PATCH v4 11/14] util/mmap-alloc: Support RAM_NORESERVE via MAP_NORESERVE under Linux, David Hildenbrand, 2021/03/19
- [PATCH v4 12/14] hostmem: Wire up RAM_NORESERVE via "reserve" property, David Hildenbrand, 2021/03/19
- [PATCH v4 13/14] qmp: Include "reserve" property of memory backends, David Hildenbrand, 2021/03/19
[PATCH v4 14/14] hmp: Print "reserve" property of memory backends with "info memdev", David Hildenbrand, 2021/03/19