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Re: [PATCH v2 7/9] memory: introduce RAM_NORESERVE and wire it up in qem
From: |
Peter Xu |
Subject: |
Re: [PATCH v2 7/9] memory: introduce RAM_NORESERVE and wire it up in qemu_ram_mmap() |
Date: |
Fri, 5 Mar 2021 10:37:13 -0500 |
On Fri, Mar 05, 2021 at 11:16:32AM +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 on Linux) is skipped: will bail out if not supported. When not
> set, the OS might reserve swap space (or huge pages on Linux), 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 the POSIX mmap implementation 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.
>
> Cc: Juan Quintela <quintela@redhat.com>
> Cc: Halil Pasic <pasic@linux.ibm.com>
> Cc: Cornelia Huck <cohuck@redhat.com>
> Cc: Christian Borntraeger <borntraeger@de.ibm.com>
> Cc: Thomas Huth <thuth@redhat.com>
> Cc: Stefan Weil <sw@weilnetz.de>
> Cc: kvm@vger.kernel.org
> Cc: qemu-s390x@nongnu.org
> Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
--
Peter Xu
- [PATCH v2 0/9] RAM_NORESERVE, MAP_NORESERVE and hostmem "reserve" property, David Hildenbrand, 2021/03/05
- [PATCH v2 1/9] softmmu/physmem: Drop "shared" parameter from ram_block_add(), David Hildenbrand, 2021/03/05
- [PATCH v2 2/9] util/mmap-alloc: Factor out calculation of the pagesize for the guard page, David Hildenbrand, 2021/03/05
- [PATCH v2 3/9] util/mmap-alloc: Factor out reserving of a memory region to mmap_reserve(), David Hildenbrand, 2021/03/05
- [PATCH v2 4/9] util/mmap-alloc: Factor out activating of memory to mmap_activate(), David Hildenbrand, 2021/03/05
- [PATCH v2 5/9] softmmu/memory: Pass ram_flags into qemu_ram_alloc_from_fd(), David Hildenbrand, 2021/03/05
- [PATCH v2 6/9] softmmu/memory: Pass ram_flags into memory_region_init_ram_shared_nomigrate(), David Hildenbrand, 2021/03/05
- [PATCH v2 7/9] memory: introduce RAM_NORESERVE and wire it up in qemu_ram_mmap(), David Hildenbrand, 2021/03/05
- Re: [PATCH v2 7/9] memory: introduce RAM_NORESERVE and wire it up in qemu_ram_mmap(),
Peter Xu <=
- [PATCH v2 8/9] util/mmap-alloc: Support RAM_NORESERVE via MAP_NORESERVE, David Hildenbrand, 2021/03/05
- Re: [PATCH v2 8/9] util/mmap-alloc: Support RAM_NORESERVE via MAP_NORESERVE, Peter Xu, 2021/03/05
- Re: [PATCH v2 8/9] util/mmap-alloc: Support RAM_NORESERVE via MAP_NORESERVE, David Hildenbrand, 2021/03/05
- Re: [PATCH v2 8/9] util/mmap-alloc: Support RAM_NORESERVE via MAP_NORESERVE, Peter Xu, 2021/03/05
- Re: [PATCH v2 8/9] util/mmap-alloc: Support RAM_NORESERVE via MAP_NORESERVE, David Hildenbrand, 2021/03/05
- Re: [PATCH v2 8/9] util/mmap-alloc: Support RAM_NORESERVE via MAP_NORESERVE, David Hildenbrand, 2021/03/07
- Re: [PATCH v2 8/9] util/mmap-alloc: Support RAM_NORESERVE via MAP_NORESERVE, Marcel Apfelbaum, 2021/03/07
- Re: [PATCH v2 8/9] util/mmap-alloc: Support RAM_NORESERVE via MAP_NORESERVE, David Hildenbrand, 2021/03/08
- Re: [PATCH v2 8/9] util/mmap-alloc: Support RAM_NORESERVE via MAP_NORESERVE, Marcel Apfelbaum, 2021/03/08
[PATCH v2 9/9] hostmem: Wire up RAM_NORESERVE via "reserve" property, David Hildenbrand, 2021/03/05