From: Eduardo Habkost <ehabkost@redhat.com>
To: David Hildenbrand <david@redhat.com>
Cc: "Marcel Apfelbaum" <mapfelba@redhat.com>,
"Michael S. Tsirkin" <mst@redhat.com>,
"Murilo Opsfelder Araujo" <muriloo@linux.ibm.com>,
"Richard Henderson" <richard.henderson@linaro.org>,
"Dr. David Alan Gilbert" <dgilbert@redhat.com>,
"Peter Xu" <peterx@redhat.com>,
qemu-devel@nongnu.org, "Greg Kurz" <groug@kaod.org>,
"Stefan Hajnoczi" <stefanha@redhat.com>,
"Igor Mammedov" <imammedo@redhat.com>,
"Paolo Bonzini" <pbonzini@redhat.com>,
"Philippe Mathieu-Daudé" <philmd@redhat.com>
Subject: Re: [PATCH v6 00/15] RAM_NORESERVE, MAP_NORESERVE and hostmem "reserve" property
Date: Wed, 21 Apr 2021 17:06:11 -0400 [thread overview]
Message-ID: <20210421210611.wradfrdrbw6ebcdn@habkost.net> (raw)
In-Reply-To: <20210421122624.12292-1-david@redhat.com>
On Wed, Apr 21, 2021 at 02:26:09PM +0200, David Hildenbrand wrote:
> Based-on: 20210406080126.24010-1-david@redhat.com
>
> Some cleanups previously sent in other context (resizeable allocations),
> followed by RAM_NORESERVE, implementing it under Linux using MAP_NORESERVE,
> and letting users configure it for memory backens using the "reserve"
> property (default: true).
>
> MAP_NORESERVE under Linux has in the context of QEMU an effect on
> 1) Private/shared anonymous memory
> -> memory-backend-ram,id=mem0,size=10G
> 2) Private fd-based mappings
> -> memory-backend-file,id=mem0,size=10G,mem-path=/dev/shm/0
> -> memory-backend-memfd,id=mem0,size=10G
> 3) Private/shared hugetlb mappings
> -> memory-backend-memfd,id=mem0,size=10G,hugetlb=on,hugetlbsize=2M
>
> With MAP_NORESERVE/"reserve=off", we won't be reserving swap space (1/2) or
> huge pages (3) for the whole memory region.
>
> The target use case is virtio-mem, which dynamically exposes memory
> inside a large, sparse memory area to the VM. MAP_NORESERVE tells the OS
> "this mapping might be very sparse". This essentially allows
> avoiding having to set "/proc/sys/vm/overcommit_memory == 1") when using
> virtio-mem and also supporting hugetlbfs in the future.
For the memory backend and machine core code:
Acked-by: Eduardo Habkost <ehabkost@redhat.com>
--
Eduardo
next prev parent reply other threads:[~2021-04-21 21:07 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-21 12:26 [PATCH v6 00/15] RAM_NORESERVE, MAP_NORESERVE and hostmem "reserve" property David Hildenbrand
2021-04-21 12:26 ` [PATCH v6 01/15] util/mmap-alloc: Factor out calculation of the pagesize for the guard page David Hildenbrand
2021-04-21 12:26 ` [PATCH v6 02/15] util/mmap-alloc: Factor out reserving of a memory region to mmap_reserve() David Hildenbrand
2021-04-21 12:26 ` [PATCH v6 03/15] util/mmap-alloc: Factor out activating of memory to mmap_activate() David Hildenbrand
2021-04-21 12:26 ` [PATCH v6 04/15] softmmu/memory: Pass ram_flags to qemu_ram_alloc_from_fd() David Hildenbrand
2021-04-21 12:26 ` [PATCH v6 05/15] softmmu/memory: Pass ram_flags to memory_region_init_ram_shared_nomigrate() David Hildenbrand
2021-04-21 12:33 ` Philippe Mathieu-Daudé
2021-04-21 12:26 ` [PATCH v6 06/15] softmmu/memory: Pass ram_flags to qemu_ram_alloc() and qemu_ram_alloc_internal() David Hildenbrand
2021-04-21 12:34 ` Philippe Mathieu-Daudé
2021-04-21 12:26 ` [PATCH v6 07/15] util/mmap-alloc: Pass flags instead of separate bools to qemu_ram_mmap() David Hildenbrand
2021-04-21 12:37 ` Philippe Mathieu-Daudé
2021-04-21 12:26 ` [PATCH v6 08/15] memory: Introduce RAM_NORESERVE and wire it up in qemu_ram_mmap() David Hildenbrand
2021-04-21 12:26 ` [PATCH v6 09/15] util/mmap-alloc: Support RAM_NORESERVE via MAP_NORESERVE under Linux David Hildenbrand
2021-04-21 12:26 ` [PATCH v6 10/15] hostmem: Wire up RAM_NORESERVE via "reserve" property David Hildenbrand
2021-04-23 11:14 ` Markus Armbruster
2021-04-23 11:16 ` David Hildenbrand
2021-04-23 12:11 ` Markus Armbruster
2021-04-23 11:18 ` David Hildenbrand
2021-04-23 12:10 ` Markus Armbruster
2021-04-23 14:21 ` David Hildenbrand
2021-04-23 14:53 ` Markus Armbruster
2021-04-21 12:26 ` [PATCH v6 11/15] qmp: Clarify memory backend properties returned via query-memdev David Hildenbrand
2021-04-21 21:00 ` Eduardo Habkost
2021-04-23 10:55 ` Markus Armbruster
2021-04-21 12:26 ` [PATCH v6 12/15] qmp: Include "share" property of memory backends David Hildenbrand
2021-04-21 21:01 ` Eduardo Habkost
2021-04-23 11:15 ` Markus Armbruster
2021-04-21 12:26 ` [PATCH v6 13/15] hmp: Print "share" property of memory backends with "info memdev" David Hildenbrand
2021-04-21 21:04 ` Eduardo Habkost
2021-04-23 11:15 ` Markus Armbruster
2021-04-21 12:26 ` [PATCH v6 14/15] qmp: Include "reserve" property of memory backends David Hildenbrand
2021-04-21 21:05 ` Eduardo Habkost
2021-04-23 11:00 ` Markus Armbruster
2021-04-23 11:03 ` David Hildenbrand
2021-04-23 11:21 ` Markus Armbruster
2021-04-23 11:33 ` David Hildenbrand
2021-04-23 12:13 ` Markus Armbruster
2021-04-23 12:29 ` David Hildenbrand
2021-04-23 14:13 ` David Hildenbrand
2021-04-23 14:55 ` Markus Armbruster
2021-04-23 15:04 ` David Hildenbrand
2021-04-21 12:26 ` [PATCH v6 15/15] hmp: Print "reserve" property of memory backends with "info memdev" David Hildenbrand
2021-04-21 21:05 ` Eduardo Habkost
2021-04-23 11:16 ` Markus Armbruster
2021-04-21 21:06 ` Eduardo Habkost [this message]
2021-04-23 10:35 ` [PATCH v6 00/15] RAM_NORESERVE, MAP_NORESERVE and hostmem "reserve" property David Hildenbrand
2021-04-28 16:35 ` Eduardo Habkost
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