qemu/include/sysemu/hostmem.h
David Hildenbrand e681645862 hostmem: Allow for specifying a ThreadContext for preallocation
Let's allow for specifying a thread context via the "prealloc-context"
property. When set, preallcoation threads will be crated via the
thread context -- inheriting the same CPU affinity as the thread
context.

Pinning preallcoation threads to CPUs can heavily increase performance
in NUMA setups, because, preallocation from a CPU close to the target
NUMA node(s) is faster then preallocation from a CPU further remote,
simply because of memory bandwidth for initializing memory with zeroes.
This is especially relevant for very large VMs backed by huge/gigantic
pages, whereby preallocation is mandatory.

Reviewed-by: Michal Privoznik <mprivozn@redhat.com>
Message-Id: <20221014134720.168738-7-david@redhat.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
2022-10-27 11:01:03 +02:00

86 lines
2.2 KiB
C

/*
* QEMU Host Memory Backend
*
* Copyright (C) 2013-2014 Red Hat Inc
*
* Authors:
* Igor Mammedov <imammedo@redhat.com>
*
* This work is licensed under the terms of the GNU GPL, version 2 or later.
* See the COPYING file in the top-level directory.
*/
#ifndef SYSEMU_HOSTMEM_H
#define SYSEMU_HOSTMEM_H
#include "sysemu/numa.h"
#include "qapi/qapi-types-machine.h"
#include "qom/object.h"
#include "exec/memory.h"
#include "qemu/bitmap.h"
#include "qemu/thread-context.h"
#define TYPE_MEMORY_BACKEND "memory-backend"
OBJECT_DECLARE_TYPE(HostMemoryBackend, HostMemoryBackendClass,
MEMORY_BACKEND)
/* hostmem-ram.c */
/**
* @TYPE_MEMORY_BACKEND_RAM:
* name of backend that uses mmap on the anonymous RAM
*/
#define TYPE_MEMORY_BACKEND_RAM "memory-backend-ram"
/* hostmem-file.c */
/**
* @TYPE_MEMORY_BACKEND_FILE:
* name of backend that uses mmap on a file descriptor
*/
#define TYPE_MEMORY_BACKEND_FILE "memory-backend-file"
/**
* HostMemoryBackendClass:
* @parent_class: opaque parent class container
*/
struct HostMemoryBackendClass {
ObjectClass parent_class;
void (*alloc)(HostMemoryBackend *backend, Error **errp);
};
/**
* @HostMemoryBackend
*
* @parent: opaque parent object container
* @size: amount of memory backend provides
* @mr: MemoryRegion representing host memory belonging to backend
* @prealloc_threads: number of threads to be used for preallocatining RAM
*/
struct HostMemoryBackend {
/* private */
Object parent;
/* protected */
uint64_t size;
bool merge, dump, use_canonical_path;
bool prealloc, is_mapped, share, reserve;
uint32_t prealloc_threads;
ThreadContext *prealloc_context;
DECLARE_BITMAP(host_nodes, MAX_NODES + 1);
HostMemPolicy policy;
MemoryRegion mr;
};
bool host_memory_backend_mr_inited(HostMemoryBackend *backend);
MemoryRegion *host_memory_backend_get_memory(HostMemoryBackend *backend);
void host_memory_backend_set_mapped(HostMemoryBackend *backend, bool mapped);
bool host_memory_backend_is_mapped(HostMemoryBackend *backend);
size_t host_memory_backend_pagesize(HostMemoryBackend *memdev);
char *host_memory_backend_get_name(HostMemoryBackend *backend);
#endif