}
}
+static int memory_try_enable_merging(void *addr, size_t len)
+{
+ QemuOpts *opts;
+
+ opts = qemu_opts_find(qemu_find_opts("machine"), 0);
+ if (opts && !qemu_opt_get_bool(opts, "mem-merge", true)) {
+ /* disabled by the user */
+ return 0;
+ }
+
+ return qemu_madvise(addr, len, QEMU_MADV_MERGEABLE);
+}
+
ram_addr_t qemu_ram_alloc_from_ptr(ram_addr_t size, void *host,
MemoryRegion *mr)
{
new_block->host = file_ram_alloc(new_block, size, mem_path);
if (!new_block->host) {
new_block->host = qemu_vmalloc(size);
- qemu_madvise(new_block->host, size, QEMU_MADV_MERGEABLE);
+ memory_try_enable_merging(new_block->host, size);
}
#else
fprintf(stderr, "-mem-path option unsupported\n");
} else {
new_block->host = qemu_vmalloc(size);
}
- qemu_madvise(new_block->host, size, QEMU_MADV_MERGEABLE);
+ memory_try_enable_merging(new_block->host, size);
}
}
new_block->length = size;
length, addr);
exit(1);
}
- qemu_madvise(vaddr, length, QEMU_MADV_MERGEABLE);
+ memory_try_enable_merging(vaddr, length);
qemu_ram_setup_dump(vaddr, length);
}
return;
" supported accelerators are kvm, xen, tcg (default: tcg)\n"
" kernel_irqchip=on|off controls accelerated irqchip support\n"
" kvm_shadow_mem=size of KVM shadow MMU\n"
- " dump-guest-core=on|off include guest memory in a core dump (default=on)\n",
+ " dump-guest-core=on|off include guest memory in a core dump (default=on)\n"
+ " mem-merge=on|off controls memory merge support (default: on)\n",
QEMU_ARCH_ALL)
STEXI
@item -machine [type=]@var{name}[,prop=@var{value}[,...]]
Defines the size of the KVM shadow MMU.
@item dump-guest-core=on|off
Include guest memory in a core dump. The default is on.
+@item mem-merge=on|off
+Enables or disables memory merge support. This feature, when supported by
+the host, de-duplicates identical memory pages among VMs instances
+(enabled by default).
@end table
ETEXI