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add -machine mem-merge=on|off option

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It allows to disable memory merge support (KSM on Linux), which is
enabled by default otherwise.

Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
This commit is contained in:
Luiz Capitulino 2012-09-05 16:50:16 -03:00 committed by Anthony Liguori
parent 89c33337fd
commit 8490fc78e7
3 changed files with 26 additions and 4 deletions
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19
exec.c
View File

@ -2525,6 +2525,19 @@ void qemu_ram_set_idstr(ram_addr_t addr, const char *name, DeviceState *dev)
}
}
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)
{
@ -2544,7 +2557,7 @@ ram_addr_t qemu_ram_alloc_from_ptr(ram_addr_t size, void *host,
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");
@ -2559,7 +2572,7 @@ ram_addr_t qemu_ram_alloc_from_ptr(ram_addr_t size, void *host,
} 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;
@ -2689,7 +2702,7 @@ void qemu_ram_remap(ram_addr_t addr, ram_addr_t length)
length, addr);
exit(1);
}
qemu_madvise(vaddr, length, QEMU_MADV_MERGEABLE);
memory_try_enable_merging(vaddr, length);
qemu_ram_setup_dump(vaddr, length);
}
return;

4
qemu-config.c
View File

@ -615,6 +615,10 @@ static QemuOptsList qemu_machine_opts = {
.name = "dump-guest-core",
.type = QEMU_OPT_BOOL,
.help = "Include guest memory in a core dump",
}, {
.name = "mem-merge",
.type = QEMU_OPT_BOOL,
.help = "enable/disable memory merge support",
},
{ /* End of list */ }
},

7
qemu-options.hx
View File

@ -38,7 +38,8 @@ DEF("machine", HAS_ARG, QEMU_OPTION_machine, \
" 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}[,...]]
@ -57,6 +58,10 @@ Enables in-kernel irqchip support for the chosen accelerator when available.
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