Allows to disable memory merge support (KSM on Linux), which is enabled
by default otherwise.
Signed-off-by: Luiz Capitulino <lcapitul...@redhat.com>
---
exec.c | 19 ++++++++++++++++---
qemu-config.c | 4 ++++
qemu-options.hx | 5 ++++-
3 files changed, 24 insertions(+), 4 deletions(-)
diff --git a/exec.c b/exec.c
index 8244d54..24dd154 100644
--- a/exec.c
+++ b/exec.c
@@ -2499,6 +2499,19 @@ void qemu_ram_set_idstr(ram_addr_t addr, const char
*name, DeviceState *dev)
}
}
+static int madvise_mergeable(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)
{
@@ -2518,7 +2531,7 @@ 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);
+ madvise_mergeable(new_block->host, size);
}
#else
fprintf(stderr, "-mem-path option unsupported\n");
@@ -2545,7 +2558,7 @@ ram_addr_t qemu_ram_alloc_from_ptr(ram_addr_t size, void
*host,
new_block->host = qemu_vmalloc(size);
}
#endif
- qemu_madvise(new_block->host, size, QEMU_MADV_MERGEABLE);
+ madvise_mergeable(new_block->host, size);
}
}
new_block->length = size;
@@ -2672,7 +2685,7 @@ void qemu_ram_remap(ram_addr_t addr, ram_addr_t length)
length, addr);
exit(1);
}
- qemu_madvise(vaddr, length, QEMU_MADV_MERGEABLE);
+ madvise_mergeable(vaddr, length);
}
return;
}
diff --git a/qemu-config.c b/qemu-config.c
index 5c3296b..e47612e 100644
--- a/qemu-config.c
+++ b/qemu-config.c
@@ -595,6 +595,10 @@ static QemuOptsList qemu_machine_opts = {
.name = "dt_compatible",
.type = QEMU_OPT_STRING,
.help = "Overrides the \"compatible\" property of the dt root
node",
+ }, {
+ .name = "mem_merge",
+ .type = QEMU_OPT_BOOL,
+ .help = "enable/disable memory merge support",
},
{ /* End of list */ }
},
diff --git a/qemu-options.hx b/qemu-options.hx
index 8b66264..e0e7686 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -33,7 +33,8 @@ DEF("machine", HAS_ARG, QEMU_OPTION_machine, \
" property accel=accel1[:accel2[:...]] selects
accelerator\n"
" 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",
+ " kvm_shadow_mem=size of KVM shadow MMU\n"
+ " mem_merge=on|off controls memory merge support (default:
on)\n",
QEMU_ARCH_ALL)
STEXI
@item -machine [type=]@var{name}[,prop=@var{value}[,...]]
@@ -50,6 +51,8 @@ to initialize.
Enables in-kernel irqchip support for the chosen accelerator when available.
@item kvm_shadow_mem=size
Defines the size of the KVM shadow MMU.
+@item mem_merge=on|off
+Enables or disables memory merge support (enabled by default).
@end table
ETEXI
--
1.7.10.2.565.gbd578b5
