[Top][All Lists]
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[Qemu-devel] [PATCH v4] add -machine mem-merge=on|off option
From: |
Luiz Capitulino |
Subject: |
[Qemu-devel] [PATCH v4] add -machine mem-merge=on|off option |
Date: |
Wed, 18 Jul 2012 11:31:16 -0300 |
It allows to disable memory merge support (KSM on Linux), which is
enabled by default otherwise.
Signed-off-by: Luiz Capitulino <address@hidden>
---
IMPORTANT: this is on top of this series:
http://lists.gnu.org/archive/html/qemu-devel/2012-07/msg01798.html
o v4
- rename option to mem-merge
- rebase on top of latest master
- rebase on top of the machine option rename series
exec.c | 19 ++++++++++++++++---
qemu-config.c | 4 ++++
qemu-options.hx | 7 ++++++-
3 files changed, 26 insertions(+), 4 deletions(-)
diff --git a/exec.c b/exec.c
index c9fa17d..59d29ae 100644
--- a/exec.c
+++ b/exec.c
@@ -2510,6 +2510,19 @@ 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)
{
@@ -2529,7 +2542,7 @@ 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");
@@ -2544,7 +2557,7 @@ 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;
@@ -2670,7 +2683,7 @@ 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);
}
return;
}
diff --git a/qemu-config.c b/qemu-config.c
index 9dac3be..3355e45 100644
--- a/qemu-config.c
+++ b/qemu-config.c
@@ -599,6 +599,10 @@ static QemuOptsList qemu_machine_opts = {
.alias= "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 90eab87..25ce07e 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 address@hidden,address@hidden,...]]
@@ -50,6 +51,10 @@ 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.
address@hidden 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
--
1.7.11.1.116.g8228a23
[Prev in Thread] |
Current Thread |
[Next in Thread] |
- [Qemu-devel] [PATCH v4] add -machine mem-merge=on|off option,
Luiz Capitulino <=