diff options
| author | Avi Kivity <avi@redhat.com> | 2011-09-05 11:07:05 +0300 |
|---|---|---|
| committer | Anthony Liguori <aliguori@us.ibm.com> | 2011-09-09 12:58:16 -0500 |
| commit | 36b586284e678da28df3af9fd0907d2b16f9311c (patch) | |
| tree | 9aea538dac96f4481be4a7d3486b794546d21a72 | |
| parent | df00bed0fa30a6f5712456e7add783e470c534c9 (diff) | |
qemu_vmalloc: align properly for transparent hugepages and KVM
To make good use of transparent hugepages, KVM requires that guest-physical
and host-virtual addresses share the low 21 bits (as opposed to just the low
12 bits normally required).
Adjust qemu_vmalloc() to honor that requirement. Ignore it for small regions
to avoid fragmentation.
Signed-off-by: Avi Kivity <avi@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
| -rw-r--r-- | oslib-posix.c | 14 |
1 files changed, 13 insertions, 1 deletions
diff --git a/oslib-posix.c b/oslib-posix.c index 196099cc77..a304fb0f53 100644 --- a/oslib-posix.c +++ b/oslib-posix.c @@ -35,6 +35,13 @@ extern int daemon(int, int); #endif +#if defined(__linux__) && defined(__x86_64__) + /* Use 2MB alignment so transparent hugepages can be used by KVM */ +# define QEMU_VMALLOC_ALIGN (512 * 4096) +#else +# define QEMU_VMALLOC_ALIGN getpagesize() +#endif + #include "config-host.h" #include "sysemu.h" #include "trace.h" @@ -80,7 +87,12 @@ void *qemu_memalign(size_t alignment, size_t size) void *qemu_vmalloc(size_t size) { void *ptr; - ptr = qemu_memalign(getpagesize(), size); + size_t align = QEMU_VMALLOC_ALIGN; + + if (size < align) { + align = getpagesize(); + } + ptr = qemu_memalign(align, size); trace_qemu_vmalloc(size, ptr); return ptr; } |