From 705b3efb8c0cf06cbf087204fc61863c2bbb9e27 Mon Sep 17 00:00:00 2001
From: Michael Tokarev <mjt@tls.msk.ru>
Date: Wed, 15 Aug 2012 18:55:16 +0400
Subject: [PATCH] mark large vmalloc areas as MADV_HUGEPAGE and allow
hugepages on i386
A followup to commit 36b586284e678d.
On linux only (which supports transparent hugepages), explicitly mark
large vmalloced areas with madvise(MADV_HUGEPAGES). The patch changes
previous logic a bit to allow inserting the call to madvise(), but keeps
the code the same (and saves one call to getpagesize() per allocation).
The code also adds #include <sys/mman.h> to the linux-specific part,
to get MADV_HUGEPAGES definition.
While at it, enable transparent hugepages (alignment and the new
explicit marking with madvise()) for 32bit x86 too - it makes good
sense for, say, 32bit userspace on 64bit kernel.
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
---
oslib-posix.c | 35 +++++++++++++++++++++++++----------
1 file changed, 25 insertions(+), 10 deletions(-)
@@ -35,19 +35,23 @@
extern int daemon(int, int);
#endif
-#if defined(__linux__) && defined(__x86_64__)
+#ifdef __linux__
+# include <sys/mman.h>
+
+# if defined(__x86_64__) || defined(__i386__)
/* Use 2 MiB alignment so transparent hugepages can be used by KVM.
Valgrind does not support alignments larger than 1 MiB,
therefore we need special code which handles running on Valgrind. */
-# define QEMU_VMALLOC_ALIGN (512 * 4096)
+# define QEMU_VMALLOC_ALIGN_HUGE (512 * 4096)
# define CONFIG_VALGRIND
-#elif defined(__linux__) && defined(__s390x__)
+# elif defined(__s390x__)
/* Use 1 MiB (segment size) alignment so gmap can be used by KVM. */
-# define QEMU_VMALLOC_ALIGN (256 * 4096)
-#else
-# define QEMU_VMALLOC_ALIGN getpagesize()
+# define QEMU_VMALLOC_ALIGN_HUGE (256 * 4096)
+# endif
#endif
+#define QEMU_VMALLOC_ALIGN getpagesize()
+
#include "config-host.h"
#include "sysemu.h"
#include "trace.h"
@@ -114,7 +118,6 @@ void *qemu_memalign(size_t alignment, size_t size)
void *qemu_vmalloc(size_t size)
{
void *ptr;
- size_t align = QEMU_VMALLOC_ALIGN;
#if defined(CONFIG_VALGRIND)
if (running_on_valgrind < 0) {
@@ -125,10 +128,22 @@ void *qemu_vmalloc(size_t size)
}
#endif
- if (size < align || running_on_valgrind) {
- align = getpagesize();
+#ifdef QEMU_VMALLOC_ALIGN_HUGE
+ /* try to allocate as huge pages if supported and large enough */
+ if (size >= QEMU_VMALLOC_ALIGN_HUGE && !running_on_valgrind) {
+ ptr = qemu_memalign(QEMU_VMALLOC_ALIGN_HUGE, size);
+#ifdef MADV_HUGEPAGE
+#error
+ qemu_madvise(ptr, size, MADV_HUGEPAGE);
+#endif
}
- ptr = qemu_memalign(align, size);
+ else
+#endif
+ {
+ /* if unsupported or small, allocate pagesize-aligned */
+ ptr = qemu_memalign(QEMU_VMALLOC_ALIGN, size);
+ }
+
trace_qemu_vmalloc(size, ptr);
return ptr;
}
--
1.7.10.4