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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-changelog] [xen-unstable] xmalloc: make close-to-PAGE_SIZE allocations more efficient
# HG changeset patch
# User Jan Beulich <jbeulich@xxxxxxxx>
# Date 1361267393 -3600
# Node ID 66f563be41d90b480eb99e3e842d4e9ab260861c
# Parent 620e5d3aa7cd0b513125bf1f4270aa29daea9d69
xmalloc: make close-to-PAGE_SIZE allocations more efficient
Rather than bumping their sizes to slightly above (a multiple of)
PAGE_SIZE (in order to store tracking information), thus requiring
a non-order-0 allocation even when no more than a page is being
requested, return the result of alloc_xenheap_pages() directly, and use
the struct page_info field underlying PFN_ORDER() to store the actual
size (needed for freeing the memory).
This leverages the fact that sub-allocation of memory obtained from the
page allocator can only ever result in non-page-aligned memory chunks
(with the exception of zero size allocations with sufficiently high
alignment being requested, which is why zero-size allocations now get
special cased).
Use the new property to simplify allocation of the trap info array for
PV guests on x86.
Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
Acked-by: Keir Fraser <keir@xxxxxxx>
---
diff -r 620e5d3aa7cd -r 66f563be41d9 xen/arch/x86/domain.c
--- a/xen/arch/x86/domain.c Mon Feb 18 09:38:25 2013 +0100
+++ b/xen/arch/x86/domain.c Tue Feb 19 10:49:53 2013 +0100
@@ -369,13 +369,6 @@ int switch_compat(struct domain *d)
return -ENOMEM;
}
-static inline bool_t standalone_trap_ctxt(struct vcpu *v)
-{
- BUILD_BUG_ON(NR_VECTORS * sizeof(*v->arch.pv_vcpu.trap_ctxt) > PAGE_SIZE);
- return NR_VECTORS * sizeof(*v->arch.pv_vcpu.trap_ctxt) + sizeof(*v)
- > PAGE_SIZE;
-}
-
int vcpu_initialise(struct vcpu *v)
{
struct domain *d = v->domain;
@@ -427,19 +420,15 @@ int vcpu_initialise(struct vcpu *v)
if ( !is_idle_domain(d) )
{
- if ( standalone_trap_ctxt(v) )
+ BUILD_BUG_ON(NR_VECTORS * sizeof(*v->arch.pv_vcpu.trap_ctxt) >
+ PAGE_SIZE);
+ v->arch.pv_vcpu.trap_ctxt = xzalloc_array(struct trap_info,
+ NR_VECTORS);
+ if ( !v->arch.pv_vcpu.trap_ctxt )
{
- v->arch.pv_vcpu.trap_ctxt = alloc_xenheap_page();
- if ( !v->arch.pv_vcpu.trap_ctxt )
- {
- rc = -ENOMEM;
- goto done;
- }
- clear_page(v->arch.pv_vcpu.trap_ctxt);
+ rc = -ENOMEM;
+ goto done;
}
- else
- v->arch.pv_vcpu.trap_ctxt = (void *)v + PAGE_SIZE -
- NR_VECTORS * sizeof(*v->arch.pv_vcpu.trap_ctxt);
/* PV guests by default have a 100Hz ticker. */
v->periodic_period = MILLISECS(10);
@@ -467,8 +456,8 @@ int vcpu_initialise(struct vcpu *v)
{
vcpu_destroy_fpu(v);
- if ( !is_hvm_domain(d) && standalone_trap_ctxt(v) )
- free_xenheap_page(v->arch.pv_vcpu.trap_ctxt);
+ if ( !is_hvm_domain(d) )
+ xfree(v->arch.pv_vcpu.trap_ctxt);
}
return rc;
@@ -483,8 +472,8 @@ void vcpu_destroy(struct vcpu *v)
if ( is_hvm_vcpu(v) )
hvm_vcpu_destroy(v);
- else if ( standalone_trap_ctxt(v) )
- free_xenheap_page(v->arch.pv_vcpu.trap_ctxt);
+ else
+ xfree(v->arch.pv_vcpu.trap_ctxt);
}
int arch_domain_create(struct domain *d, unsigned int domcr_flags)
diff -r 620e5d3aa7cd -r 66f563be41d9 xen/common/xmalloc_tlsf.c
--- a/xen/common/xmalloc_tlsf.c Mon Feb 18 09:38:25 2013 +0100
+++ b/xen/common/xmalloc_tlsf.c Tue Feb 19 10:49:53 2013 +0100
@@ -26,6 +26,7 @@
#include <xen/config.h>
#include <xen/irq.h>
#include <xen/mm.h>
+#include <xen/pfn.h>
#include <asm/time.h>
#define MAX_POOL_NAME_LEN 16
@@ -524,25 +525,30 @@ static void xmalloc_pool_put(void *p)
free_xenheap_page(p);
}
-static void *xmalloc_whole_pages(unsigned long size)
+static void *xmalloc_whole_pages(unsigned long size, unsigned long align)
{
- struct bhdr *b;
- unsigned int i, pageorder = get_order_from_bytes(size + BHDR_OVERHEAD);
- char *p;
+ unsigned int i, order = get_order_from_bytes(size);
+ void *res, *p;
- b = alloc_xenheap_pages(pageorder, 0);
- if ( b == NULL )
+ if ( align > size )
+ get_order_from_bytes(align);
+
+ res = alloc_xenheap_pages(order, 0);
+ if ( res == NULL )
return NULL;
- b->size = PAGE_ALIGN(size + BHDR_OVERHEAD);
- for ( p = (char *)b + b->size, i = 0; i < pageorder; ++i )
+ for ( p = res + PAGE_ALIGN(size), i = 0; i < order; ++i )
if ( (unsigned long)p & (PAGE_SIZE << i) )
{
free_xenheap_pages(p, i);
p += PAGE_SIZE << i;
}
- return (void *)b->ptr.buffer;
+ PFN_ORDER(virt_to_page(res)) = PFN_UP(size);
+ /* Check that there was no truncation: */
+ ASSERT(PFN_ORDER(virt_to_page(res)) == PFN_UP(size));
+
+ return res;
}
static void tlsf_init(void)
@@ -559,6 +565,11 @@ static void tlsf_init(void)
* xmalloc()
*/
+#ifndef ZERO_BLOCK_PTR
+/* Return value for zero-size allocation, distinguished from NULL. */
+#define ZERO_BLOCK_PTR ((void *)-1L)
+#endif
+
void *_xmalloc(unsigned long size, unsigned long align)
{
void *p = NULL;
@@ -566,6 +577,9 @@ void *_xmalloc(unsigned long size, unsig
ASSERT(!in_irq());
+ if ( !size )
+ return ZERO_BLOCK_PTR;
+
ASSERT((align & (align - 1)) == 0);
if ( align < MEM_ALIGN )
align = MEM_ALIGN;
@@ -577,7 +591,7 @@ void *_xmalloc(unsigned long size, unsig
if ( size < PAGE_SIZE )
p = xmem_pool_alloc(size, xenpool);
if ( p == NULL )
- p = xmalloc_whole_pages(size);
+ return xmalloc_whole_pages(size - align + MEM_ALIGN, align);
/* Add alignment padding. */
if ( (pad = -(long)p & (align - 1)) != 0 )
@@ -604,11 +618,28 @@ void xfree(void *p)
{
struct bhdr *b;
- if ( p == NULL )
+ if ( p == NULL || p == ZERO_BLOCK_PTR )
return;
ASSERT(!in_irq());
+ if ( !((unsigned long)p & (PAGE_SIZE - 1)) )
+ {
+ unsigned long size = PFN_ORDER(virt_to_page(p));
+ unsigned int i, order = get_order_from_pages(size);
+
+ BUG_ON((unsigned long)p & ((PAGE_SIZE << order) - 1));
+ for ( i = 0; ; ++i )
+ {
+ if ( !(size & (1 << i)) )
+ continue;
+ size -= 1 << i;
+ free_xenheap_pages(p + (size << PAGE_SHIFT), i);
+ if ( i + 1 >= order )
+ return;
+ }
+ }
+
/* Strip alignment padding. */
b = (struct bhdr *)((char *) p - BHDR_OVERHEAD);
if ( b->size & 1 )
@@ -618,21 +649,5 @@ void xfree(void *p)
ASSERT(!(b->size & 1));
}
- if ( b->size >= PAGE_SIZE )
- {
- unsigned int i, order = get_order_from_bytes(b->size);
-
- BUG_ON((unsigned long)b & ((PAGE_SIZE << order) - 1));
- for ( i = 0; ; ++i )
- {
- if ( !(b->size & (PAGE_SIZE << i)) )
- continue;
- b->size -= PAGE_SIZE << i;
- free_xenheap_pages((void *)b + b->size, i);
- if ( i + 1 >= order )
- break;
- }
- }
- else
- xmem_pool_free(p, xenpool);
+ xmem_pool_free(p, xenpool);
}
diff -r 620e5d3aa7cd -r 66f563be41d9 xen/include/asm-x86/config.h
--- a/xen/include/asm-x86/config.h Mon Feb 18 09:38:25 2013 +0100
+++ b/xen/include/asm-x86/config.h Tue Feb 19 10:49:53 2013 +0100
@@ -91,6 +91,9 @@
/* Primary stack is restricted to 8kB by guard pages. */
#define PRIMARY_STACK_SIZE 8192
+/* Return value for zero-size _xmalloc(), distinguished from NULL. */
+#define ZERO_BLOCK_PTR ((void *)0xBAD0BAD0BAD0BAD0UL)
+
#ifndef __ASSEMBLY__
extern unsigned long trampoline_phys;
#define bootsym_phys(sym) \
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