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kvm: port qemu-kvm's bitmap scanning

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Which is significantly faster.

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
This commit is contained in:
Marcelo Tosatti 2010-04-23 14:04:14 -03:00
parent 213acd2ec2
commit 8369e01ce4
1 changed files with 37 additions and 16 deletions
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53
kvm-all.c
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@ -26,6 +26,7 @@
#include "hw/hw.h"
#include "gdbstub.h"
#include "kvm.h"
#include "bswap.h"
/* KVM uses PAGE_SIZE in it's definition of COALESCED_MMIO_MAX */
#define PAGE_SIZE TARGET_PAGE_SIZE
@ -283,11 +284,41 @@ static int kvm_set_migration_log(int enable)
return 0;
}
static int test_le_bit(unsigned long nr, unsigned char *addr)
/* get kvm's dirty pages bitmap and update qemu's */
static int kvm_get_dirty_pages_log_range(unsigned long start_addr,
unsigned long *bitmap,
unsigned long offset,
unsigned long mem_size)
{
return (addr[nr >> 3] >> (nr & 7)) & 1;
unsigned int i, j;
unsigned long page_number, addr, addr1, c;
ram_addr_t ram_addr;
unsigned int len = ((mem_size / TARGET_PAGE_SIZE) + HOST_LONG_BITS - 1) /
HOST_LONG_BITS;
/*
* bitmap-traveling is faster than memory-traveling (for addr...)
* especially when most of the memory is not dirty.
*/
for (i = 0; i < len; i++) {
if (bitmap[i] != 0) {
c = leul_to_cpu(bitmap[i]);
do {
j = ffsl(c) - 1;
c &= ~(1ul << j);
page_number = i * HOST_LONG_BITS + j;
addr1 = page_number * TARGET_PAGE_SIZE;
addr = offset + addr1;
ram_addr = cpu_get_physical_page_desc(addr);
cpu_physical_memory_set_dirty(ram_addr);
} while (c != 0);
}
}
return 0;
}
#define ALIGN(x, y) (((x)+(y)-1) & ~((y)-1))
/**
* kvm_physical_sync_dirty_bitmap - Grab dirty bitmap from kernel space
* This function updates qemu's dirty bitmap using cpu_physical_memory_set_dirty().
@ -301,8 +332,6 @@ static int kvm_physical_sync_dirty_bitmap(target_phys_addr_t start_addr,
{
KVMState *s = kvm_state;
unsigned long size, allocated_size = 0;
target_phys_addr_t phys_addr;
ram_addr_t addr;
KVMDirtyLog d;
KVMSlot *mem;
int ret = 0;
@ -314,7 +343,7 @@ static int kvm_physical_sync_dirty_bitmap(target_phys_addr_t start_addr,
break;
}
size = ((mem->memory_size >> TARGET_PAGE_BITS) + 7) / 8;
size = ALIGN(((mem->memory_size) >> TARGET_PAGE_BITS), HOST_LONG_BITS) / 8;
if (!d.dirty_bitmap) {
d.dirty_bitmap = qemu_malloc(size);
} else if (size > allocated_size) {
@ -331,17 +360,9 @@ static int kvm_physical_sync_dirty_bitmap(target_phys_addr_t start_addr,
break;
}
for (phys_addr = mem->start_addr, addr = mem->phys_offset;
phys_addr < mem->start_addr + mem->memory_size;
phys_addr += TARGET_PAGE_SIZE, addr += TARGET_PAGE_SIZE) {
unsigned char *bitmap = (unsigned char *)d.dirty_bitmap;
unsigned nr = (phys_addr - mem->start_addr) >> TARGET_PAGE_BITS;
if (test_le_bit(nr, bitmap)) {
cpu_physical_memory_set_dirty(addr);
}
}
start_addr = phys_addr;
kvm_get_dirty_pages_log_range(mem->start_addr, d.dirty_bitmap,
mem->start_addr, mem->memory_size);
start_addr = mem->start_addr + mem->memory_size;
}
qemu_free(d.dirty_bitmap);