qemu/buffered_file.c
lirans@il.ibm.com c163b5cae9 Block live migration
This patch introduces block migration called during live migration. Block
are being copied to the destination in an async way. First the code will
transfer the whole disk and then transfer all dirty blocks accumulted during
the migration.
Still need to improve transition from the iterative phase of migration to the
end phase. For now transition will take place when all blocks transfered once,
all the dirty blocks will be transfered during the end phase (guest is
suspended).

Changes from v4:
- Global variabels moved to a global state structure allocated dynamically.
- Minor coding style issues.
- Poll block.c for tracking of dirty blocks instead of manage it here.

Signed-off-by: Liran Schour <lirans@il.ibm.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
2009-11-17 08:49:30 -06:00

270 lines
6.1 KiB
C

/*
* QEMU buffered QEMUFile
*
* Copyright IBM, Corp. 2008
*
* Authors:
* Anthony Liguori <aliguori@us.ibm.com>
*
* This work is licensed under the terms of the GNU GPL, version 2. See
* the COPYING file in the top-level directory.
*
*/
#include "qemu-common.h"
#include "hw/hw.h"
#include "qemu-timer.h"
#include "sysemu.h"
#include "qemu-char.h"
#include "buffered_file.h"
//#define DEBUG_BUFFERED_FILE
typedef struct QEMUFileBuffered
{
BufferedPutFunc *put_buffer;
BufferedPutReadyFunc *put_ready;
BufferedWaitForUnfreezeFunc *wait_for_unfreeze;
BufferedCloseFunc *close;
void *opaque;
QEMUFile *file;
int has_error;
int freeze_output;
size_t bytes_xfer;
size_t xfer_limit;
uint8_t *buffer;
size_t buffer_size;
size_t buffer_capacity;
QEMUTimer *timer;
} QEMUFileBuffered;
#ifdef DEBUG_BUFFERED_FILE
#define dprintf(fmt, ...) \
do { printf("buffered-file: " fmt, ## __VA_ARGS__); } while (0)
#else
#define dprintf(fmt, ...) \
do { } while (0)
#endif
static void buffered_append(QEMUFileBuffered *s,
const uint8_t *buf, size_t size)
{
if (size > (s->buffer_capacity - s->buffer_size)) {
void *tmp;
dprintf("increasing buffer capacity from %zu by %zu\n",
s->buffer_capacity, size + 1024);
s->buffer_capacity += size + 1024;
tmp = qemu_realloc(s->buffer, s->buffer_capacity);
if (tmp == NULL) {
fprintf(stderr, "qemu file buffer expansion failed\n");
exit(1);
}
s->buffer = tmp;
}
memcpy(s->buffer + s->buffer_size, buf, size);
s->buffer_size += size;
}
static void buffered_flush(QEMUFileBuffered *s)
{
size_t offset = 0;
if (s->has_error) {
dprintf("flush when error, bailing\n");
return;
}
dprintf("flushing %zu byte(s) of data\n", s->buffer_size);
while (offset < s->buffer_size) {
ssize_t ret;
ret = s->put_buffer(s->opaque, s->buffer + offset,
s->buffer_size - offset);
if (ret == -EAGAIN) {
dprintf("backend not ready, freezing\n");
s->freeze_output = 1;
break;
}
if (ret <= 0) {
dprintf("error flushing data, %zd\n", ret);
s->has_error = 1;
break;
} else {
dprintf("flushed %zd byte(s)\n", ret);
offset += ret;
}
}
dprintf("flushed %zu of %zu byte(s)\n", offset, s->buffer_size);
memmove(s->buffer, s->buffer + offset, s->buffer_size - offset);
s->buffer_size -= offset;
}
static int buffered_put_buffer(void *opaque, const uint8_t *buf, int64_t pos, int size)
{
QEMUFileBuffered *s = opaque;
int offset = 0;
ssize_t ret;
dprintf("putting %d bytes at %" PRId64 "\n", size, pos);
if (s->has_error) {
dprintf("flush when error, bailing\n");
return -EINVAL;
}
dprintf("unfreezing output\n");
s->freeze_output = 0;
buffered_flush(s);
while (!s->freeze_output && offset < size) {
if (s->bytes_xfer > s->xfer_limit) {
dprintf("transfer limit exceeded when putting\n");
break;
}
ret = s->put_buffer(s->opaque, buf + offset, size - offset);
if (ret == -EAGAIN) {
dprintf("backend not ready, freezing\n");
s->freeze_output = 1;
break;
}
if (ret <= 0) {
dprintf("error putting\n");
s->has_error = 1;
offset = -EINVAL;
break;
}
dprintf("put %zd byte(s)\n", ret);
offset += ret;
s->bytes_xfer += ret;
}
if (offset >= 0) {
dprintf("buffering %d bytes\n", size - offset);
buffered_append(s, buf + offset, size - offset);
offset = size;
}
return offset;
}
static int buffered_close(void *opaque)
{
QEMUFileBuffered *s = opaque;
int ret;
dprintf("closing\n");
while (!s->has_error && s->buffer_size) {
buffered_flush(s);
if (s->freeze_output)
s->wait_for_unfreeze(s);
}
ret = s->close(s->opaque);
qemu_del_timer(s->timer);
qemu_free_timer(s->timer);
qemu_free(s->buffer);
qemu_free(s);
return ret;
}
static int buffered_rate_limit(void *opaque)
{
QEMUFileBuffered *s = opaque;
if (s->has_error)
return 0;
if (s->freeze_output)
return 1;
if (s->bytes_xfer > s->xfer_limit)
return 1;
return 0;
}
static size_t buffered_set_rate_limit(void *opaque, size_t new_rate)
{
QEMUFileBuffered *s = opaque;
if (s->has_error)
goto out;
s->xfer_limit = new_rate / 10;
out:
return s->xfer_limit;
}
static size_t buffered_get_rate_limit(void *opaque)
{
QEMUFileBuffered *s = opaque;
return s->xfer_limit;
}
static void buffered_rate_tick(void *opaque)
{
QEMUFileBuffered *s = opaque;
if (s->has_error)
return;
qemu_mod_timer(s->timer, qemu_get_clock(rt_clock) + 100);
if (s->freeze_output)
return;
s->bytes_xfer = 0;
buffered_flush(s);
/* Add some checks around this */
s->put_ready(s->opaque);
}
QEMUFile *qemu_fopen_ops_buffered(void *opaque,
size_t bytes_per_sec,
BufferedPutFunc *put_buffer,
BufferedPutReadyFunc *put_ready,
BufferedWaitForUnfreezeFunc *wait_for_unfreeze,
BufferedCloseFunc *close)
{
QEMUFileBuffered *s;
s = qemu_mallocz(sizeof(*s));
s->opaque = opaque;
s->xfer_limit = bytes_per_sec / 10;
s->put_buffer = put_buffer;
s->put_ready = put_ready;
s->wait_for_unfreeze = wait_for_unfreeze;
s->close = close;
s->file = qemu_fopen_ops(s, buffered_put_buffer, NULL,
buffered_close, buffered_rate_limit,
buffered_set_rate_limit,
buffered_get_rate_limit);
s->timer = qemu_new_timer(rt_clock, buffered_rate_tick, s);
qemu_mod_timer(s->timer, qemu_get_clock(rt_clock) + 100);
return s->file;
}