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migration: convert post-copy to use QIOChannelBuffer 

The post-copy code does some I/O to/from an intermediate
in-memory buffer rather than direct to the underlying
I/O channel. Switch this code to use QIOChannelBuffer
instead of QEMUSizedBuffer.

Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Message-Id: <1461751518-12128-12-git-send-email-berrange@redhat.com>
Signed-off-by: Amit Shah <amit.shah@redhat.com>
This commit is contained in:
Daniel P. Berrange 2016-04-27 11:05:01 +01:00 committed by Amit Shah
parent d59ce6f344
commit 61b67d473d
4 changed files with 26 additions and 42 deletions
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4
docs/migration.txt
View File

@ -403,8 +403,8 @@ listen thread: --- page -- page -- page -- page -- page --
On receipt of CMD_PACKAGED (1)
All the data associated with the package - the ( ... ) section in the
diagram - is read into memory (into a QEMUSizedBuffer), and the main thread
recurses into qemu_loadvm_state_main to process the contents of the package (2)
diagram - is read into memory, and the main thread recurses into
qemu_loadvm_state_main to process the contents of the package (2)
which contains commands (3,6) and devices (4...)
On receipt of 'postcopy listen' - 3 -(i.e. the 1st command in the package)

2
include/sysemu/sysemu.h
View File

@ -119,7 +119,7 @@ void qemu_savevm_command_send(QEMUFile *f, enum qemu_vm_cmd command,
uint16_t len, uint8_t *data);
void qemu_savevm_send_ping(QEMUFile *f, uint32_t value);
void qemu_savevm_send_open_return_path(QEMUFile *f);
int qemu_savevm_send_packaged(QEMUFile *f, const QEMUSizedBuffer *qsb);
int qemu_savevm_send_packaged(QEMUFile *f, const uint8_t *buf, size_t len);
void qemu_savevm_send_postcopy_advise(QEMUFile *f);
void qemu_savevm_send_postcopy_listen(QEMUFile *f);
void qemu_savevm_send_postcopy_run(QEMUFile *f);

15
migration/migration.c
View File

@ -34,6 +34,7 @@
#include "qom/cpu.h"
#include "exec/memory.h"
#include "exec/address-spaces.h"
#include "io/channel-buffer.h"
#define MAX_THROTTLE (32 << 20) /* Migration transfer speed throttling */
@ -1457,7 +1458,8 @@ static int await_return_path_close_on_source(MigrationState *ms)
static int postcopy_start(MigrationState *ms, bool *old_vm_running)
{
int ret;
const QEMUSizedBuffer *qsb;
QIOChannelBuffer *bioc;
QEMUFile *fb;
int64_t time_at_stop = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
migrate_set_state(&ms->state, MIGRATION_STATUS_ACTIVE,
MIGRATION_STATUS_POSTCOPY_ACTIVE);
@ -1516,11 +1518,9 @@ static int postcopy_start(MigrationState *ms, bool *old_vm_running)
* So we wrap the device state up in a package with a length at the start;
* to do this we use a qemu_buf to hold the whole of the device state.
*/
QEMUFile *fb = qemu_bufopen("w", NULL);
if (!fb) {
error_report("Failed to create buffered file");
goto fail;
}
bioc = qio_channel_buffer_new(4096);
fb = qemu_fopen_channel_output(QIO_CHANNEL(bioc));
object_unref(OBJECT(bioc));
/*
* Make sure the receiver can get incoming pages before we send the rest
@ -1534,10 +1534,9 @@ static int postcopy_start(MigrationState *ms, bool *old_vm_running)
qemu_savevm_send_postcopy_run(fb);
/* <><> end of stuff going into the package */
qsb = qemu_buf_get(fb);
/* Now send that blob */
if (qemu_savevm_send_packaged(ms->to_dst_file, qsb)) {
if (qemu_savevm_send_packaged(ms->to_dst_file, bioc->data, bioc->usage)) {
goto fail_closefb;
}
qemu_fclose(fb);

47
migration/savevm.c
View File

@ -51,6 +51,7 @@
#include "block/snapshot.h"
#include "block/qapi.h"
#include "qemu/cutils.h"
#include "io/channel-buffer.h"
#ifndef ETH_P_RARP
#define ETH_P_RARP 0x8035
@ -760,10 +761,8 @@ void qemu_savevm_send_open_return_path(QEMUFile *f)
* 0 on success
* -ve on error
*/
int qemu_savevm_send_packaged(QEMUFile *f, const QEMUSizedBuffer *qsb)
int qemu_savevm_send_packaged(QEMUFile *f, const uint8_t *buf, size_t len)
{
size_t cur_iov;
size_t len = qsb_get_length(qsb);
uint32_t tmp;
if (len > MAX_VM_CMD_PACKAGED_SIZE) {
@ -777,18 +776,7 @@ int qemu_savevm_send_packaged(QEMUFile *f, const QEMUSizedBuffer *qsb)
trace_qemu_savevm_send_packaged();
qemu_savevm_command_send(f, MIG_CMD_PACKAGED, 4, (uint8_t *)&tmp);
/* all the data follows (concatinating the iov's) */
for (cur_iov = 0; cur_iov < qsb->n_iov; cur_iov++) {
/* The iov entries are partially filled */
size_t towrite = MIN(qsb->iov[cur_iov].iov_len, len);
len -= towrite;
if (!towrite) {
break;
}
qemu_put_buffer(f, qsb->iov[cur_iov].iov_base, towrite);
}
qemu_put_buffer(f, buf, len);
return 0;
}
@ -1578,39 +1566,36 @@ static int loadvm_postcopy_handle_run(MigrationIncomingState *mis)
static int loadvm_handle_cmd_packaged(MigrationIncomingState *mis)
{
int ret;
uint8_t *buffer;
uint32_t length;
QEMUSizedBuffer *qsb;
size_t length;
QIOChannelBuffer *bioc;
length = qemu_get_be32(mis->from_src_file);
trace_loadvm_handle_cmd_packaged(length);
if (length > MAX_VM_CMD_PACKAGED_SIZE) {
error_report("Unreasonably large packaged state: %u", length);
error_report("Unreasonably large packaged state: %zu", length);
return -1;
}
buffer = g_malloc0(length);
ret = qemu_get_buffer(mis->from_src_file, buffer, (int)length);
bioc = qio_channel_buffer_new(length);
ret = qemu_get_buffer(mis->from_src_file,
bioc->data,
length);
if (ret != length) {
g_free(buffer);
error_report("CMD_PACKAGED: Buffer receive fail ret=%d length=%d",
object_unref(OBJECT(bioc));
error_report("CMD_PACKAGED: Buffer receive fail ret=%d length=%zu",
ret, length);
return (ret < 0) ? ret : -EAGAIN;
}
bioc->usage += length;
trace_loadvm_handle_cmd_packaged_received(ret);
/* Setup a dummy QEMUFile that actually reads from the buffer */
qsb = qsb_create(buffer, length);
g_free(buffer); /* Because qsb_create copies */
if (!qsb) {
error_report("Unable to create qsb");
}
QEMUFile *packf = qemu_bufopen("r", qsb);
QEMUFile *packf = qemu_fopen_channel_input(QIO_CHANNEL(bioc));
ret = qemu_loadvm_state_main(packf, mis);
trace_loadvm_handle_cmd_packaged_main(ret);
qemu_fclose(packf);
qsb_free(qsb);
object_unref(OBJECT(bioc));
return ret;
}