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Try not to exceed max downtime on stage3
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Move to stage3 only when remaining work can be done below max downtime.
Use qemu_get_clock_ns for measuring read performance.

Signed-off-by: Liran Schour <lirans@il.ibm.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
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@liranschour
liranschour authored and Anthony Liguori committed Feb 9, 2010
1 parent aaa0eb7 commit 889ae39
Showing 1 changed file with 70 additions and 9 deletions.
79 changes: 70 additions & 9 deletions block-migration.c
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Original file line number Diff line number Diff line change
Expand Up @@ -15,8 +15,10 @@
#include "block_int.h"
#include "hw/hw.h"
#include "qemu-queue.h"
#include "qemu-timer.h"
#include "monitor.h"
#include "block-migration.h"
#include "migration.h"
#include <assert.h>

#define BLOCK_SIZE (BDRV_SECTORS_PER_DIRTY_CHUNK << BDRV_SECTOR_BITS)
Expand Down Expand Up @@ -57,6 +59,7 @@ typedef struct BlkMigBlock {
QEMUIOVector qiov;
BlockDriverAIOCB *aiocb;
int ret;
int64_t time;
QSIMPLEQ_ENTRY(BlkMigBlock) entry;
} BlkMigBlock;

Expand All @@ -71,7 +74,8 @@ typedef struct BlkMigState {
int64_t total_sector_sum;
int prev_progress;
int bulk_completed;
int dirty_iterations;
long double total_time;
int reads;
} BlkMigState;

static BlkMigState block_mig_state;
Expand Down Expand Up @@ -124,12 +128,28 @@ uint64_t blk_mig_bytes_total(void)
return sum << BDRV_SECTOR_BITS;
}

static inline void add_avg_read_time(int64_t time)
{
block_mig_state.reads++;
block_mig_state.total_time += time;
}

static inline long double compute_read_bwidth(void)
{
assert(block_mig_state.total_time != 0);
return (block_mig_state.reads * BLOCK_SIZE)/ block_mig_state.total_time;
}

static void blk_mig_read_cb(void *opaque, int ret)
{
BlkMigBlock *blk = opaque;

blk->ret = ret;

blk->time = qemu_get_clock_ns(rt_clock) - blk->time;

add_avg_read_time(blk->time);

QSIMPLEQ_INSERT_TAIL(&block_mig_state.blk_list, blk, entry);

block_mig_state.submitted--;
Expand Down Expand Up @@ -179,6 +199,8 @@ static int mig_save_device_bulk(Monitor *mon, QEMUFile *f,
blk->iov.iov_len = nr_sectors * BDRV_SECTOR_SIZE;
qemu_iovec_init_external(&blk->qiov, &blk->iov, 1);

blk->time = qemu_get_clock_ns(rt_clock);

blk->aiocb = bdrv_aio_readv(bs, cur_sector, &blk->qiov,
nr_sectors, blk_mig_read_cb, blk);
if (!blk->aiocb) {
Expand Down Expand Up @@ -220,6 +242,8 @@ static void init_blk_migration(Monitor *mon, QEMUFile *f)
block_mig_state.total_sector_sum = 0;
block_mig_state.prev_progress = -1;
block_mig_state.bulk_completed = 0;
block_mig_state.total_time = 0;
block_mig_state.reads = 0;

for (bs = bdrv_first; bs != NULL; bs = bs->next) {
if (bs->type == BDRV_TYPE_HD) {
Expand Down Expand Up @@ -314,11 +338,13 @@ static int mig_save_device_dirty(Monitor *mon, QEMUFile *f,
blk->bmds = bmds;
blk->sector = sector;

if(is_async) {
if (is_async) {
blk->iov.iov_base = blk->buf;
blk->iov.iov_len = nr_sectors * BDRV_SECTOR_SIZE;
qemu_iovec_init_external(&blk->qiov, &blk->iov, 1);

blk->time = qemu_get_clock_ns(rt_clock);

blk->aiocb = bdrv_aio_readv(bmds->bs, sector, &blk->qiov,
nr_sectors, blk_mig_read_cb, blk);
if (!blk->aiocb) {
Expand All @@ -345,7 +371,7 @@ static int mig_save_device_dirty(Monitor *mon, QEMUFile *f,

return (bmds->cur_dirty >= bmds->total_sectors);

error:
error:
monitor_printf(mon, "Error reading sector %" PRId64 "\n", sector);
qemu_file_set_error(f);
qemu_free(blk->buf);
Expand All @@ -359,7 +385,7 @@ static int blk_mig_save_dirty_block(Monitor *mon, QEMUFile *f, int is_async)
int ret = 0;

QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
if(mig_save_device_dirty(mon, f, bmds, is_async) == 0) {
if (mig_save_device_dirty(mon, f, bmds, is_async) == 0) {
ret = 1;
break;
}
Expand Down Expand Up @@ -400,9 +426,42 @@ static void flush_blks(QEMUFile* f)
block_mig_state.transferred);
}

static int64_t get_remaining_dirty(void)
{
BlkMigDevState *bmds;
int64_t dirty = 0;

QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
dirty += bdrv_get_dirty_count(bmds->bs);
}

return dirty * BLOCK_SIZE;
}

static int is_stage2_completed(void)
{
return (block_mig_state.submitted == 0 && block_mig_state.bulk_completed);
int64_t remaining_dirty;
long double bwidth;

if (block_mig_state.bulk_completed == 1) {

remaining_dirty = get_remaining_dirty();
if (remaining_dirty == 0) {
return 1;
}

bwidth = compute_read_bwidth();

if ((remaining_dirty / bwidth) <=
migrate_max_downtime()) {
/* finish stage2 because we think that we can finish remaing work
below max_downtime */

return 1;
}
}

return 0;
}

static void blk_mig_cleanup(Monitor *mon)
Expand Down Expand Up @@ -458,15 +517,15 @@ static int block_save_live(Monitor *mon, QEMUFile *f, int stage, void *opaque)

blk_mig_reset_dirty_cursor();

if(stage == 2) {
if (stage == 2) {
/* control the rate of transfer */
while ((block_mig_state.submitted +
block_mig_state.read_done) * BLOCK_SIZE <
qemu_file_get_rate_limit(f)) {
if (block_mig_state.bulk_completed == 0) {
/* first finish the bulk phase */
if (blk_mig_save_bulked_block(mon, f) == 0) {
/* finish saving bulk on all devices */
/* finished saving bulk on all devices */
block_mig_state.bulk_completed = 1;
}
} else {
Expand All @@ -486,9 +545,11 @@ static int block_save_live(Monitor *mon, QEMUFile *f, int stage, void *opaque)
}

if (stage == 3) {
/* we know for sure that save bulk is completed */
/* we know for sure that save bulk is completed and
all async read completed */
assert(block_mig_state.submitted == 0);

while(blk_mig_save_dirty_block(mon, f, 0) != 0);
while (blk_mig_save_dirty_block(mon, f, 0) != 0);
blk_mig_cleanup(mon);

/* report completion */
Expand Down

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