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block/backup: make backup cluster size configurable 

64K might not always be appropriate, make this a runtime value.

Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Message-id: 1456433911-24718-2-git-send-email-jsnow@redhat.com
Signed-off-by: Jeff Cody <jcody@redhat.com>
This commit is contained in:
John Snow 2016-02-25 15:58:29 -05:00 committed by Jeff Cody
parent 21cd917ff5
commit 16096a4d47
1 changed files with 36 additions and 28 deletions
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64
block/backup.c
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@ -21,10 +21,7 @@
#include "qemu/ratelimit.h"
#include "sysemu/block-backend.h"
#define BACKUP_CLUSTER_BITS 16
#define BACKUP_CLUSTER_SIZE (1 << BACKUP_CLUSTER_BITS)
#define BACKUP_SECTORS_PER_CLUSTER (BACKUP_CLUSTER_SIZE / BDRV_SECTOR_SIZE)
#define BACKUP_CLUSTER_SIZE_DEFAULT (1 << 16)
#define SLICE_TIME 100000000ULL /* ns */
typedef struct CowRequest {
@ -46,9 +43,16 @@ typedef struct BackupBlockJob {
CoRwlock flush_rwlock;
uint64_t sectors_read;
HBitmap *bitmap;
int64_t cluster_size;
QLIST_HEAD(, CowRequest) inflight_reqs;
} BackupBlockJob;
/* Size of a cluster in sectors, instead of bytes. */
static inline int64_t cluster_size_sectors(BackupBlockJob *job)
{
return job->cluster_size / BDRV_SECTOR_SIZE;
}
/* See if in-flight requests overlap and wait for them to complete */
static void coroutine_fn wait_for_overlapping_requests(BackupBlockJob *job,
int64_t start,
@ -97,13 +101,14 @@ static int coroutine_fn backup_do_cow(BlockDriverState *bs,
QEMUIOVector bounce_qiov;
void *bounce_buffer = NULL;
int ret = 0;
int64_t sectors_per_cluster = cluster_size_sectors(job);
int64_t start, end;
int n;
qemu_co_rwlock_rdlock(&job->flush_rwlock);
start = sector_num / BACKUP_SECTORS_PER_CLUSTER;
end = DIV_ROUND_UP(sector_num + nb_sectors, BACKUP_SECTORS_PER_CLUSTER);
start = sector_num / sectors_per_cluster;
end = DIV_ROUND_UP(sector_num + nb_sectors, sectors_per_cluster);
trace_backup_do_cow_enter(job, start, sector_num, nb_sectors);
@ -118,12 +123,12 @@ static int coroutine_fn backup_do_cow(BlockDriverState *bs,
trace_backup_do_cow_process(job, start);
n = MIN(BACKUP_SECTORS_PER_CLUSTER,
n = MIN(sectors_per_cluster,
job->common.len / BDRV_SECTOR_SIZE -
start * BACKUP_SECTORS_PER_CLUSTER);
start * sectors_per_cluster);
if (!bounce_buffer) {
bounce_buffer = qemu_blockalign(bs, BACKUP_CLUSTER_SIZE);
bounce_buffer = qemu_blockalign(bs, job->cluster_size);
}
iov.iov_base = bounce_buffer;
iov.iov_len = n * BDRV_SECTOR_SIZE;
@ -131,10 +136,10 @@ static int coroutine_fn backup_do_cow(BlockDriverState *bs,
if (is_write_notifier) {
ret = bdrv_co_readv_no_serialising(bs,
start * BACKUP_SECTORS_PER_CLUSTER,
start * sectors_per_cluster,
n, &bounce_qiov);
} else {
ret = bdrv_co_readv(bs, start * BACKUP_SECTORS_PER_CLUSTER, n,
ret = bdrv_co_readv(bs, start * sectors_per_cluster, n,
&bounce_qiov);
}
if (ret < 0) {
@ -147,11 +152,11 @@ static int coroutine_fn backup_do_cow(BlockDriverState *bs,
if (buffer_is_zero(iov.iov_base, iov.iov_len)) {
ret = bdrv_co_write_zeroes(job->target,
start * BACKUP_SECTORS_PER_CLUSTER,
start * sectors_per_cluster,
n, BDRV_REQ_MAY_UNMAP);
} else {
ret = bdrv_co_writev(job->target,
start * BACKUP_SECTORS_PER_CLUSTER, n,
start * sectors_per_cluster, n,
&bounce_qiov);
}
if (ret < 0) {
@ -322,21 +327,22 @@ static int coroutine_fn backup_run_incremental(BackupBlockJob *job)
int64_t cluster;
int64_t end;
int64_t last_cluster = -1;
int64_t sectors_per_cluster = cluster_size_sectors(job);
BlockDriverState *bs = job->common.bs;
HBitmapIter hbi;
granularity = bdrv_dirty_bitmap_granularity(job->sync_bitmap);
clusters_per_iter = MAX((granularity / BACKUP_CLUSTER_SIZE), 1);
clusters_per_iter = MAX((granularity / job->cluster_size), 1);
bdrv_dirty_iter_init(job->sync_bitmap, &hbi);
/* Find the next dirty sector(s) */
while ((sector = hbitmap_iter_next(&hbi)) != -1) {
cluster = sector / BACKUP_SECTORS_PER_CLUSTER;
cluster = sector / sectors_per_cluster;
/* Fake progress updates for any clusters we skipped */
if (cluster != last_cluster + 1) {
job->common.offset += ((cluster - last_cluster - 1) *
BACKUP_CLUSTER_SIZE);
job->cluster_size);
}
for (end = cluster + clusters_per_iter; cluster < end; cluster++) {
@ -344,8 +350,8 @@ static int coroutine_fn backup_run_incremental(BackupBlockJob *job)
if (yield_and_check(job)) {
return ret;
}
ret = backup_do_cow(bs, cluster * BACKUP_SECTORS_PER_CLUSTER,
BACKUP_SECTORS_PER_CLUSTER, &error_is_read,
ret = backup_do_cow(bs, cluster * sectors_per_cluster,
sectors_per_cluster, &error_is_read,
false);
if ((ret < 0) &&
backup_error_action(job, error_is_read, -ret) ==
@ -357,17 +363,17 @@ static int coroutine_fn backup_run_incremental(BackupBlockJob *job)
/* If the bitmap granularity is smaller than the backup granularity,
* we need to advance the iterator pointer to the next cluster. */
if (granularity < BACKUP_CLUSTER_SIZE) {
bdrv_set_dirty_iter(&hbi, cluster * BACKUP_SECTORS_PER_CLUSTER);
if (granularity < job->cluster_size) {
bdrv_set_dirty_iter(&hbi, cluster * sectors_per_cluster);
}
last_cluster = cluster - 1;
}
/* Play some final catchup with the progress meter */
end = DIV_ROUND_UP(job->common.len, BACKUP_CLUSTER_SIZE);
end = DIV_ROUND_UP(job->common.len, job->cluster_size);
if (last_cluster + 1 < end) {
job->common.offset += ((end - last_cluster - 1) * BACKUP_CLUSTER_SIZE);
job->common.offset += ((end - last_cluster - 1) * job->cluster_size);
}
return ret;
@ -384,13 +390,14 @@ static void coroutine_fn backup_run(void *opaque)
.notify = backup_before_write_notify,
};
int64_t start, end;
int64_t sectors_per_cluster = cluster_size_sectors(job);
int ret = 0;
QLIST_INIT(&job->inflight_reqs);
qemu_co_rwlock_init(&job->flush_rwlock);
start = 0;
end = DIV_ROUND_UP(job->common.len, BACKUP_CLUSTER_SIZE);
end = DIV_ROUND_UP(job->common.len, job->cluster_size);
job->bitmap = hbitmap_alloc(end, 0);
@ -427,7 +434,7 @@ static void coroutine_fn backup_run(void *opaque)
/* Check to see if these blocks are already in the
* backing file. */
for (i = 0; i < BACKUP_SECTORS_PER_CLUSTER;) {
for (i = 0; i < sectors_per_cluster;) {
/* bdrv_is_allocated() only returns true/false based
* on the first set of sectors it comes across that
* are are all in the same state.
@ -436,8 +443,8 @@ static void coroutine_fn backup_run(void *opaque)
* needed but at some point that is always the case. */
alloced =
bdrv_is_allocated(bs,
start * BACKUP_SECTORS_PER_CLUSTER + i,
BACKUP_SECTORS_PER_CLUSTER - i, &n);
start * sectors_per_cluster + i,
sectors_per_cluster - i, &n);
i += n;
if (alloced == 1 || n == 0) {
@ -452,8 +459,8 @@ static void coroutine_fn backup_run(void *opaque)
}
}
/* FULL sync mode we copy the whole drive. */
ret = backup_do_cow(bs, start * BACKUP_SECTORS_PER_CLUSTER,
BACKUP_SECTORS_PER_CLUSTER, &error_is_read, false);
ret = backup_do_cow(bs, start * sectors_per_cluster,
sectors_per_cluster, &error_is_read, false);
if (ret < 0) {
/* Depending on error action, fail now or retry cluster */
BlockErrorAction action =
@ -571,6 +578,7 @@ void backup_start(BlockDriverState *bs, BlockDriverState *target,
job->sync_mode = sync_mode;
job->sync_bitmap = sync_mode == MIRROR_SYNC_MODE_INCREMENTAL ?
sync_bitmap : NULL;
job->cluster_size = BACKUP_CLUSTER_SIZE_DEFAULT;
job->common.len = len;
job->common.co = qemu_coroutine_create(backup_run);
block_job_txn_add_job(txn, &job->common);