[Top][All Lists]
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[Qemu-devel] [PATCH 46/47] mirror: support more than one in-flight AIO o
From: |
Paolo Bonzini |
Subject: |
[Qemu-devel] [PATCH 46/47] mirror: support more than one in-flight AIO operation |
Date: |
Tue, 24 Jul 2012 13:04:24 +0200 |
With AIO support in place, we can start copying more than one chunk
in parallel. This patch introduces the required infrastructure for
this: the buffer is split into multiple granularity-sized chunks,
and there is a free list to access them.
Because of copy-on-write, a single operation may already require
multiple chunks to be available on the free list. The next patch
will make this more general, but the logic remains the same overall.
In addition, two different iterations on the HBitmap may want to
copy the same cluster. We avoid this by keeping a bitmap of in-flight
I/O operations, and blocking until the previous iteration completes.
This should be a relatively rare occurrence, though, and as long as
there is no overlap the next iteration can start before the previous
one finishes.
Signed-off-by: Paolo Bonzini <address@hidden>
---
block/mirror.c | 107 ++++++++++++++++++++++++++++++++++++++++++++++++++------
trace-events | 4 ++-
2 files changed, 99 insertions(+), 12 deletions(-)
diff --git a/block/mirror.c b/block/mirror.c
index 475a7e0..93e718f 100644
--- a/block/mirror.c
+++ b/block/mirror.c
@@ -18,6 +18,14 @@
#include "bitmap.h"
#define SLICE_TIME 100000000ULL /* ns */
+#define MAX_IN_FLIGHT 16
+
+/* The mirroring buffer is a list of granularity-sized chunks.
+ * Free chunks are organized in a list.
+ */
+typedef struct MirrorBuffer {
+ QSIMPLEQ_ENTRY(MirrorBuffer) next;
+} MirrorBuffer;
typedef struct MirrorBlockJob {
BlockJob common;
@@ -33,7 +41,10 @@ typedef struct MirrorBlockJob {
unsigned long *cow_bitmap;
HBitmapIter hbi;
uint8_t *buf;
+ QSIMPLEQ_HEAD(, MirrorBuffer) buf_free;
+ int buf_free_count;
+ unsigned long *in_flight_bitmap;
int in_flight;
int ret;
} MirrorBlockJob;
@@ -41,7 +52,6 @@ typedef struct MirrorBlockJob {
typedef struct MirrorOp {
MirrorBlockJob *s;
QEMUIOVector qiov;
- struct iovec iov;
int64_t sector_num;
int nb_sectors;
} MirrorOp;
@@ -49,8 +59,22 @@ typedef struct MirrorOp {
static void mirror_iteration_done(MirrorOp *op)
{
MirrorBlockJob *s = op->s;
+ struct iovec *iov;
+ int64_t cluster_num;
+ int i, nb_chunks;
s->in_flight--;
+ iov = op->qiov.iov;
+ for (i = 0; i < op->qiov.niov; i++) {
+ MirrorBuffer *buf = (MirrorBuffer *) iov[i].iov_base;
+ QSIMPLEQ_INSERT_TAIL(&s->buf_free, buf, next);
+ s->buf_free_count++;
+ }
+
+ cluster_num = op->sector_num / s->granularity;
+ nb_chunks = op->nb_sectors / s->granularity;
+ bitmap_clear(s->in_flight_bitmap, cluster_num, nb_chunks);
+
trace_mirror_iteration_done(s, op->sector_num, op->nb_sectors);
g_slice_free(MirrorOp, op);
qemu_coroutine_enter(s->common.co, NULL);
@@ -102,8 +126,8 @@ static void mirror_read_complete(void *opaque, int ret)
static void coroutine_fn mirror_iteration(MirrorBlockJob *s)
{
BlockDriverState *source = s->common.bs;
- int nb_sectors, nb_sectors_chunk;
- int64_t end, sector_num, cluster_num;
+ int nb_sectors, nb_sectors_chunk, nb_chunks;
+ int64_t end, sector_num, cluster_num, next_sector, hbitmap_next_sector;
MirrorOp *op;
s->sector_num = hbitmap_iter_next(&s->hbi);
@@ -114,6 +138,8 @@ static void coroutine_fn mirror_iteration(MirrorBlockJob *s)
assert(s->sector_num >= 0);
}
+ hbitmap_next_sector = s->sector_num;
+
/* If we have no backing file yet in the destination, and the cluster size
* is very large, we need to do COW ourselves. The first time a cluster is
* copied, copy it entirely.
@@ -129,21 +155,58 @@ static void coroutine_fn mirror_iteration(MirrorBlockJob
*s)
bdrv_round_to_clusters(s->target,
sector_num, nb_sectors_chunk,
§or_num, &nb_sectors);
- bitmap_set(s->cow_bitmap, sector_num / nb_sectors_chunk,
- nb_sectors / nb_sectors_chunk);
+
+ /* The rounding may make us copy sectors before the
+ * first dirty one.
+ */
+ cluster_num = sector_num / nb_sectors_chunk;
+ }
+
+ /* Wait for I/O to this cluster (from a previous iteration) to be done. */
+ while (test_bit(cluster_num, s->in_flight_bitmap)) {
+ trace_mirror_yield_in_flight(s, sector_num, s->in_flight);
+ qemu_coroutine_yield();
}
end = s->common.len >> BDRV_SECTOR_BITS;
nb_sectors = MIN(nb_sectors, end - sector_num);
+ nb_chunks = (nb_sectors + nb_sectors_chunk - 1) / nb_sectors_chunk;
+ while (s->buf_free_count < nb_chunks) {
+ trace_mirror_yield_buf_busy(s, nb_chunks, s->in_flight);
+ qemu_coroutine_yield();
+ }
+
+ /* We have enough free space to copy these sectors. */
+ if (s->cow_bitmap) {
+ bitmap_set(s->cow_bitmap, cluster_num, nb_chunks);
+ }
/* Allocate a MirrorOp that is used as an AIO callback. */
op = g_slice_new(MirrorOp);
op->s = s;
- op->iov.iov_base = s->buf;
- op->iov.iov_len = nb_sectors * 512;
op->sector_num = sector_num;
op->nb_sectors = nb_sectors;
- qemu_iovec_init_external(&op->qiov, &op->iov, 1);
+
+ /* Now make a QEMUIOVector taking enough granularity-sized chunks
+ * from s->buf_free.
+ */
+ qemu_iovec_init(&op->qiov, nb_chunks);
+ next_sector = sector_num;
+ while (nb_chunks-- > 0) {
+ MirrorBuffer *buf = QSIMPLEQ_FIRST(&s->buf_free);
+ QSIMPLEQ_REMOVE_HEAD(&s->buf_free, next);
+ s->buf_free_count--;
+ qemu_iovec_add(&op->qiov, buf, s->granularity);
+
+ /* Advance the HBitmapIter in parallel, so that we do not examine
+ * the same sector twice.
+ */
+ if (next_sector > hbitmap_next_sector && bdrv_get_dirty(source,
next_sector)) {
+ hbitmap_next_sector = hbitmap_iter_next(&s->hbi);
+ }
+
+ next_sector += nb_sectors_chunk;
+ }
bdrv_reset_dirty(source, sector_num, nb_sectors);
@@ -154,6 +217,23 @@ static void coroutine_fn mirror_iteration(MirrorBlockJob
*s)
mirror_read_complete, op);
}
+static void mirror_free_init(MirrorBlockJob *s)
+{
+ int granularity = s->granularity;
+ size_t buf_size = s->buf_size;
+ uint8_t *buf = s->buf;
+
+ assert(s->buf_free_count == 0);
+ QSIMPLEQ_INIT(&s->buf_free);
+ while (buf_size != 0) {
+ MirrorBuffer *cur = (MirrorBuffer *)buf;
+ QSIMPLEQ_INSERT_TAIL(&s->buf_free, cur, next);
+ s->buf_free_count++;
+ buf_size -= granularity;
+ buf += granularity;
+ }
+}
+
static void mirror_drain(MirrorBlockJob *s)
{
while (s->in_flight > 0) {
@@ -182,6 +262,9 @@ static void coroutine_fn mirror_run(void *opaque)
return;
}
+ length = (bdrv_getlength(bs) + s->granularity - 1) / s->granularity;
+ s->in_flight_bitmap = bitmap_new(length);
+
/* If we have no backing file yet in the destination, we cannot let
* the destination do COW. Instead, we copy sectors around the
* dirty data if needed. We need a bitmap to do that.
@@ -192,7 +275,6 @@ static void coroutine_fn mirror_run(void *opaque)
bdrv_get_info(s->target, &bdi);
if (s->buf_size < bdi.cluster_size) {
s->buf_size = bdi.cluster_size;
- length = (bdrv_getlength(bs) + s->granularity - 1) /
s->granularity;
s->cow_bitmap = bitmap_new(length);
}
}
@@ -200,6 +282,7 @@ static void coroutine_fn mirror_run(void *opaque)
end = s->common.len >> BDRV_SECTOR_BITS;
s->buf = qemu_blockalign(bs, s->buf_size);
nb_sectors_chunk = s->granularity >> BDRV_SECTOR_BITS;
+ mirror_free_init(s);
if (s->mode == MIRROR_SYNC_MODE_FULL || s->mode == MIRROR_SYNC_MODE_TOP) {
/* First part, loop on the sectors and initialize the dirty bitmap. */
@@ -246,8 +329,9 @@ static void coroutine_fn mirror_run(void *opaque)
*/
if (qemu_get_clock_ns(rt_clock) - last_pause_ns < SLICE_TIME &&
s->common.iostatus == BLOCK_DEVICE_IO_STATUS_OK) {
- if (s->in_flight > 0) {
- trace_mirror_yield(s, s->in_flight, cnt);
+ if (s->in_flight == MAX_IN_FLIGHT || s->buf_free_count == 0 ||
+ (cnt == 0 && s->in_flight > 0)) {
+ trace_mirror_yield(s, s->in_flight, s->buf_free_count, cnt);
qemu_coroutine_yield();
continue;
} else if (cnt != 0) {
@@ -332,6 +416,7 @@ immediate_exit:
assert(s->in_flight == 0);
g_free(s->buf);
g_free(s->cow_bitmap);
+ g_free(s->in_flight_bitmap);
bdrv_set_dirty_tracking(bs, 0);
bdrv_iostatus_disable(s->target);
if (s->complete && ret == 0) {
diff --git a/trace-events b/trace-events
index fe20bd7..7ae11e9 100644
--- a/trace-events
+++ b/trace-events
@@ -84,7 +84,9 @@ mirror_before_sleep(void *s, int64_t cnt, int synced) "s %p
dirty count %"PRId64
mirror_one_iteration(void *s, int64_t sector_num, int nb_sectors) "s %p
sector_num %"PRId64" nb_sectors %d"
mirror_cow(void *s, int64_t sector_num) "s %p sector_num %"PRId64
mirror_iteration_done(void *s, int64_t sector_num, int nb_sectors) "s %p
sector_num %"PRId64" nb_sectors %d"
-mirror_yield(void *s, int64_t cnt, int in_flight) "s %p dirty count %"PRId64"
in_flight %d"
+mirror_yield(void *s, int64_t cnt, int buf_free_count, int in_flight) "s %p
dirty count %"PRId64" free buffers %d in_flight %d"
+mirror_yield_in_flight(void *s, int64_t sector_num, int in_flight) "s %p
sector_num %"PRId64" in_flight %d"
+mirror_yield_buf_busy(void *s, int nb_chunks, int in_flight) "s %p requested
chunks %d in_flight %d"
# blockdev.c
qmp_block_job_cancel(void *job) "job %p"
--
1.7.10.4
- Re: [Qemu-devel] [PATCH 31/47] qemu-iotests: add mirroring test case, (continued)
- [Qemu-devel] [PATCH 33/47] mirror: add support for on-source-error/on-target-error, Paolo Bonzini, 2012/07/24
- [Qemu-devel] [PATCH 32/47] block: forward bdrv_iostatus_reset to block job, Paolo Bonzini, 2012/07/24
- [Qemu-devel] [PATCH 34/47] qmp: add pull_event function, Paolo Bonzini, 2012/07/24
- [Qemu-devel] [PATCH 37/47] add hierarchical bitmap data type and test cases, Paolo Bonzini, 2012/07/24
- [Qemu-devel] [PATCH 39/47] block: make round_to_clusters public, Paolo Bonzini, 2012/07/24
- [Qemu-devel] [PATCH 40/47] mirror: perform COW if the cluster size is bigger than the granularity, Paolo Bonzini, 2012/07/24
- [Qemu-devel] [PATCH 46/47] mirror: support more than one in-flight AIO operation,
Paolo Bonzini <=
- [Qemu-devel] [PATCH 47/47] mirror: support arbitrarily-sized iterations, Paolo Bonzini, 2012/07/24
- [Qemu-devel] [PATCH 41/47] block: return count of dirty sectors, not chunks, Paolo Bonzini, 2012/07/24
- [Qemu-devel] [PATCH 36/47] host-utils: add ffsl and flsl, Paolo Bonzini, 2012/07/24
- [Qemu-devel] [PATCH 23/47] block: add target info to QMP query-blockjobs command, Paolo Bonzini, 2012/07/24
- [Qemu-devel] [PATCH 42/47] block: allow customizing the granularity of the dirty bitmap, Paolo Bonzini, 2012/07/24
- [Qemu-devel] [PATCH 17/47] qemu-iotests: add tests for streaming error handling, Paolo Bonzini, 2012/07/24
- [Qemu-devel] [PATCH 18/47] block: live snapshot documentation tweaks, Paolo Bonzini, 2012/07/24
- [Qemu-devel] [PATCH 22/47] block: make device optional in BlockInfo, Paolo Bonzini, 2012/07/24