[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[Qemu-devel] [PATCH 17/22] block: Generalise and optimise COR serialisat
From: |
Kevin Wolf |
Subject: |
[Qemu-devel] [PATCH 17/22] block: Generalise and optimise COR serialisation |
Date: |
Wed, 11 Dec 2013 22:08:24 +0100 |
Change the API so that specific requests can be marked serialising. Only
these requests are checked for overlaps then.
This means that during a Copy on Read operation, not all requests
overlapping other requests are serialised any more, but only those that
actually overlap with the specific COR request.
Also remove COR from function and variable names because this
functionality can be useful in other contexts.
Signed-off-by: Kevin Wolf <address@hidden>
---
block.c | 40 +++++++++++++++++++++++++---------------
include/block/block_int.h | 5 +++--
2 files changed, 28 insertions(+), 17 deletions(-)
diff --git a/block.c b/block.c
index 6dddb7c..40be327 100644
--- a/block.c
+++ b/block.c
@@ -2028,6 +2028,10 @@ int bdrv_commit_all(void)
*/
static void tracked_request_end(BdrvTrackedRequest *req)
{
+ if (req->serialising) {
+ req->bs->serialising_in_flight--;
+ }
+
QLIST_REMOVE(req, list);
qemu_co_queue_restart_all(&req->wait_queue);
}
@@ -2046,6 +2050,7 @@ static void tracked_request_begin(BdrvTrackedRequest *req,
.bytes = bytes,
.is_write = is_write,
.co = qemu_coroutine_self(),
+ .serialising = false,
};
qemu_co_queue_init(&req->wait_queue);
@@ -2053,6 +2058,14 @@ static void tracked_request_begin(BdrvTrackedRequest
*req,
QLIST_INSERT_HEAD(&bs->tracked_requests, req, list);
}
+static void mark_request_serialising(BdrvTrackedRequest *req)
+{
+ if (!req->serialising) {
+ req->bs->serialising_in_flight++;
+ req->serialising = true;
+ }
+}
+
/**
* Round a region to cluster boundaries
*/
@@ -2105,26 +2118,31 @@ static bool tracked_request_overlaps(BdrvTrackedRequest
*req,
return true;
}
-static void coroutine_fn wait_for_overlapping_requests(BlockDriverState *bs,
- BdrvTrackedRequest *self, int64_t offset, unsigned int bytes)
+static void coroutine_fn wait_serialising_requests(BdrvTrackedRequest *self)
{
+ BlockDriverState *bs = self->bs;
BdrvTrackedRequest *req;
int64_t cluster_offset;
unsigned int cluster_bytes;
bool retry;
+ if (!bs->serialising_in_flight) {
+ return;
+ }
+
/* If we touch the same cluster it counts as an overlap. This guarantees
* that allocating writes will be serialized and not race with each other
* for the same cluster. For example, in copy-on-read it ensures that the
* CoR read and write operations are atomic and guest writes cannot
* interleave between them.
*/
- round_bytes_to_clusters(bs, offset, bytes, &cluster_offset,
&cluster_bytes);
+ round_bytes_to_clusters(bs, self->offset, self->bytes,
+ &cluster_offset, &cluster_bytes);
do {
retry = false;
QLIST_FOREACH(req, &bs->tracked_requests, list) {
- if (req == self) {
+ if (req == self || (!req->serialising && !self->serialising)) {
continue;
}
if (tracked_request_overlaps(req, cluster_offset, cluster_bytes)) {
@@ -2738,12 +2756,10 @@ static int coroutine_fn
bdrv_aligned_preadv(BlockDriverState *bs,
/* Handle Copy on Read and associated serialisation */
if (flags & BDRV_REQ_COPY_ON_READ) {
- bs->copy_on_read_in_flight++;
+ mark_request_serialising(req);
}
- if (bs->copy_on_read_in_flight) {
- wait_for_overlapping_requests(bs, req, offset, bytes);
- }
+ wait_serialising_requests(req);
if (flags & BDRV_REQ_COPY_ON_READ) {
int pnum;
@@ -2791,10 +2807,6 @@ static int coroutine_fn
bdrv_aligned_preadv(BlockDriverState *bs,
}
out:
- if (flags & BDRV_REQ_COPY_ON_READ) {
- bs->copy_on_read_in_flight--;
- }
-
return ret;
}
@@ -2992,9 +3004,7 @@ static int coroutine_fn
bdrv_aligned_pwritev(BlockDriverState *bs,
assert((offset & (BDRV_SECTOR_SIZE - 1)) == 0);
assert((bytes & (BDRV_SECTOR_SIZE - 1)) == 0);
- if (bs->copy_on_read_in_flight) {
- wait_for_overlapping_requests(bs, req, offset, bytes);
- }
+ wait_serialising_requests(req);
ret = notifier_with_return_list_notify(&bs->before_write_notifiers, req);
diff --git a/include/block/block_int.h b/include/block/block_int.h
index a11e5c9..b00402b 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -60,6 +60,7 @@ typedef struct BdrvTrackedRequest {
int64_t offset;
unsigned int bytes;
bool is_write;
+ bool serialising;
QLIST_ENTRY(BdrvTrackedRequest) list;
Coroutine *co; /* owner, used for deadlock detection */
CoQueue wait_queue; /* coroutines blocked on this request */
@@ -296,8 +297,8 @@ struct BlockDriverState {
/* Callback before write request is processed */
NotifierWithReturnList before_write_notifiers;
- /* number of in-flight copy-on-read requests */
- unsigned int copy_on_read_in_flight;
+ /* number of in-flight serialising requests */
+ unsigned int serialising_in_flight;
/* I/O throttling */
ThrottleState throttle_state;
--
1.8.1.4
- [Qemu-devel] [PATCH 09/22] block: Introduce bdrv_aligned_preadv(), (continued)
- [Qemu-devel] [PATCH 09/22] block: Introduce bdrv_aligned_preadv(), Kevin Wolf, 2013/12/11
- [Qemu-devel] [PATCH 07/22] block: rename buffer_alignment to guest_block_size, Kevin Wolf, 2013/12/11
- [Qemu-devel] [PATCH 10/22] block: Introduce bdrv_co_do_preadv(), Kevin Wolf, 2013/12/11
- [Qemu-devel] [PATCH 11/22] block: Introduce bdrv_aligned_pwritev(), Kevin Wolf, 2013/12/11
- [Qemu-devel] [PATCH 12/22] block: write: Handle COR dependency after I/O throttling, Kevin Wolf, 2013/12/11
- [Qemu-devel] [PATCH 13/22] block: Introduce bdrv_co_do_pwritev(), Kevin Wolf, 2013/12/11
- [Qemu-devel] [PATCH 14/22] block: Switch BdrvTrackedRequest to byte granularity, Kevin Wolf, 2013/12/11
- [Qemu-devel] [PATCH 16/22] block: Make zero-after-EOF work with larger alignment, Kevin Wolf, 2013/12/11
- [Qemu-devel] [PATCH 15/22] block: Allow waiting for overlapping requests between begin/end, Kevin Wolf, 2013/12/11
- [Qemu-devel] [PATCH 17/22] block: Generalise and optimise COR serialisation,
Kevin Wolf <=
- [Qemu-devel] [PATCH 18/22] block: Make overlap range for serialisation dynamic, Kevin Wolf, 2013/12/11
- [Qemu-devel] [PATCH 19/22] block: Align requests in bdrv_co_do_pwritev(), Kevin Wolf, 2013/12/11
- [Qemu-devel] [PATCH 20/22] block: Change coroutine wrapper to byte granularity, Kevin Wolf, 2013/12/11
- [Qemu-devel] [PATCH 21/22] block: Make bdrv_pread() a bdrv_prwv_co() wrapper, Kevin Wolf, 2013/12/11
- [Qemu-devel] [PATCH 22/22] block: Make bdrv_pwrite() a bdrv_prwv_co() wrapper, Kevin Wolf, 2013/12/11
- Re: [Qemu-devel] [PATCH 00/22] block: Support for 512b-on-4k emulation, Peter Lieven, 2013/12/12