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[PULL 07/25] migration: remove unreachble RDMA code in save_hook impl
From: |
Juan Quintela |
Subject: |
[PULL 07/25] migration: remove unreachble RDMA code in save_hook impl |
Date: |
Wed, 22 Jun 2022 02:25:29 +0200 |
From: Daniel P. Berrangé <berrange@redhat.com>
The QEMUFile 'save_hook' callback has a 'size_t size' parameter.
The RDMA impl of this has logic that takes different actions
depending on whether the value is zero or non-zero. It has
commented out logic that would have taken further actions
if the value was negative.
The only place where the 'save_hook' callback is invoked is
the ram_control_save_page() method, which passes 'size'
through from its caller. The only caller of this method is
in turn control_save_page(). This method unconditionally
passes the 'TARGET_PAGE_SIZE' constant for the 'size' parameter.
IOW, the only scenario for 'size' that can execute in the
qemu_rdma_save_page method is 'size > 0'. The remaining code
has been unreachable since RDMA support was first introduced
9 years ago.
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
---
migration/rdma.c | 120 +++++++++--------------------------------------
1 file changed, 21 insertions(+), 99 deletions(-)
diff --git a/migration/rdma.c b/migration/rdma.c
index 8504152f39..c5fa4a408a 100644
--- a/migration/rdma.c
+++ b/migration/rdma.c
@@ -1462,34 +1462,6 @@ static uint64_t qemu_rdma_make_wrid(uint64_t wr_id,
uint64_t index,
return result;
}
-/*
- * Set bit for unregistration in the next iteration.
- * We cannot transmit right here, but will unpin later.
- */
-static void qemu_rdma_signal_unregister(RDMAContext *rdma, uint64_t index,
- uint64_t chunk, uint64_t wr_id)
-{
- if (rdma->unregistrations[rdma->unregister_next] != 0) {
- error_report("rdma migration: queue is full");
- } else {
- RDMALocalBlock *block = &(rdma->local_ram_blocks.block[index]);
-
- if (!test_and_set_bit(chunk, block->unregister_bitmap)) {
- trace_qemu_rdma_signal_unregister_append(chunk,
- rdma->unregister_next);
-
- rdma->unregistrations[rdma->unregister_next++] =
- qemu_rdma_make_wrid(wr_id, index, chunk);
-
- if (rdma->unregister_next == RDMA_SIGNALED_SEND_MAX) {
- rdma->unregister_next = 0;
- }
- } else {
- trace_qemu_rdma_signal_unregister_already(chunk);
- }
- }
-}
-
/*
* Consult the connection manager to see a work request
* (of any kind) has completed.
@@ -3237,23 +3209,7 @@ qio_channel_rdma_shutdown(QIOChannel *ioc,
* Offset is an offset to be added to block_offset and used
* to also lookup the corresponding RAMBlock.
*
- * @size > 0 :
- * Initiate an transfer this size.
- *
- * @size == 0 :
- * A 'hint' or 'advice' that means that we wish to speculatively
- * and asynchronously unregister this memory. In this case, there is no
- * guarantee that the unregister will actually happen, for example,
- * if the memory is being actively transmitted. Additionally, the memory
- * may be re-registered at any future time if a write within the same
- * chunk was requested again, even if you attempted to unregister it
- * here.
- *
- * @size < 0 : TODO, not yet supported
- * Unregister the memory NOW. This means that the caller does not
- * expect there to be any future RDMA transfers and we just want to
clean
- * things up. This is used in case the upper layer owns the memory and
- * cannot wait for qemu_fclose() to occur.
+ * @size : Number of bytes to transfer
*
* @bytes_sent : User-specificed pointer to indicate how many bytes were
* sent. Usually, this will not be more than a few bytes of
@@ -3282,61 +3238,27 @@ static size_t qemu_rdma_save_page(QEMUFile *f, void
*opaque,
qemu_fflush(f);
- if (size > 0) {
- /*
- * Add this page to the current 'chunk'. If the chunk
- * is full, or the page doesn't belong to the current chunk,
- * an actual RDMA write will occur and a new chunk will be formed.
- */
- ret = qemu_rdma_write(f, rdma, block_offset, offset, size);
- if (ret < 0) {
- error_report("rdma migration: write error! %d", ret);
- goto err;
- }
+ /*
+ * Add this page to the current 'chunk'. If the chunk
+ * is full, or the page doesn't belong to the current chunk,
+ * an actual RDMA write will occur and a new chunk will be formed.
+ */
+ ret = qemu_rdma_write(f, rdma, block_offset, offset, size);
+ if (ret < 0) {
+ error_report("rdma migration: write error! %d", ret);
+ goto err;
+ }
- /*
- * We always return 1 bytes because the RDMA
- * protocol is completely asynchronous. We do not yet know
- * whether an identified chunk is zero or not because we're
- * waiting for other pages to potentially be merged with
- * the current chunk. So, we have to call qemu_update_position()
- * later on when the actual write occurs.
- */
- if (bytes_sent) {
- *bytes_sent = 1;
- }
- } else {
- uint64_t index, chunk;
-
- /* TODO: Change QEMUFileOps prototype to be signed: size_t => long
- if (size < 0) {
- ret = qemu_rdma_drain_cq(f, rdma);
- if (ret < 0) {
- fprintf(stderr, "rdma: failed to synchronously drain"
- " completion queue before unregistration.\n");
- goto err;
- }
- }
- */
-
- ret = qemu_rdma_search_ram_block(rdma, block_offset,
- offset, size, &index, &chunk);
-
- if (ret) {
- error_report("ram block search failed");
- goto err;
- }
-
- qemu_rdma_signal_unregister(rdma, index, chunk, 0);
-
- /*
- * TODO: Synchronous, guaranteed unregistration (should not occur
during
- * fast-path). Otherwise, unregisters will process on the next call to
- * qemu_rdma_drain_cq()
- if (size < 0) {
- qemu_rdma_unregister_waiting(rdma);
- }
- */
+ /*
+ * We always return 1 bytes because the RDMA
+ * protocol is completely asynchronous. We do not yet know
+ * whether an identified chunk is zero or not because we're
+ * waiting for other pages to potentially be merged with
+ * the current chunk. So, we have to call qemu_update_position()
+ * later on when the actual write occurs.
+ */
+ if (bytes_sent) {
+ *bytes_sent = 1;
}
/*
--
2.35.3
- [PULL 00/25] Migration 20220621 patches, Juan Quintela, 2022/06/21
- [PULL 01/25] migration: Remove RDMA_UNREGISTRATION_EXAMPLE, Juan Quintela, 2022/06/21
- [PULL 02/25] QIOChannelSocket: Introduce assert and reduce ifdefs to improve readability, Juan Quintela, 2022/06/21
- [PULL 03/25] QIOChannelSocket: Fix zero-copy send so socket flush works, Juan Quintela, 2022/06/21
- [PULL 04/25] migration: Change zero_copy_send from migration parameter to migration capability, Juan Quintela, 2022/06/21
- [PULL 05/25] io: add a QIOChannelNull equivalent to /dev/null, Juan Quintela, 2022/06/21
- [PULL 08/25] migration: rename rate limiting fields in QEMUFile, Juan Quintela, 2022/06/21
- [PULL 06/25] migration: switch to use QIOChannelNull for dummy channel, Juan Quintela, 2022/06/21
- [PULL 09/25] migration: rename 'pos' field in QEMUFile to 'bytes_processed', Juan Quintela, 2022/06/21
- [PULL 07/25] migration: remove unreachble RDMA code in save_hook impl,
Juan Quintela <=
- [PULL 12/25] migration: rename qemu_file_update_transfer to qemu_file_acct_rate_limit, Juan Quintela, 2022/06/21
- [PULL 10/25] migration: rename qemu_ftell to qemu_file_total_transferred, Juan Quintela, 2022/06/21
- [PULL 11/25] migration: rename qemu_update_position to qemu_file_credit_transfer, Juan Quintela, 2022/06/21
- [PULL 13/25] migration: introduce a QIOChannel impl for BlockDriverState VMState, Juan Quintela, 2022/06/21
- [PULL 14/25] migration: convert savevm to use QIOChannelBlock for VMState, Juan Quintela, 2022/06/21
- [PULL 15/25] migration: stop passing 'opaque' parameter to QEMUFile hooks, Juan Quintela, 2022/06/21
- [PULL 18/25] migration: remove unused QEMUFileGetFD typedef / qemu_get_fd method, Juan Quintela, 2022/06/21
- [PULL 16/25] migration: hardcode assumption that QEMUFile is backed with QIOChannel, Juan Quintela, 2022/06/21
- [PULL 17/25] migration: introduce new constructors for QEMUFile, Juan Quintela, 2022/06/21
- [PULL 20/25] migration: remove the QEMUFileOps 'set_blocking' callback, Juan Quintela, 2022/06/21