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[PULL 10/17] migration/ram: Discard RAM when growing RAM blocks after ra
From: |
Dr. David Alan Gilbert (git) |
Subject: |
[PULL 10/17] migration/ram: Discard RAM when growing RAM blocks after ram_postcopy_incoming_init() |
Date: |
Thu, 13 May 2021 18:37:30 +0100 |
From: David Hildenbrand <david@redhat.com>
In case we grow our RAM after ram_postcopy_incoming_init() (e.g., when
synchronizing the RAM block state with the migration source), the resized
part would not get discarded. Let's perform that when being notified
about a resize while postcopy has been advised, but is not listening
yet. With precopy, the process is as following:
1. VM created
- RAM blocks are created
2. Incomming migration started
- Postcopy is advised
- All pages in RAM blocks are discarded
3. Precopy starts
- RAM blocks are resized to match the size on the migration source.
- RAM pages from precopy stream are loaded
- Uffd handler is registered, postcopy starts listening
4. Guest started, postcopy running
- Pagefaults get resolved, pages get placed
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
Message-Id: <20210429112708.12291-7-david@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
---
migration/ram.c | 30 ++++++++++++++++++++++++++++++
1 file changed, 30 insertions(+)
diff --git a/migration/ram.c b/migration/ram.c
index 77922c445e..e1d081d334 100644
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -4099,6 +4099,7 @@ static SaveVMHandlers savevm_ram_handlers = {
static void ram_mig_ram_block_resized(RAMBlockNotifier *n, void *host,
size_t old_size, size_t new_size)
{
+ PostcopyState ps = postcopy_state_get();
ram_addr_t offset;
RAMBlock *rb = qemu_ram_block_from_host(host, false, &offset);
Error *err = NULL;
@@ -4119,6 +4120,35 @@ static void ram_mig_ram_block_resized(RAMBlockNotifier
*n, void *host,
error_free(err);
migration_cancel();
}
+
+ switch (ps) {
+ case POSTCOPY_INCOMING_ADVISE:
+ /*
+ * Update what ram_postcopy_incoming_init()->init_range() does at the
+ * time postcopy was advised. Syncing RAM blocks with the source will
+ * result in RAM resizes.
+ */
+ if (old_size < new_size) {
+ if (ram_discard_range(rb->idstr, old_size, new_size - old_size)) {
+ error_report("RAM block '%s' discard of resized RAM failed",
+ rb->idstr);
+ }
+ }
+ break;
+ case POSTCOPY_INCOMING_NONE:
+ case POSTCOPY_INCOMING_RUNNING:
+ case POSTCOPY_INCOMING_END:
+ /*
+ * Once our guest is running, postcopy does no longer care about
+ * resizes. When growing, the new memory was not available on the
+ * source, no handler needed.
+ */
+ break;
+ default:
+ error_report("RAM block '%s' resized during postcopy state: %d",
+ rb->idstr, ps);
+ exit(-1);
+ }
}
static RAMBlockNotifier ram_mig_ram_notifier = {
--
2.31.1
- Re: [PULL 00/17] migration queue, (continued)
- [PULL 00/17] migration queue, Dr. David Alan Gilbert (git), 2021/05/13
- [PULL 01/17] migrate/ram: remove "ram_bulk_stage" and "fpo_enabled", Dr. David Alan Gilbert (git), 2021/05/13
- [PULL 02/17] migration/ram: Reduce unnecessary rate limiting, Dr. David Alan Gilbert (git), 2021/05/13
- [PULL 03/17] migration/ram: Optimize ram_save_host_page(), Dr. David Alan Gilbert (git), 2021/05/13
- [PULL 04/17] migration: Drop redundant query-migrate result @blocked, Dr. David Alan Gilbert (git), 2021/05/13
- [PULL 05/17] util: vfio-helpers: Factor out and fix processing of existing ram blocks, Dr. David Alan Gilbert (git), 2021/05/13
- [PULL 06/17] numa: Teach ram block notifiers about resizeable ram blocks, Dr. David Alan Gilbert (git), 2021/05/13
- [PULL 07/17] numa: Make all callbacks of ram block notifiers optional, Dr. David Alan Gilbert (git), 2021/05/13
- [PULL 08/17] migration/ram: Handle RAM block resizes during precopy, Dr. David Alan Gilbert (git), 2021/05/13
- [PULL 10/17] migration/ram: Discard RAM when growing RAM blocks after ram_postcopy_incoming_init(),
Dr. David Alan Gilbert (git) <=
- [PULL 09/17] exec: Relax range check in ram_block_discard_range(), Dr. David Alan Gilbert (git), 2021/05/13
- [PULL 11/17] migration/ram: Simplify host page handling in ram_load_postcopy(), Dr. David Alan Gilbert (git), 2021/05/13
- [PULL 13/17] migration/multifd: Print used_length of memory block, Dr. David Alan Gilbert (git), 2021/05/13
- [PULL 12/17] migration/ram: Handle RAM block resizes during postcopy, Dr. David Alan Gilbert (git), 2021/05/13
- [PULL 14/17] migration/ram: Use offset_in_ramblock() in range checks, Dr. David Alan Gilbert (git), 2021/05/13
- [PULL 15/17] tests/migration-test: Fix "true" vs true, Dr. David Alan Gilbert (git), 2021/05/13
- [PULL 16/17] tests/qtest/migration-test: Use g_autofree to avoid leaks on error paths, Dr. David Alan Gilbert (git), 2021/05/13
- [PULL 17/17] tests/migration: introduce multifd into guestperf, Dr. David Alan Gilbert (git), 2021/05/13
- Re: [PULL 00/17] migration queue, Peter Maydell, 2021/05/14