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migration: simplify check to use qemu file buffer

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Firstly, renaming the old matching_page_sizes variable to
matches_target_page_size, which suites more to what it did (it only
checks against target page size rather than multiple page sizes).
Meanwhile, simplify the check logic a bit, and enhance the comments.
Should have no functional change.

Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Message-Id: <20180710091902.28780-2-peterx@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
This commit is contained in:
Peter Xu 2018-07-10 17:18:53 +08:00 committed by Dr. David Alan Gilbert
parent a429e7f488
commit 1aa8367861
1 changed files with 11 additions and 6 deletions
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17
migration/ram.c
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@ -3580,7 +3580,7 @@ static int ram_load_postcopy(QEMUFile *f)
{ {
int flags = 0, ret = 0; int flags = 0, ret = 0;
bool place_needed = false; bool place_needed = false;
bool matching_page_sizes = false; bool matches_target_page_size = false;
MigrationIncomingState *mis = migration_incoming_get_current(); MigrationIncomingState *mis = migration_incoming_get_current();
/* Temporary page that is later 'placed' */ /* Temporary page that is later 'placed' */
void *postcopy_host_page = postcopy_get_tmp_page(mis); void *postcopy_host_page = postcopy_get_tmp_page(mis);
@ -3620,7 +3620,7 @@ static int ram_load_postcopy(QEMUFile *f)
ret = -EINVAL; ret = -EINVAL;
break; break;
} }
matching_page_sizes = block->page_size == TARGET_PAGE_SIZE; matches_target_page_size = block->page_size == TARGET_PAGE_SIZE;
/* /*
* Postcopy requires that we place whole host pages atomically; * Postcopy requires that we place whole host pages atomically;
* these may be huge pages for RAMBlocks that are backed by * these may be huge pages for RAMBlocks that are backed by
@ -3668,12 +3668,17 @@ static int ram_load_postcopy(QEMUFile *f)
case RAM_SAVE_FLAG_PAGE: case RAM_SAVE_FLAG_PAGE:
all_zero = false; all_zero = false;
if (!place_needed || !matching_page_sizes) { if (!matches_target_page_size) {
/* For huge pages, we always use temporary buffer */
qemu_get_buffer(f, page_buffer, TARGET_PAGE_SIZE); qemu_get_buffer(f, page_buffer, TARGET_PAGE_SIZE);
} else { } else {
/* Avoids the qemu_file copy during postcopy, which is /*
* going to do a copy later; can only do it when we * For small pages that matches target page size, we
* do this read in one go (matching page sizes) * avoid the qemu_file copy. Instead we directly use
* the buffer of QEMUFile to place the page. Note: we
* cannot do any QEMUFile operation before using that
* buffer to make sure the buffer is valid when
* placing the page.
*/ */
qemu_get_buffer_in_place(f, (uint8_t **)&place_source, qemu_get_buffer_in_place(f, (uint8_t **)&place_source,
TARGET_PAGE_SIZE); TARGET_PAGE_SIZE);