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migration/multifd: Implement ram_save_target_page_multifd to handle multifd version of MigrationOps::ram_save_target_page.

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1. Add a dedicated handler for MigrationOps::ram_save_target_page in
multifd live migration.
2. Refactor ram_save_target_page_legacy so that the legacy and multifd
handlers don't have internal functions calling into each other.

Signed-off-by: Hao Xiang <hao.xiang@bytedance.com>
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Message-Id: <20240226195654.934709-4-hao.xiang@bytedance.com>
Link: https://lore.kernel.org/r/20240311180015.3359271-6-hao.xiang@linux.dev
Signed-off-by: Peter Xu <peterx@redhat.com>
This commit is contained in:
Hao Xiang 2024-03-11 18:00:13 +00:00 committed by Peter Xu
parent 303e6f54f9
commit 9ae90f73e6
1 changed files with 29 additions and 9 deletions
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38
migration/ram.c
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@ -2079,7 +2079,6 @@ static bool save_compress_page(RAMState *rs, PageSearchStatus *pss,
*/
static int ram_save_target_page_legacy(RAMState *rs, PageSearchStatus *pss)
{
RAMBlock *block = pss->block;
ram_addr_t offset = ((ram_addr_t)pss->page) << TARGET_PAGE_BITS;
int res;
@ -2095,17 +2094,33 @@ static int ram_save_target_page_legacy(RAMState *rs, PageSearchStatus *pss)
return 1;
}
return ram_save_page(rs, pss);
}
/**
* ram_save_target_page_multifd: send one target page to multifd workers
*
* Returns 1 if the page was queued, -1 otherwise.
*
* @rs: current RAM state
* @pss: data about the page we want to send
*/
static int ram_save_target_page_multifd(RAMState *rs, PageSearchStatus *pss)
{
RAMBlock *block = pss->block;
ram_addr_t offset = ((ram_addr_t)pss->page) << TARGET_PAGE_BITS;
/*
* Do not use multifd in postcopy as one whole host page should be
* placed. Meanwhile postcopy requires atomic update of pages, so even
* if host page size == guest page size the dest guest during run may
* still see partially copied pages which is data corruption.
* While using multifd live migration, we still need to handle zero
* page checking on the migration main thread.
*/
if (migrate_multifd() && !migration_in_postcopy()) {
return ram_save_multifd_page(block, offset);
if (migrate_zero_page_detection() == ZERO_PAGE_DETECTION_LEGACY) {
if (save_zero_page(rs, pss, offset)) {
return 1;
}
}
return ram_save_page(rs, pss);
return ram_save_multifd_page(block, offset);
}
/* Should be called before sending a host page */
@ -3112,7 +3127,12 @@ static int ram_save_setup(QEMUFile *f, void *opaque)
}
migration_ops = g_malloc0(sizeof(MigrationOps));
migration_ops->ram_save_target_page = ram_save_target_page_legacy;
if (migrate_multifd()) {
migration_ops->ram_save_target_page = ram_save_target_page_multifd;
} else {
migration_ops->ram_save_target_page = ram_save_target_page_legacy;
}
bql_unlock();
ret = multifd_send_sync_main();