From 9ae90f73e623c8b8c7ec1fccd8ca493805df8fbd Mon Sep 17 00:00:00 2001 From: Hao Xiang Date: Mon, 11 Mar 2024 18:00:13 +0000 Subject: [PATCH] migration/multifd: Implement ram_save_target_page_multifd to handle multifd version of MigrationOps::ram_save_target_page. 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 Reviewed-by: Fabiano Rosas 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 --- migration/ram.c | 38 +++++++++++++++++++++++++++++--------- 1 file changed, 29 insertions(+), 9 deletions(-) diff --git a/migration/ram.c b/migration/ram.c index c26435adc7..8deb84984f 100644 --- a/migration/ram.c +++ b/migration/ram.c @@ -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();