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Mon, 27 Nov 2023 20:26:36 +0000 (UTC) Received: from dovecot-director2.suse.de ([10.150.64.162]) by imap1.dmz-prg2.suse.org with ESMTPSA id uDW3Cnz7ZGVfIQAAD6G6ig (envelope-from ); Mon, 27 Nov 2023 20:26:36 +0000 From: Fabiano Rosas To: qemu-devel@nongnu.org Cc: berrange@redhat.com, armbru@redhat.com, Juan Quintela , Peter Xu , Leonardo Bras , Claudio Fontana , Nikolay Borisov , Paolo Bonzini , David Hildenbrand , =?utf-8?q?Philippe_Mathieu-Daud=C3=A9?= Subject: [RFC PATCH v3 08/30] migration/ram: Add outgoing 'fixed-ram' migration Date: Mon, 27 Nov 2023 17:25:50 -0300 Message-Id: <20231127202612.23012-9-farosas@suse.de> X-Mailer: git-send-email 2.35.3 In-Reply-To: <20231127202612.23012-1-farosas@suse.de> References: <20231127202612.23012-1-farosas@suse.de> MIME-Version: 1.0 Authentication-Results: smtp-out1.suse.de; none X-Spam-Score: 0.90 X-Spamd-Result: default: False [0.90 / 50.00]; ARC_NA(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; FROM_HAS_DN(0.00)[]; TO_DN_SOME(0.00)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; R_MISSING_CHARSET(2.50)[]; MIME_GOOD(-0.10)[text/plain]; BROKEN_CONTENT_TYPE(1.50)[]; NEURAL_HAM_LONG(-1.00)[-1.000]; RCVD_COUNT_THREE(0.00)[3]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; RCPT_COUNT_SEVEN(0.00)[11]; MID_CONTAINS_FROM(1.00)[]; DBL_BLOCKED_OPENRESOLVER(0.00)[suse.de:email,suse.com:email]; FUZZY_BLOCKED(0.00)[rspamd.com]; FROM_EQ_ENVFROM(0.00)[]; MIME_TRACE(0.00)[0:+]; RCVD_TLS_ALL(0.00)[]; BAYES_HAM(-3.00)[100.00%] Received-SPF: pass client-ip=2a07:de40:b251:101:10:150:64:1; envelope-from=farosas@suse.de; helo=smtp-out1.suse.de X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org From: Nikolay Borisov Implement the outgoing migration side for the 'fixed-ram' capability. A bitmap is introduced to track which pages have been written in the migration file. Pages are written at a fixed location for every ramblock. Zero pages are ignored as they'd be zero in the destination migration as well. The migration stream is altered to put the dirty pages for a ramblock after its header instead of having a sequential stream of pages that follow the ramblock headers. Since all pages have a fixed location, RAM_SAVE_FLAG_EOS is no longer generated on every migration iteration. Without fixed-ram (current): With fixed-ram (new): --------------------- -------------------------------- | ramblock 1 header | | ramblock 1 header | --------------------- -------------------------------- | ramblock 2 header | | ramblock 1 fixed-ram header | --------------------- -------------------------------- | ... | | padding to next 1MB boundary | --------------------- | ... | | ramblock n header | -------------------------------- --------------------- | ramblock 1 pages | | RAM_SAVE_FLAG_EOS | | ... | --------------------- -------------------------------- | stream of pages | | ramblock 2 header | | (iter 1) | -------------------------------- | ... | | ramblock 2 fixed-ram header | --------------------- -------------------------------- | RAM_SAVE_FLAG_EOS | | padding to next 1MB boundary | --------------------- | ... | | stream of pages | -------------------------------- | (iter 2) | | ramblock 2 pages | | ... | | ... | --------------------- -------------------------------- | ... | | ... | --------------------- -------------------------------- | RAM_SAVE_FLAG_EOS | -------------------------------- | ... | -------------------------------- where: - ramblock header: the generic information for a ramblock, such as idstr, used_len, etc. - ramblock fixed-ram header: the new information added by this feature: bitmap of pages written, bitmap size and offset of pages in the migration file. Signed-off-by: Nikolay Borisov Signed-off-by: Fabiano Rosas --- - used a macro for alignment value - documented alignment assumptions - moved shadow_bmap debug code to multifd patch - did NOT use used_length for bmap, it breaks dirty page tracking somehow - uncommented the capability enabling - accounted for the bitmap size with ram_transferred_add() --- include/exec/ramblock.h | 8 +++ migration/ram.c | 121 +++++++++++++++++++++++++++++++++++++--- 2 files changed, 120 insertions(+), 9 deletions(-) diff --git a/include/exec/ramblock.h b/include/exec/ramblock.h index 69c6a53902..e0e3f16852 100644 --- a/include/exec/ramblock.h +++ b/include/exec/ramblock.h @@ -44,6 +44,14 @@ struct RAMBlock { size_t page_size; /* dirty bitmap used during migration */ unsigned long *bmap; + /* shadow dirty bitmap used when migrating to a file */ + unsigned long *shadow_bmap; + /* + * offset in the file pages belonging to this ramblock are saved, + * used only during migration to a file. + */ + off_t bitmap_offset; + uint64_t pages_offset; /* bitmap of already received pages in postcopy */ unsigned long *receivedmap; diff --git a/migration/ram.c b/migration/ram.c index 8c7886ab79..4a0ab8105f 100644 --- a/migration/ram.c +++ b/migration/ram.c @@ -94,6 +94,18 @@ #define RAM_SAVE_FLAG_MULTIFD_FLUSH 0x200 /* We can't use any flag that is bigger than 0x200 */ +/* + * fixed-ram migration supports O_DIRECT, so we need to make sure the + * userspace buffer, the IO operation size and the file offset are + * aligned according to the underlying device's block size. The first + * two are already aligned to page size, but we need to add padding to + * the file to align the offset. We cannot read the block size + * dynamically because the migration file can be moved between + * different systems, so use 1M to cover most block sizes and to keep + * the file offset aligned at page size as well. + */ +#define FIXED_RAM_FILE_OFFSET_ALIGNMENT 0x100000 + XBZRLECacheStats xbzrle_counters; /* used by the search for pages to send */ @@ -1127,12 +1139,18 @@ static int save_zero_page(RAMState *rs, PageSearchStatus *pss, return 0; } + stat64_add(&mig_stats.zero_pages, 1); + + if (migrate_fixed_ram()) { + /* zero pages are not transferred with fixed-ram */ + clear_bit(offset >> TARGET_PAGE_BITS, pss->block->shadow_bmap); + return 1; + } + len += save_page_header(pss, file, pss->block, offset | RAM_SAVE_FLAG_ZERO); qemu_put_byte(file, 0); len += 1; ram_release_page(pss->block->idstr, offset); - - stat64_add(&mig_stats.zero_pages, 1); ram_transferred_add(len); /* @@ -1190,14 +1208,20 @@ static int save_normal_page(PageSearchStatus *pss, RAMBlock *block, { QEMUFile *file = pss->pss_channel; - ram_transferred_add(save_page_header(pss, pss->pss_channel, block, - offset | RAM_SAVE_FLAG_PAGE)); - if (async) { - qemu_put_buffer_async(file, buf, TARGET_PAGE_SIZE, - migrate_release_ram() && - migration_in_postcopy()); + if (migrate_fixed_ram()) { + qemu_put_buffer_at(file, buf, TARGET_PAGE_SIZE, + block->pages_offset + offset); + set_bit(offset >> TARGET_PAGE_BITS, block->shadow_bmap); } else { - qemu_put_buffer(file, buf, TARGET_PAGE_SIZE); + ram_transferred_add(save_page_header(pss, pss->pss_channel, block, + offset | RAM_SAVE_FLAG_PAGE)); + if (async) { + qemu_put_buffer_async(file, buf, TARGET_PAGE_SIZE, + migrate_release_ram() && + migration_in_postcopy()); + } else { + qemu_put_buffer(file, buf, TARGET_PAGE_SIZE); + } } ram_transferred_add(TARGET_PAGE_SIZE); stat64_add(&mig_stats.normal_pages, 1); @@ -2413,6 +2437,8 @@ static void ram_save_cleanup(void *opaque) block->clear_bmap = NULL; g_free(block->bmap); block->bmap = NULL; + g_free(block->shadow_bmap); + block->shadow_bmap = NULL; } xbzrle_cleanup(); @@ -2780,6 +2806,7 @@ static void ram_list_init_bitmaps(void) */ block->bmap = bitmap_new(pages); bitmap_set(block->bmap, 0, pages); + block->shadow_bmap = bitmap_new(pages); block->clear_bmap_shift = shift; block->clear_bmap = bitmap_new(clear_bmap_size(pages, shift)); } @@ -2917,6 +2944,58 @@ void qemu_guest_free_page_hint(void *addr, size_t len) } } +#define FIXED_RAM_HDR_VERSION 1 +struct FixedRamHeader { + uint32_t version; + /* + * The target's page size, so we know how many pages are in the + * bitmap. + */ + uint64_t page_size; + /* + * The offset in the migration file where the pages bitmap is + * found. + */ + uint64_t bitmap_offset; + /* + * The offset in the migration file where the actual pages (data) + * are found. + */ + uint64_t pages_offset; + /* end of v1 */ +} QEMU_PACKED; +typedef struct FixedRamHeader FixedRamHeader; + +static void fixed_ram_insert_header(QEMUFile *file, RAMBlock *block) +{ + g_autofree FixedRamHeader *header; + size_t header_size, bitmap_size; + long num_pages; + + header = g_new0(FixedRamHeader, 1); + header_size = sizeof(FixedRamHeader); + + num_pages = block->used_length >> TARGET_PAGE_BITS; + bitmap_size = BITS_TO_LONGS(num_pages) * sizeof(unsigned long); + + /* + * Save the file offsets of where the bitmap and the pages should + * go as they are written at the end of migration and during the + * iterative phase, respectively. + */ + block->bitmap_offset = qemu_get_offset(file) + header_size; + block->pages_offset = ROUND_UP(block->bitmap_offset + + bitmap_size, + FIXED_RAM_FILE_OFFSET_ALIGNMENT); + + header->version = cpu_to_be32(FIXED_RAM_HDR_VERSION); + header->page_size = cpu_to_be64(TARGET_PAGE_SIZE); + header->bitmap_offset = cpu_to_be64(block->bitmap_offset); + header->pages_offset = cpu_to_be64(block->pages_offset); + + qemu_put_buffer(file, (uint8_t *) header, header_size); +} + /* * Each of ram_save_setup, ram_save_iterate and ram_save_complete has * long-running RCU critical section. When rcu-reclaims in the code @@ -2966,6 +3045,13 @@ static int ram_save_setup(QEMUFile *f, void *opaque) if (migrate_ignore_shared()) { qemu_put_be64(f, block->mr->addr); } + + if (migrate_fixed_ram()) { + fixed_ram_insert_header(f, block); + /* prepare offset for next ramblock */ + qemu_set_offset(f, block->pages_offset + block->used_length, + SEEK_SET); + } } } @@ -2999,6 +3085,19 @@ static int ram_save_setup(QEMUFile *f, void *opaque) return qemu_fflush(f); } +static void ram_save_shadow_bmap(QEMUFile *f) +{ + RAMBlock *block; + + RAMBLOCK_FOREACH_MIGRATABLE(block) { + long num_pages = block->used_length >> TARGET_PAGE_BITS; + long bitmap_size = BITS_TO_LONGS(num_pages) * sizeof(unsigned long); + qemu_put_buffer_at(f, (uint8_t *)block->shadow_bmap, bitmap_size, + block->bitmap_offset); + ram_transferred_add(bitmap_size); + } +} + /** * ram_save_iterate: iterative stage for migration * @@ -3188,6 +3287,10 @@ static int ram_save_complete(QEMUFile *f, void *opaque) return ret; } + if (migrate_fixed_ram()) { + ram_save_shadow_bmap(f); + } + if (migrate_multifd() && !migrate_multifd_flush_after_each_section()) { qemu_put_be64(f, RAM_SAVE_FLAG_MULTIFD_FLUSH); }