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Date: Fri, 16 Feb 2024 22:39:58 +0000 Message-Id: <20240216224002.1476890-4-hao.xiang@bytedance.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20240216224002.1476890-1-hao.xiang@bytedance.com> References: <20240216224002.1476890-1-hao.xiang@bytedance.com> MIME-Version: 1.0 Received-SPF: pass client-ip=2607:f8b0:4864:20::a2c; envelope-from=hao.xiang@bytedance.com; helo=mail-vk1-xa2c.google.com 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, RCVD_IN_DNSWL_NONE=-0.0001, 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+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org 1. Implements the zero page detection and handling on the multifd threads for non-compression, zlib and zstd compression backends. 2. Added a new value 'multifd' in ZeroPageDetection enumeration. 3. Add proper asserts to ensure pages->normal are used for normal pages in all scenarios. Signed-off-by: Hao Xiang --- migration/meson.build | 1 + migration/multifd-zero-page.c | 59 +++++++++++++++++++++++++++++++++++ migration/multifd-zlib.c | 26 ++++++++++++--- migration/multifd-zstd.c | 25 ++++++++++++--- migration/multifd.c | 50 +++++++++++++++++++++++------ migration/multifd.h | 7 +++++ qapi/migration.json | 4 ++- 7 files changed, 151 insertions(+), 21 deletions(-) create mode 100644 migration/multifd-zero-page.c diff --git a/migration/meson.build b/migration/meson.build index 92b1cc4297..1eeb915ff6 100644 --- a/migration/meson.build +++ b/migration/meson.build @@ -22,6 +22,7 @@ system_ss.add(files( 'migration.c', 'multifd.c', 'multifd-zlib.c', + 'multifd-zero-page.c', 'ram-compress.c', 'options.c', 'postcopy-ram.c', diff --git a/migration/multifd-zero-page.c b/migration/multifd-zero-page.c new file mode 100644 index 0000000000..f0cd8e2c53 --- /dev/null +++ b/migration/multifd-zero-page.c @@ -0,0 +1,59 @@ +/* + * Multifd zero page detection implementation. + * + * Copyright (c) 2024 Bytedance Inc + * + * Authors: + * Hao Xiang + * + * This work is licensed under the terms of the GNU GPL, version 2 or later. + * See the COPYING file in the top-level directory. + */ + +#include "qemu/osdep.h" +#include "qemu/cutils.h" +#include "exec/ramblock.h" +#include "migration.h" +#include "multifd.h" +#include "options.h" +#include "ram.h" + +void multifd_zero_page_check_send(MultiFDSendParams *p) +{ + /* + * QEMU older than 9.0 don't understand zero page + * on multifd channel. This switch is required to + * maintain backward compatibility. + */ + bool use_multifd_zero_page = + (migrate_zero_page_detection() == ZERO_PAGE_DETECTION_MULTIFD); + MultiFDPages_t *pages = p->pages; + RAMBlock *rb = pages->block; + + assert(pages->num != 0); + assert(pages->normal_num == 0); + assert(pages->zero_num == 0); + + for (int i = 0; i < pages->num; i++) { + uint64_t offset = pages->offset[i]; + if (use_multifd_zero_page && + buffer_is_zero(rb->host + offset, p->page_size)) { + pages->zero[pages->zero_num] = offset; + pages->zero_num++; + ram_release_page(rb->idstr, offset); + } else { + pages->normal[pages->normal_num] = offset; + pages->normal_num++; + } + } +} + +void multifd_zero_page_check_recv(MultiFDRecvParams *p) +{ + for (int i = 0; i < p->zero_num; i++) { + void *page = p->host + p->zero[i]; + if (!buffer_is_zero(page, p->page_size)) { + memset(page, 0, p->page_size); + } + } +} diff --git a/migration/multifd-zlib.c b/migration/multifd-zlib.c index 012e3bdea1..cdfe0fa70e 100644 --- a/migration/multifd-zlib.c +++ b/migration/multifd-zlib.c @@ -123,13 +123,20 @@ static int zlib_send_prepare(MultiFDSendParams *p, Error **errp) int ret; uint32_t i; + multifd_zero_page_check_send(p); + + if (!pages->normal_num) { + p->next_packet_size = 0; + goto out; + } + multifd_send_prepare_header(p); - for (i = 0; i < pages->num; i++) { + for (i = 0; i < pages->normal_num; i++) { uint32_t available = z->zbuff_len - out_size; int flush = Z_NO_FLUSH; - if (i == pages->num - 1) { + if (i == pages->normal_num - 1) { flush = Z_SYNC_FLUSH; } @@ -138,7 +145,7 @@ static int zlib_send_prepare(MultiFDSendParams *p, Error **errp) * with compression. zlib does not guarantee that this is safe, * therefore copy the page before calling deflate(). */ - memcpy(z->buf, p->pages->block->host + pages->offset[i], p->page_size); + memcpy(z->buf, p->pages->block->host + pages->normal[i], p->page_size); zs->avail_in = p->page_size; zs->next_in = z->buf; @@ -172,10 +179,10 @@ static int zlib_send_prepare(MultiFDSendParams *p, Error **errp) p->iov[p->iovs_num].iov_len = out_size; p->iovs_num++; p->next_packet_size = out_size; - p->flags |= MULTIFD_FLAG_ZLIB; +out: + p->flags |= MULTIFD_FLAG_ZLIB; multifd_send_fill_packet(p); - return 0; } @@ -261,6 +268,14 @@ static int zlib_recv_pages(MultiFDRecvParams *p, Error **errp) p->id, flags, MULTIFD_FLAG_ZLIB); return -1; } + + multifd_zero_page_check_recv(p); + + if (!p->normal_num) { + assert(in_size == 0); + return 0; + } + ret = qio_channel_read_all(p->c, (void *)z->zbuff, in_size, errp); if (ret != 0) { @@ -310,6 +325,7 @@ static int zlib_recv_pages(MultiFDRecvParams *p, Error **errp) p->id, out_size, expected_size); return -1; } + return 0; } diff --git a/migration/multifd-zstd.c b/migration/multifd-zstd.c index dc8fe43e94..27a1eba075 100644 --- a/migration/multifd-zstd.c +++ b/migration/multifd-zstd.c @@ -118,19 +118,26 @@ static int zstd_send_prepare(MultiFDSendParams *p, Error **errp) int ret; uint32_t i; + multifd_zero_page_check_send(p); + + if (!pages->normal_num) { + p->next_packet_size = 0; + goto out; + } + multifd_send_prepare_header(p); z->out.dst = z->zbuff; z->out.size = z->zbuff_len; z->out.pos = 0; - for (i = 0; i < pages->num; i++) { + for (i = 0; i < pages->normal_num; i++) { ZSTD_EndDirective flush = ZSTD_e_continue; - if (i == pages->num - 1) { + if (i == pages->normal_num - 1) { flush = ZSTD_e_flush; } - z->in.src = p->pages->block->host + pages->offset[i]; + z->in.src = p->pages->block->host + pages->normal[i]; z->in.size = p->page_size; z->in.pos = 0; @@ -161,10 +168,10 @@ static int zstd_send_prepare(MultiFDSendParams *p, Error **errp) p->iov[p->iovs_num].iov_len = z->out.pos; p->iovs_num++; p->next_packet_size = z->out.pos; - p->flags |= MULTIFD_FLAG_ZSTD; +out: + p->flags |= MULTIFD_FLAG_ZSTD; multifd_send_fill_packet(p); - return 0; } @@ -257,6 +264,14 @@ static int zstd_recv_pages(MultiFDRecvParams *p, Error **errp) p->id, flags, MULTIFD_FLAG_ZSTD); return -1; } + + multifd_zero_page_check_recv(p); + + if (!p->normal_num) { + assert(in_size == 0); + return 0; + } + ret = qio_channel_read_all(p->c, (void *)z->zbuff, in_size, errp); if (ret != 0) { diff --git a/migration/multifd.c b/migration/multifd.c index a33dba40d9..fbb40ea10b 100644 --- a/migration/multifd.c +++ b/migration/multifd.c @@ -11,6 +11,7 @@ */ #include "qemu/osdep.h" +#include "qemu/cutils.h" #include "qemu/rcu.h" #include "exec/target_page.h" #include "sysemu/sysemu.h" @@ -126,6 +127,8 @@ static int nocomp_send_prepare(MultiFDSendParams *p, Error **errp) MultiFDPages_t *pages = p->pages; int ret; + multifd_zero_page_check_send(p); + if (!use_zero_copy_send) { /* * Only !zerocopy needs the header in IOV; zerocopy will @@ -134,13 +137,13 @@ static int nocomp_send_prepare(MultiFDSendParams *p, Error **errp) multifd_send_prepare_header(p); } - for (int i = 0; i < pages->num; i++) { - p->iov[p->iovs_num].iov_base = pages->block->host + pages->offset[i]; + for (int i = 0; i < pages->normal_num; i++) { + p->iov[p->iovs_num].iov_base = pages->block->host + pages->normal[i]; p->iov[p->iovs_num].iov_len = p->page_size; p->iovs_num++; } - p->next_packet_size = pages->num * p->page_size; + p->next_packet_size = pages->normal_num * p->page_size; p->flags |= MULTIFD_FLAG_NOCOMP; multifd_send_fill_packet(p); @@ -202,6 +205,13 @@ static int nocomp_recv_pages(MultiFDRecvParams *p, Error **errp) p->id, flags, MULTIFD_FLAG_NOCOMP); return -1; } + + multifd_zero_page_check_recv(p); + + if (!p->normal_num) { + return 0; + } + for (int i = 0; i < p->normal_num; i++) { p->iov[i].iov_base = p->host + p->normal[i]; p->iov[i].iov_len = p->page_size; @@ -339,7 +349,7 @@ void multifd_send_fill_packet(MultiFDSendParams *p) packet->flags = cpu_to_be32(p->flags); packet->pages_alloc = cpu_to_be32(p->pages->allocated); - packet->normal_pages = cpu_to_be32(pages->num); + packet->normal_pages = cpu_to_be32(pages->normal_num); packet->zero_pages = cpu_to_be32(pages->zero_num); packet->next_packet_size = cpu_to_be32(p->next_packet_size); @@ -350,18 +360,25 @@ void multifd_send_fill_packet(MultiFDSendParams *p) strncpy(packet->ramblock, pages->block->idstr, 256); } - for (i = 0; i < pages->num; i++) { + for (i = 0; i < pages->normal_num; i++) { /* there are architectures where ram_addr_t is 32 bit */ - uint64_t temp = pages->offset[i]; + uint64_t temp = pages->normal[i]; packet->offset[i] = cpu_to_be64(temp); } + for (i = 0; i < pages->zero_num; i++) { + /* there are architectures where ram_addr_t is 32 bit */ + uint64_t temp = pages->zero[i]; + + packet->offset[pages->normal_num + i] = cpu_to_be64(temp); + } + p->packets_sent++; - p->total_normal_pages += pages->num; + p->total_normal_pages += pages->normal_num; p->total_zero_pages += pages->zero_num; - trace_multifd_send(p->id, packet_num, pages->num, pages->zero_num, + trace_multifd_send(p->id, packet_num, pages->normal_num, pages->zero_num, p->flags, p->next_packet_size); } @@ -451,6 +468,18 @@ static int multifd_recv_unfill_packet(MultiFDRecvParams *p, Error **errp) p->normal[i] = offset; } + for (i = 0; i < p->zero_num; i++) { + uint64_t offset = be64_to_cpu(packet->offset[p->normal_num + i]); + + if (offset > (p->block->used_length - p->page_size)) { + error_setg(errp, "multifd: offset too long %" PRIu64 + " (max " RAM_ADDR_FMT ")", + offset, p->block->used_length); + return -1; + } + p->zero[i] = offset; + } + return 0; } @@ -842,7 +871,7 @@ static void *multifd_send_thread(void *opaque) stat64_add(&mig_stats.multifd_bytes, p->next_packet_size + p->packet_len); - stat64_add(&mig_stats.normal_pages, pages->num); + stat64_add(&mig_stats.normal_pages, pages->normal_num); stat64_add(&mig_stats.zero_pages, pages->zero_num); multifd_pages_reset(p->pages); @@ -1256,7 +1285,8 @@ static void *multifd_recv_thread(void *opaque) p->flags &= ~MULTIFD_FLAG_SYNC; qemu_mutex_unlock(&p->mutex); - if (p->normal_num) { + if (p->normal_num + p->zero_num) { + assert(!(flags & MULTIFD_FLAG_SYNC)); ret = multifd_recv_state->ops->recv_pages(p, &local_err); if (ret != 0) { break; diff --git a/migration/multifd.h b/migration/multifd.h index 9822ff298a..125f0bbe60 100644 --- a/migration/multifd.h +++ b/migration/multifd.h @@ -53,6 +53,11 @@ typedef struct { uint32_t unused32[1]; /* Reserved for future use */ uint64_t unused64[3]; /* Reserved for future use */ char ramblock[256]; + /* + * This array contains the pointers to: + * - normal pages (initial normal_pages entries) + * - zero pages (following zero_pages entries) + */ uint64_t offset[]; } __attribute__((packed)) MultiFDPacket_t; @@ -224,6 +229,8 @@ typedef struct { void multifd_register_ops(int method, MultiFDMethods *ops); void multifd_send_fill_packet(MultiFDSendParams *p); +void multifd_zero_page_check_send(MultiFDSendParams *p); +void multifd_zero_page_check_recv(MultiFDRecvParams *p); static inline void multifd_send_prepare_header(MultiFDSendParams *p) { diff --git a/qapi/migration.json b/qapi/migration.json index 99843a8e95..e2450b92d4 100644 --- a/qapi/migration.json +++ b/qapi/migration.json @@ -660,9 +660,11 @@ # # @none: Do not perform zero page checking. # +# @multifd: Perform zero page checking on the multifd sender thread. (since 9.0) +# ## { 'enum': 'ZeroPageDetection', - 'data': [ 'legacy', 'none' ] } + 'data': [ 'legacy', 'none', 'multifd' ] } ## # @BitmapMigrationBitmapAliasTransform: