[v3,2/7] migration/multifd: Implement zero page transmission on the multifd thread.

Message ID	20240226195654.934709-3-hao.xiang@bytedance.com (mailing list archive)
State	New, archived
Headers	show Return-Path: <qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org> From: Hao Xiang <hao.xiang@bytedance.com> To: pbonzini@redhat.com, berrange@redhat.com, eduardo@habkost.net, peterx@redhat.com, farosas@suse.de, eblake@redhat.com, armbru@redhat.com, thuth@redhat.com, lvivier@redhat.com, jdenemar@redhat.com, marcel.apfelbaum@gmail.com, philmd@linaro.org, wangyanan55@huawei.com, qemu-devel@nongnu.org Cc: Hao Xiang <hao.xiang@bytedance.com> Subject: [PATCH v3 2/7] migration/multifd: Implement zero page transmission on the multifd thread. Date: Mon, 26 Feb 2024 19:56:49 +0000 Message-Id: <20240226195654.934709-3-hao.xiang@bytedance.com> In-Reply-To: <20240226195654.934709-1-hao.xiang@bytedance.com> References: <20240226195654.934709-1-hao.xiang@bytedance.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=2607:f8b0:4864:20::a2b; envelope-from=hao.xiang@bytedance.com; helo=mail-vk1-xa2b.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 Precedence: list Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org
Series	Introduce multifd zero page checking. \| expand [v3,0/7] Introduce multifd zero page checking. [v3,1/7] migration/multifd: Add new migration option zero-page-detection. [v3,2/7] migration/multifd: Implement zero page transmission on the multifd thread. [v3,3/7] migration/multifd: Implement ram_save_target_page_multifd to handle multifd version of Mig… [v3,4/7] migration/multifd: Enable multifd zero page checking by default. [v3,5/7] migration/multifd: Add new migration test cases for legacy zero page checking. [v3,6/7] migration/multifd: Add zero pages and zero bytes counter to migration status interface. [v3,7/7] Update maintainer contact for migration multifd zero page checking acceleration.

diff --git a/hw/core/machine.c b/hw/core/machine.c index fb5afdcae4..746da219a4 100644 --- a/hw/core/machine.c +++ b/hw/core/machine.c @@ -32,7 +32,9 @@ #include "hw/virtio/virtio-net.h" #include "audio/audio.h" -GlobalProperty hw_compat_8_2[] = {}; +GlobalProperty hw_compat_8_2[] = { + { "migration", "zero-page-detection", "legacy"}, +}; const size_t hw_compat_8_2_len = G_N_ELEMENTS(hw_compat_8_2); GlobalProperty hw_compat_8_1[] = { diff --git a/hw/core/qdev-properties-system.c b/hw/core/qdev-properties-system.c index 228e685f52..6e6f68ae1b 100644 --- a/hw/core/qdev-properties-system.c +++ b/hw/core/qdev-properties-system.c @@ -682,7 +682,7 @@ const PropertyInfo qdev_prop_mig_mode = { const PropertyInfo qdev_prop_zero_page_detection = { .name = "ZeroPageDetection", .description = "zero_page_detection values, " - "none,legacy", + "none,legacy,multifd", .enum_table = &ZeroPageDetection_lookup, .get = qdev_propinfo_get_enum, .set = qdev_propinfo_set_enum, 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..1650c41b26 --- /dev/null +++ b/migration/multifd-zero-page.c @@ -0,0 +1,78 @@ +/* + * Multifd zero page detection implementation. + * + * Copyright (c) 2024 Bytedance Inc + * + * Authors: + * Hao Xiang <hao.xiang@bytedance.com> + * + * 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" + +static void swap_page_offset(ram_addr_t *pages_offset, int a, int b) +{ + ram_addr_t temp; + + if (a == b) { + return; + } + + temp = pages_offset[a]; + pages_offset[a] = pages_offset[b]; + pages_offset[b] = temp; +} + +/** + * multifd_zero_page_check_send: Perform zero page detection on all pages. + * + * Sort the page offset array by moving all normal pages to + * the left and all zero pages to the right of the array. + * + * @param p A pointer to the send params. + */ +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; + int index_normal = 0; + int index_zero = pages->num - 1; + + while (index_normal <= index_zero) { + uint64_t offset = pages->offset[index_normal]; + if (use_multifd_zero_page && + buffer_is_zero(rb->host + offset, p->page_size)) { + swap_page_offset(pages->offset, index_normal, index_zero); + index_zero--; + ram_release_page(rb->idstr, offset); + } else { + index_normal++; + 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..a8b26bc5e4 100644 --- a/migration/multifd-zlib.c +++ b/migration/multifd-zlib.c @@ -123,13 +123,15 @@ static int zlib_send_prepare(MultiFDSendParams *p, Error **errp) int ret; uint32_t i; - multifd_send_prepare_header(p); + if (!multifd_send_prepare_common(p)) { + goto out; + } - 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; } @@ -172,10 +174,10 @@ 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 +263,14 @@ 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 +320,7 @@ 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..7768040124 100644 --- a/migration/multifd-zstd.c +++ b/migration/multifd-zstd.c @@ -118,16 +118,18 @@ static int zstd_send_prepare(MultiFDSendParams *p, Error **errp) int ret; uint32_t i; - multifd_send_prepare_header(p); + if (!multifd_send_prepare_common(p)) { + goto out; + } 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]; @@ -161,10 +163,10 @@ 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 +259,14 @@ 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 adfe8c9a0a..eace0278af 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++) { + for (int i = 0; i < pages->normal_num; i++) { p->iov[p->iovs_num].iov_base = pages->block->host + pages->offset[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; @@ -236,6 +246,7 @@ static void multifd_pages_reset(MultiFDPages_t *pages) * overwritten later when reused. */ pages->num = 0; + pages->normal_num = 0; pages->block = NULL; } @@ -327,11 +338,13 @@ void multifd_send_fill_packet(MultiFDSendParams *p) MultiFDPacket_t *packet = p->packet; MultiFDPages_t *pages = p->pages; uint64_t packet_num; + uint32_t zero_num = pages->num - pages->normal_num; int i; 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(zero_num); packet->next_packet_size = cpu_to_be32(p->next_packet_size); packet_num = qatomic_fetch_inc(&multifd_send_state->packet_num); @@ -349,10 +362,11 @@ void multifd_send_fill_packet(MultiFDSendParams *p) } p->packets_sent++; - p->total_normal_pages += pages->num; + p->total_normal_pages += pages->normal_num; + p->total_zero_pages += zero_num; - trace_multifd_send(p->id, packet_num, pages->num, p->flags, - p->next_packet_size); + trace_multifd_send(p->id, packet_num, pages->normal_num, zero_num, + p->flags, p->next_packet_size); } static int multifd_recv_unfill_packet(MultiFDRecvParams *p, Error **errp) @@ -393,20 +407,29 @@ static int multifd_recv_unfill_packet(MultiFDRecvParams *p, Error **errp) p->normal_num = be32_to_cpu(packet->normal_pages); if (p->normal_num > packet->pages_alloc) { error_setg(errp, "multifd: received packet " - "with %u pages and expected maximum pages are %u", + "with %u normal pages and expected maximum pages are %u", p->normal_num, packet->pages_alloc) ; return -1; } + p->zero_num = be32_to_cpu(packet->zero_pages); + if (p->zero_num > packet->pages_alloc - p->normal_num) { + error_setg(errp, "multifd: received packet " + "with %u zero pages and expected maximum zero pages are %u", + p->zero_num, packet->pages_alloc - p->normal_num) ; + return -1; + } + p->next_packet_size = be32_to_cpu(packet->next_packet_size); p->packet_num = be64_to_cpu(packet->packet_num); p->packets_recved++; p->total_normal_pages += p->normal_num; + p->total_zero_pages += p->zero_num; - trace_multifd_recv(p->id, p->packet_num, p->normal_num, p->flags, - p->next_packet_size); + trace_multifd_recv(p->id, p->packet_num, p->normal_num, p->zero_num, + p->flags, p->next_packet_size); - if (p->normal_num == 0) { + if (p->normal_num == 0 && p->zero_num == 0) { return 0; } @@ -432,6 +455,18 @@ 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; } @@ -823,6 +858,8 @@ 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->normal_num); + stat64_add(&mig_stats.zero_pages, pages->num - pages->normal_num); multifd_pages_reset(p->pages); p->next_packet_size = 0; @@ -866,7 +903,8 @@ out: rcu_unregister_thread(); migration_threads_remove(thread); - trace_multifd_send_thread_end(p->id, p->packets_sent, p->total_normal_pages); + trace_multifd_send_thread_end(p->id, p->packets_sent, p->total_normal_pages, + p->total_zero_pages); return NULL; } @@ -1132,6 +1170,8 @@ static void multifd_recv_cleanup_channel(MultiFDRecvParams *p) p->iov = NULL; g_free(p->normal); p->normal = NULL; + g_free(p->zero); + p->zero = NULL; multifd_recv_state->ops->recv_cleanup(p); } @@ -1232,7 +1272,7 @@ 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) { ret = multifd_recv_state->ops->recv_pages(p, &local_err); if (ret != 0) { break; @@ -1251,7 +1291,9 @@ static void *multifd_recv_thread(void *opaque) } rcu_unregister_thread(); - trace_multifd_recv_thread_end(p->id, p->packets_recved, p->total_normal_pages); + trace_multifd_recv_thread_end(p->id, p->packets_recved, + p->total_normal_pages, + p->total_zero_pages); return NULL; } @@ -1290,6 +1332,7 @@ int multifd_recv_setup(Error **errp) p->name = g_strdup_printf("multifdrecv_%d", i); p->iov = g_new0(struct iovec, page_count); p->normal = g_new0(ram_addr_t, page_count); + p->zero = g_new0(ram_addr_t, page_count); p->page_count = page_count; p->page_size = qemu_target_page_size(); } @@ -1359,3 +1402,17 @@ void multifd_recv_new_channel(QIOChannel *ioc, Error **errp) QEMU_THREAD_JOINABLE); qatomic_inc(&multifd_recv_state->count); } + +bool multifd_send_prepare_common(MultiFDSendParams *p) +{ + multifd_zero_page_check_send(p); + + if (!p->pages->normal_num) { + p->next_packet_size = 0; + return false; + } + + multifd_send_prepare_header(p); + + return true; +} diff --git a/migration/multifd.h b/migration/multifd.h index 8a1cad0996..e18ffdf7cc 100644 --- a/migration/multifd.h +++ b/migration/multifd.h @@ -48,14 +48,24 @@ typedef struct { /* size of the next packet that contains pages */ uint32_t next_packet_size; uint64_t packet_num; - uint64_t unused[4]; /* Reserved for future use */ + /* zero pages */ + uint32_t zero_pages; + 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; typedef struct { /* number of used pages */ uint32_t num; + /* number of normal pages */ + uint32_t normal_num; /* number of allocated pages */ uint32_t allocated; /* offset of each page */ @@ -124,6 +134,8 @@ typedef struct { uint64_t packets_sent; /* non zero pages sent through this channel */ uint64_t total_normal_pages; + /* zero pages sent through this channel */ + uint64_t total_zero_pages; /* buffers to send */ struct iovec *iov; /* number of iovs used */ @@ -178,12 +190,18 @@ typedef struct { uint8_t *host; /* non zero pages recv through this channel */ uint64_t total_normal_pages; + /* zero pages recv through this channel */ + uint64_t total_zero_pages; /* buffers to recv */ struct iovec *iov; /* Pages that are not zero */ ram_addr_t *normal; /* num of non zero pages */ uint32_t normal_num; + /* Pages that are zero */ + ram_addr_t *zero; + /* num of zero pages */ + uint32_t zero_num; /* used for de-compression methods */ void *data; } MultiFDRecvParams; @@ -205,6 +223,9 @@ typedef struct { void multifd_register_ops(int method, MultiFDMethods *ops); void multifd_send_fill_packet(MultiFDSendParams *p); +bool multifd_send_prepare_common(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) { @@ -213,5 +234,4 @@ static inline void multifd_send_prepare_header(MultiFDSendParams *p) p->iovs_num++; } - #endif diff --git a/migration/ram.c b/migration/ram.c index 67035fb4b1..414cd0d753 100644 --- a/migration/ram.c +++ b/migration/ram.c @@ -1259,7 +1259,6 @@ static int ram_save_multifd_page(RAMBlock *block, ram_addr_t offset) if (!multifd_queue_page(block, offset)) { return -1; } - stat64_add(&mig_stats.normal_pages, 1); return 1; } diff --git a/migration/trace-events b/migration/trace-events index 298ad2b0dd..9f1d7ae71a 100644 --- a/migration/trace-events +++ b/migration/trace-events @@ -128,21 +128,21 @@ postcopy_preempt_reset_channel(void) "" # multifd.c multifd_new_send_channel_async(uint8_t id) "channel %u" multifd_new_send_channel_async_error(uint8_t id, void *err) "channel=%u err=%p" -multifd_recv(uint8_t id, uint64_t packet_num, uint32_t used, uint32_t flags, uint32_t next_packet_size) "channel %u packet_num %" PRIu64 " pages %u flags 0x%x next packet size %u" +multifd_recv(uint8_t id, uint64_t packet_num, uint32_t normal, uint32_t zero, uint32_t flags, uint32_t next_packet_size) "channel %u packet_num %" PRIu64 " normal pages %u zero pages %u flags 0x%x next packet size %u" multifd_recv_new_channel(uint8_t id) "channel %u" multifd_recv_sync_main(long packet_num) "packet num %ld" multifd_recv_sync_main_signal(uint8_t id) "channel %u" multifd_recv_sync_main_wait(uint8_t id) "channel %u" multifd_recv_terminate_threads(bool error) "error %d" -multifd_recv_thread_end(uint8_t id, uint64_t packets, uint64_t pages) "channel %u packets %" PRIu64 " pages %" PRIu64 +multifd_recv_thread_end(uint8_t id, uint64_t packets, uint64_t normal_pages, uint64_t zero_pages) "channel %u packets %" PRIu64 " normal pages %" PRIu64 " zero pages %" PRIu64 multifd_recv_thread_start(uint8_t id) "%u" -multifd_send(uint8_t id, uint64_t packet_num, uint32_t normal, uint32_t flags, uint32_t next_packet_size) "channel %u packet_num %" PRIu64 " normal pages %u flags 0x%x next packet size %u" +multifd_send(uint8_t id, uint64_t packet_num, uint32_t normal_pages, uint32_t zero_pages, uint32_t flags, uint32_t next_packet_size) "channel %u packet_num %" PRIu64 " normal pages %u zero pages %u flags 0x%x next packet size %u" multifd_send_error(uint8_t id) "channel %u" multifd_send_sync_main(long packet_num) "packet num %ld" multifd_send_sync_main_signal(uint8_t id) "channel %u" multifd_send_sync_main_wait(uint8_t id) "channel %u" multifd_send_terminate_threads(void) "" -multifd_send_thread_end(uint8_t id, uint64_t packets, uint64_t normal_pages) "channel %u packets %" PRIu64 " normal pages %" PRIu64 +multifd_send_thread_end(uint8_t id, uint64_t packets, uint64_t normal_pages, uint64_t zero_pages) "channel %u packets %" PRIu64 " normal pages %" PRIu64 " zero pages %" PRIu64 multifd_send_thread_start(uint8_t id) "%u" multifd_tls_outgoing_handshake_start(void *ioc, void *tioc, const char *hostname) "ioc=%p tioc=%p hostname=%s" multifd_tls_outgoing_handshake_error(void *ioc, const char *err) "ioc=%p err=%s" diff --git a/qapi/migration.json b/qapi/migration.json index 1e66272f8f..5a1bb8ad62 100644 --- a/qapi/migration.json +++ b/qapi/migration.json @@ -660,10 +660,13 @@ # # @legacy: Perform zero page checking from main migration thread. # +# @multifd: Perform zero page checking from multifd sender thread. +# # Since: 9.0 +# ## { 'enum': 'ZeroPageDetection', - 'data': [ 'none', 'legacy' ] } + 'data': [ 'none', 'legacy', 'multifd' ] } ## # @BitmapMigrationBitmapAliasTransform:

[v3,2/7] migration/multifd: Implement zero page transmission on the multifd thread.

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