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[99.254.121.117]) by smtp.gmail.com with ESMTPSA id ks15-20020ac8620f000000b0043a5edf024dsm5779489qtb.35.2024.05.01.12.25.27 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 01 May 2024 12:25:27 -0700 (PDT) Date: Wed, 1 May 2024 15:25:26 -0400 From: Peter Xu To: Hao Xiang Cc: marcandre.lureau@redhat.com, farosas@suse.de, armbru@redhat.com, lvivier@redhat.com, qemu-devel@nongnu.org Subject: Re: [PATCH v4 10/14] migration/multifd: Enable DSA offloading in multifd sender path. Message-ID: References: <20240425022117.4035031-1-hao.xiang@linux.dev> <20240425022117.4035031-11-hao.xiang@linux.dev> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20240425022117.4035031-11-hao.xiang@linux.dev> Received-SPF: pass client-ip=170.10.129.124; envelope-from=peterx@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -14 X-Spam_score: -1.5 X-Spam_bar: - X-Spam_report: (-1.5 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.897, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_SORBS_WEB=1.5, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=no 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 On Thu, Apr 25, 2024 at 02:21:13AM +0000, Hao Xiang wrote: > Multifd sender path gets an array of pages queued by the migration > thread. It performs zero page checking on every page in the array. > The pages are classfied as either a zero page or a normal page. This > change uses Intel DSA to offload the zero page checking from CPU to > the DSA accelerator. The sender thread submits a batch of pages to DSA > hardware and waits for the DSA completion thread to signal for work > completion. > > Signed-off-by: Hao Xiang > --- > migration/multifd-zero-page.c | 99 +++++++++++++++++++++++++++++++++-- > migration/multifd.c | 27 +++++++++- > migration/multifd.h | 1 + > 3 files changed, 120 insertions(+), 7 deletions(-) > > diff --git a/migration/multifd-zero-page.c b/migration/multifd-zero-page.c > index e1b8370f88..4f426289e4 100644 > --- a/migration/multifd-zero-page.c > +++ b/migration/multifd-zero-page.c > @@ -37,25 +37,83 @@ static void swap_page_offset(ram_addr_t *pages_offset, int a, int b) > } > > /** > - * multifd_send_zero_page_detect: Perform zero page detection on all pages. > + * zero_page_detect_cpu: Perform zero page detection using CPU. > * > * Sorts normal pages before zero pages in p->pages->offset and updates > * p->pages->normal_num. > * > * @param p A pointer to the send params. > */ > -void multifd_send_zero_page_detect(MultiFDSendParams *p) > +static void zero_page_detect_cpu(MultiFDSendParams *p) > { > MultiFDPages_t *pages = p->pages; > RAMBlock *rb = pages->block; > int i = 0; > int j = pages->num - 1; > > - if (!multifd_zero_page_enabled()) { > - pages->normal_num = pages->num; > + /* > + * Sort the page offset array by moving all normal pages to > + * the left and all zero pages to the right of the array. > + */ > + while (i <= j) { > + uint64_t offset = pages->offset[i]; > + > + if (!buffer_is_zero(rb->host + offset, p->page_size)) { > + i++; > + continue; > + } > + > + swap_page_offset(pages->offset, i, j); > + ram_release_page(rb->idstr, offset); > + j--; > + } > + > + pages->normal_num = i; > +} > + > + > +#ifdef CONFIG_DSA_OPT > + > +static void swap_result(bool *results, int a, int b) > +{ > + bool temp; > + > + if (a == b) { > return; > } > > + temp = results[a]; > + results[a] = results[b]; > + results[b] = temp; > +} > + > +/** > + * zero_page_detect_dsa: Perform zero page detection using > + * Intel Data Streaming Accelerator (DSA). > + * > + * Sorts normal pages before zero pages in p->pages->offset and updates > + * p->pages->normal_num. > + * > + * @param p A pointer to the send params. > + */ > +static void zero_page_detect_dsa(MultiFDSendParams *p) > +{ > + MultiFDPages_t *pages = p->pages; > + RAMBlock *rb = pages->block; > + bool *results = p->batch_task->results; > + > + for (int i = 0; i < p->pages->num; i++) { > + p->batch_task->addr[i] = (ram_addr_t)(rb->host + p->pages->offset[i]); > + } > + > + buffer_is_zero_dsa_batch_async(p->batch_task, > + (const void **)p->batch_task->addr, > + p->pages->num, > + p->page_size); > + > + int i = 0; > + int j = pages->num - 1; > + > /* > * Sort the page offset array by moving all normal pages to > * the left and all zero pages to the right of the array. > @@ -63,11 +121,12 @@ void multifd_send_zero_page_detect(MultiFDSendParams *p) > while (i <= j) { > uint64_t offset = pages->offset[i]; > > - if (!buffer_is_zero(rb->host + offset, p->page_size)) { > + if (!results[i]) { > i++; > continue; > } > > + swap_result(results, i, j); > swap_page_offset(pages->offset, i, j); > ram_release_page(rb->idstr, offset); > j--; > @@ -76,6 +135,15 @@ void multifd_send_zero_page_detect(MultiFDSendParams *p) > pages->normal_num = i; > } > > +#else > + > +static void zero_page_detect_dsa(MultiFDSendParams *p) > +{ > + exit(1); > +} > + > +#endif > + > void multifd_recv_zero_page_process(MultiFDRecvParams *p) > { > for (int i = 0; i < p->zero_num; i++) { > @@ -87,3 +155,24 @@ void multifd_recv_zero_page_process(MultiFDRecvParams *p) > } > } > } > + > +/** > + * multifd_send_zero_page_detect: Perform zero page detection on all pages. > + * > + * @param p A pointer to the send params. > + */ > +void multifd_send_zero_page_detect(MultiFDSendParams *p) > +{ > + MultiFDPages_t *pages = p->pages; > + > + if (!multifd_zero_page_enabled()) { > + pages->normal_num = pages->num; > + return; > + } > + > + if (dsa_is_running()) { > + zero_page_detect_dsa(p); > + } else { > + zero_page_detect_cpu(p); > + } > +} > diff --git a/migration/multifd.c b/migration/multifd.c > index cfd3a92f6c..7316643d0a 100644 > --- a/migration/multifd.c > +++ b/migration/multifd.c > @@ -818,6 +818,8 @@ void multifd_send_shutdown(void) > > multifd_send_terminate_threads(); > > + dsa_cleanup(); > + > for (i = 0; i < migrate_multifd_channels(); i++) { > MultiFDSendParams *p = &multifd_send_state->params[i]; > Error *local_err = NULL; > @@ -1155,11 +1157,20 @@ bool multifd_send_setup(void) > uint32_t page_count = MULTIFD_PACKET_SIZE / qemu_target_page_size(); > bool use_packets = multifd_use_packets(); > uint8_t i; > + const char *dsa_parameter = migrate_multifd_dsa_accel(); > > if (!migrate_multifd()) { > return true; > } > > + if (dsa_init(dsa_parameter)) { > + error_setg(&local_err, "multifd: Sender failed to initialize DSA."); > + error_report_err(local_err); > + return false; > + } > + > + dsa_start(); Commented on this in another reply, let's condense them into a single dsa call. That call should also be nested into a flag to know at least dsa is enabled: if (multifd_dsa_enabled()) { multifd_dsa_init(); } Multifd used to have some legacy code where it randomly call multifd_* functions directly in generic migration code. Not a good example to follow there.. Also, I'd think it better if we don't introduce global vars for dsa, it should be put under multifd_send_state (or recv_state). So anything like dsa_start() should always take that pointer first. > + > thread_count = migrate_multifd_channels(); > multifd_send_state = g_malloc0(sizeof(*multifd_send_state)); > multifd_send_state->params = g_new0(MultiFDSendParams, thread_count); > @@ -1393,6 +1404,7 @@ void multifd_recv_cleanup(void) > qemu_thread_join(&p->thread); > } > } > + dsa_cleanup(); Same here. > for (i = 0; i < migrate_multifd_channels(); i++) { > multifd_recv_cleanup_channel(&multifd_recv_state->params[i]); > } > @@ -1568,6 +1580,9 @@ int multifd_recv_setup(Error **errp) > uint32_t page_count = MULTIFD_PACKET_SIZE / qemu_target_page_size(); > bool use_packets = multifd_use_packets(); > uint8_t i; > + const char *dsa_parameter = migrate_multifd_dsa_accel(); > + int ret; > + Error *local_err = NULL; > > /* > * Return successfully if multiFD recv state is already initialised > @@ -1577,6 +1592,15 @@ int multifd_recv_setup(Error **errp) > return 0; > } > > + ret = dsa_init(dsa_parameter); > + if (ret != 0) { > + error_setg(&local_err, "multifd: Receiver failed to initialize DSA."); > + error_propagate(errp, local_err); > + return ret; > + } > + > + dsa_start(); Same here. in the dsa case, it'll be even better if you can find a way to unify send/recv, as IIUC they do work similarly, setup() some dsa stuff, do some zero page detection, cleanup() some dsa stuff. They look all the same irrelevant of src/dst. I think it's nice if we can merge them. > + > thread_count = migrate_multifd_channels(); > multifd_recv_state = g_malloc0(sizeof(*multifd_recv_state)); > multifd_recv_state->params = g_new0(MultiFDRecvParams, thread_count); > @@ -1616,13 +1640,12 @@ int multifd_recv_setup(Error **errp) > > for (i = 0; i < thread_count; i++) { > MultiFDRecvParams *p = &multifd_recv_state->params[i]; > - int ret; > - > ret = multifd_recv_state->ops->recv_setup(p, errp); > if (ret) { > return ret; > } > } > + > return 0; > } > > diff --git a/migration/multifd.h b/migration/multifd.h > index 16e27db5e9..b3717fae24 100644 > --- a/migration/multifd.h > +++ b/migration/multifd.h > @@ -14,6 +14,7 @@ > #define QEMU_MIGRATION_MULTIFD_H > > #include "ram.h" > +#include "qemu/dsa.h" > > typedef struct MultiFDRecvData MultiFDRecvData; > > -- > 2.30.2 > > -- Peter Xu