From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:51957) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cwXKv-0006sa-Si for qemu-devel@nongnu.org; Fri, 07 Apr 2017 13:06:15 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1cwXKr-0006Mh-Rq for qemu-devel@nongnu.org; Fri, 07 Apr 2017 13:06:13 -0400 Received: from mx1.redhat.com ([209.132.183.28]:44578) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1cwXKr-0006M4-Iw for qemu-devel@nongnu.org; Fri, 07 Apr 2017 13:06:09 -0400 Date: Fri, 7 Apr 2017 18:06:04 +0100 From: "Dr. David Alan Gilbert" Message-ID: <20170407170600.GD2623@work-vm> References: <1487734936-43472-1-git-send-email-zhang.zhanghailiang@huawei.com> <1487734936-43472-8-git-send-email-zhang.zhanghailiang@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1487734936-43472-8-git-send-email-zhang.zhanghailiang@huawei.com> Subject: Re: [Qemu-devel] [PATCH 07/15] COLO: Load PVM's dirty pages into SVM's RAM cache temporarily List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: zhanghailiang Cc: qemu-devel@nongnu.org, zhangchen.fnst@cn.fujitsu.com, lizhijian@cn.fujitsu.com, xiecl.fnst@cn.fujitsu.com, Juan Quintela * zhanghailiang (zhang.zhanghailiang@huawei.com) wrote: > We should not load PVM's state directly into SVM, because there maybe some > errors happen when SVM is receving data, which will break SVM. > > We need to ensure receving all data before load the state into SVM. We use > an extra memory to cache these data (PVM's ram). The ram cache in secondary side > is initially the same as SVM/PVM's memory. And in the process of checkpoint, > we cache the dirty pages of PVM into this ram cache firstly, so this ram cache > always the same as PVM's memory at every checkpoint, then we flush this cached ram > to SVM after we receive all PVM's state. You're probably going to find this interesting to merge with Juan's recent RAM block series. Probably not too hard, but he's touching a lot of the same code and rearranging things. Dave > Cc: Juan Quintela > Signed-off-by: zhanghailiang > Signed-off-by: Li Zhijian > Reviewed-by: Dr. David Alan Gilbert > --- > include/exec/ram_addr.h | 1 + > include/migration/migration.h | 4 +++ > migration/colo.c | 14 +++++++++ > migration/ram.c | 73 ++++++++++++++++++++++++++++++++++++++++++- > 4 files changed, 91 insertions(+), 1 deletion(-) > > diff --git a/include/exec/ram_addr.h b/include/exec/ram_addr.h > index 3e79466..44e1190 100644 > --- a/include/exec/ram_addr.h > +++ b/include/exec/ram_addr.h > @@ -27,6 +27,7 @@ struct RAMBlock { > struct rcu_head rcu; > struct MemoryRegion *mr; > uint8_t *host; > + uint8_t *colo_cache; /* For colo, VM's ram cache */ > ram_addr_t offset; > ram_addr_t used_length; > ram_addr_t max_length; > diff --git a/include/migration/migration.h b/include/migration/migration.h > index 1735d66..93c6148 100644 > --- a/include/migration/migration.h > +++ b/include/migration/migration.h > @@ -379,4 +379,8 @@ int ram_save_queue_pages(MigrationState *ms, const char *rbname, > PostcopyState postcopy_state_get(void); > /* Set the state and return the old state */ > PostcopyState postcopy_state_set(PostcopyState new_state); > + > +/* ram cache */ > +int colo_init_ram_cache(void); > +void colo_release_ram_cache(void); > #endif > diff --git a/migration/colo.c b/migration/colo.c > index 1e3e975..edb7f00 100644 > --- a/migration/colo.c > +++ b/migration/colo.c > @@ -551,6 +551,7 @@ void *colo_process_incoming_thread(void *opaque) > uint64_t total_size; > uint64_t value; > Error *local_err = NULL; > + int ret; > > qemu_sem_init(&mis->colo_incoming_sem, 0); > > @@ -572,6 +573,12 @@ void *colo_process_incoming_thread(void *opaque) > */ > qemu_file_set_blocking(mis->from_src_file, true); > > + ret = colo_init_ram_cache(); > + if (ret < 0) { > + error_report("Failed to initialize ram cache"); > + goto out; > + } > + > bioc = qio_channel_buffer_new(COLO_BUFFER_BASE_SIZE); > fb = qemu_fopen_channel_input(QIO_CHANNEL(bioc)); > object_unref(OBJECT(bioc)); > @@ -705,11 +712,18 @@ out: > if (fb) { > qemu_fclose(fb); > } > + /* > + * We can ensure BH is hold the global lock, and will join COLO > + * incoming thread, so here it is not necessary to lock here again, > + * Or there will be a deadlock error. > + */ > + colo_release_ram_cache(); > > /* Hope this not to be too long to loop here */ > qemu_sem_wait(&mis->colo_incoming_sem); > qemu_sem_destroy(&mis->colo_incoming_sem); > /* Must be called after failover BH is completed */ > + > if (mis->to_src_file) { > qemu_fclose(mis->to_src_file); > } > diff --git a/migration/ram.c b/migration/ram.c > index f289fcd..b588990 100644 > --- a/migration/ram.c > +++ b/migration/ram.c > @@ -219,6 +219,7 @@ static RAMBlock *last_sent_block; > static ram_addr_t last_offset; > static QemuMutex migration_bitmap_mutex; > static uint64_t migration_dirty_pages; > +static bool ram_cache_enable; > static uint32_t last_version; > static bool ram_bulk_stage; > > @@ -2227,6 +2228,20 @@ static inline void *host_from_ram_block_offset(RAMBlock *block, > return block->host + offset; > } > > +static inline void *colo_cache_from_block_offset(RAMBlock *block, > + ram_addr_t offset) > +{ > + if (!offset_in_ramblock(block, offset)) { > + return NULL; > + } > + if (!block->colo_cache) { > + error_report("%s: colo_cache is NULL in block :%s", > + __func__, block->idstr); > + return NULL; > + } > + return block->colo_cache + offset; > +} > + > /* > * If a page (or a whole RDMA chunk) has been > * determined to be zero, then zap it. > @@ -2542,7 +2557,12 @@ static int ram_load(QEMUFile *f, void *opaque, int version_id) > RAM_SAVE_FLAG_COMPRESS_PAGE | RAM_SAVE_FLAG_XBZRLE)) { > RAMBlock *block = ram_block_from_stream(f, flags); > > - host = host_from_ram_block_offset(block, addr); > + /* After going into COLO, we should load the Page into colo_cache */ > + if (ram_cache_enable) { > + host = colo_cache_from_block_offset(block, addr); > + } else { > + host = host_from_ram_block_offset(block, addr); > + } > if (!host) { > error_report("Illegal RAM offset " RAM_ADDR_FMT, addr); > ret = -EINVAL; > @@ -2637,6 +2657,57 @@ static int ram_load(QEMUFile *f, void *opaque, int version_id) > return ret; > } > > +/* > + * colo cache: this is for secondary VM, we cache the whole > + * memory of the secondary VM, it will be called after first migration. > + */ > +int colo_init_ram_cache(void) > +{ > + RAMBlock *block; > + > + rcu_read_lock(); > + QLIST_FOREACH_RCU(block, &ram_list.blocks, next) { > + block->colo_cache = qemu_anon_ram_alloc(block->used_length, NULL); > + if (!block->colo_cache) { > + error_report("%s: Can't alloc memory for COLO cache of block %s," > + "size 0x" RAM_ADDR_FMT, __func__, block->idstr, > + block->used_length); > + goto out_locked; > + } > + memcpy(block->colo_cache, block->host, block->used_length); > + } > + rcu_read_unlock(); > + ram_cache_enable = true; > + return 0; > + > +out_locked: > + QLIST_FOREACH_RCU(block, &ram_list.blocks, next) { > + if (block->colo_cache) { > + qemu_anon_ram_free(block->colo_cache, block->used_length); > + block->colo_cache = NULL; > + } > + } > + > + rcu_read_unlock(); > + return -errno; > +} > + > +void colo_release_ram_cache(void) > +{ > + RAMBlock *block; > + > + ram_cache_enable = false; > + > + rcu_read_lock(); > + QLIST_FOREACH_RCU(block, &ram_list.blocks, next) { > + if (block->colo_cache) { > + qemu_anon_ram_free(block->colo_cache, block->used_length); > + block->colo_cache = NULL; > + } > + } > + rcu_read_unlock(); > +} > + > static SaveVMHandlers savevm_ram_handlers = { > .save_live_setup = ram_save_setup, > .save_live_iterate = ram_save_iterate, > -- > 1.8.3.1 > > -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK