From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:36957) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1a3rBm-0003e1-1L for qemu-devel@nongnu.org; Tue, 01 Dec 2015 15:06:15 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1a3rBg-0008Mi-Gp for qemu-devel@nongnu.org; Tue, 01 Dec 2015 15:06:13 -0500 Received: from mx1.redhat.com ([209.132.183.28]:49066) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1a3rBg-0008MX-9Y for qemu-devel@nongnu.org; Tue, 01 Dec 2015 15:06:08 -0500 Date: Tue, 1 Dec 2015 20:06:00 +0000 From: "Dr. David Alan Gilbert" Message-ID: <20151201200600.GF31209@work-vm> References: <1448357149-17572-1-git-send-email-zhang.zhanghailiang@huawei.com> <1448357149-17572-19-git-send-email-zhang.zhanghailiang@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1448357149-17572-19-git-send-email-zhang.zhanghailiang@huawei.com> Subject: Re: [Qemu-devel] [PATCH COLO-Frame v11 18/39] COLO: Flush PVM's cached RAM into SVM's memory List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: zhanghailiang Cc: lizhijian@cn.fujitsu.com, quintela@redhat.com, yunhong.jiang@intel.com, eddie.dong@intel.com, peter.huangpeng@huawei.com, qemu-devel@nongnu.org, arei.gonglei@huawei.com, stefanha@redhat.com, amit.shah@redhat.com, hongyang.yang@easystack.cn * zhanghailiang (zhang.zhanghailiang@huawei.com) wrote: > During the time of VM's running, PVM may dirty some pages, we will transfer > PVM's dirty pages to SVM and store them into SVM's RAM cache at next checkpoint > time. So, the content of SVM's RAM cache will always be some with PVM's memory > after checkpoint. > > Instead of flushing all content of PVM's RAM cache into SVM's MEMORY, > we do this in a more efficient way: > Only flush any page that dirtied by PVM since last checkpoint. > In this way, we can ensure SVM's memory same with PVM's. > > Besides, we must ensure flush RAM cache before load device state. > > Signed-off-by: zhanghailiang > Signed-off-by: Li Zhijian > Signed-off-by: Gonglei > --- > v11: > - Move the place of 'need_flush' (Dave's suggestion) > - Remove unused 'DPRINTF("Flush ram_cache\n")' > v10: > - trace the number of dirty pages that be received. > --- > include/migration/migration.h | 1 + > migration/colo.c | 2 -- > migration/ram.c | 37 +++++++++++++++++++++++++++++++++++++ > trace-events | 1 + > 4 files changed, 39 insertions(+), 2 deletions(-) > > diff --git a/include/migration/migration.h b/include/migration/migration.h > index e41372d..221176b 100644 > --- a/include/migration/migration.h > +++ b/include/migration/migration.h > @@ -336,4 +336,5 @@ PostcopyState postcopy_state_set(PostcopyState new_state); > /* ram cache */ > int colo_init_ram_cache(void); > void colo_release_ram_cache(void); > +void colo_flush_ram_cache(void); > #endif > diff --git a/migration/colo.c b/migration/colo.c > index 5ac8ff2..4095d97 100644 > --- a/migration/colo.c > +++ b/migration/colo.c > @@ -385,8 +385,6 @@ void *colo_process_incoming_thread(void *opaque) > } > qemu_mutex_unlock_iothread(); > > - /* TODO: flush vm state */ > - Might have been better to put the TODO in a place that needed to be changed! > ret = colo_ctl_put(mis->to_src_file, COLO_COMMAND_VMSTATE_LOADED, 0); > if (ret < 0) { > goto out; > diff --git a/migration/ram.c b/migration/ram.c > index da6bbd6..4f37144 100644 > --- a/migration/ram.c > +++ b/migration/ram.c > @@ -2448,6 +2448,7 @@ static int ram_load(QEMUFile *f, void *opaque, int version_id) > * be atomic > */ > bool postcopy_running = postcopy_state_get() >= POSTCOPY_INCOMING_LISTENING; > + bool need_flush = false; > > seq_iter++; > > @@ -2482,6 +2483,7 @@ static int ram_load(QEMUFile *f, void *opaque, int version_id) > /* After going into COLO, we should load the Page into colo_cache */ > if (ram_cache_enable) { > host = colo_cache_from_block_offset(block, addr); > + need_flush = true; > } else { > host = host_from_ram_block_offset(block, addr); > } > @@ -2575,6 +2577,10 @@ static int ram_load(QEMUFile *f, void *opaque, int version_id) > } > > rcu_read_unlock(); > + > + if (!ret && ram_cache_enable && need_flush) { > + colo_flush_ram_cache(); > + } > DPRINTF("Completed load of VM with exit code %d seq iteration " > "%" PRIu64 "\n", ret, seq_iter); > return ret; > @@ -2647,6 +2653,37 @@ void colo_release_ram_cache(void) > rcu_read_unlock(); > } > > +/* > + * Flush content of RAM cache into SVM's memory. > + * Only flush the pages that be dirtied by PVM or SVM or both. > + */ > +void colo_flush_ram_cache(void) > +{ > + RAMBlock *block = NULL; > + void *dst_host; > + void *src_host; > + ram_addr_t offset = 0; > + > + trace_colo_flush_ram_cache(migration_dirty_pages); > + rcu_read_lock(); > + block = QLIST_FIRST_RCU(&ram_list.blocks); > + while (block) { > + ram_addr_t ram_addr_abs; > + offset = migration_bitmap_find_dirty(block, offset, &ram_addr_abs); > + migration_bitmap_clear_dirty(ram_addr_abs); > + if (offset >= block->used_length) { > + offset = 0; > + block = QLIST_NEXT_RCU(block, next); > + } else { > + dst_host = block->host + offset; > + src_host = block->colo_cache + offset; > + memcpy(dst_host, src_host, TARGET_PAGE_SIZE); > + } > + } > + rcu_read_unlock(); If you added a trace point here as well, it would make it very easy to measure how long the flush was taking. > + assert(migration_dirty_pages == 0); > +} > + > static SaveVMHandlers savevm_ram_handlers = { > .save_live_setup = ram_save_setup, > .save_live_iterate = ram_save_iterate, > diff --git a/trace-events b/trace-events > index f8a0959..f158d2a 100644 > --- a/trace-events > +++ b/trace-events > @@ -1264,6 +1264,7 @@ migration_throttle(void) "" > ram_load_postcopy_loop(uint64_t addr, int flags) "@%" PRIx64 " %x" > ram_postcopy_send_discard_bitmap(void) "" > ram_save_queue_pages(const char *rbname, size_t start, size_t len) "%s: start: %zx len: %zx" > +colo_flush_ram_cache(uint64_t dirty_pages) "dirty_pages %" PRIu64"" Minor; I think you can remove the "" at the end. Other than those minor things (and those double-space!): Reviewed-by: Dr. David Alan Gilbert Dave > > # hw/display/qxl.c > disable qxl_interface_set_mm_time(int qid, uint32_t mm_time) "%d %d" > -- > 1.8.3.1 > > -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK