From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:48240) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1d2ik4-0006QX-Ee for qemu-devel@nongnu.org; Mon, 24 Apr 2017 14:29:45 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1d2ik1-0002MC-Bi for qemu-devel@nongnu.org; Mon, 24 Apr 2017 14:29:44 -0400 Received: from mx1.redhat.com ([209.132.183.28]:34864) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1d2ik1-0002Lj-1v for qemu-devel@nongnu.org; Mon, 24 Apr 2017 14:29:41 -0400 From: Juan Quintela In-Reply-To: <1492850128-17472-9-git-send-email-zhang.zhanghailiang@huawei.com> (zhanghailiang's message of "Sat, 22 Apr 2017 16:35:18 +0800") References: <1492850128-17472-1-git-send-email-zhang.zhanghailiang@huawei.com> <1492850128-17472-9-git-send-email-zhang.zhanghailiang@huawei.com> Reply-To: quintela@redhat.com Date: Mon, 24 Apr 2017 20:29:38 +0200 Message-ID: <87lgqpoe0d.fsf@secure.mitica> MIME-Version: 1.0 Content-Type: text/plain Subject: Re: [Qemu-devel] [PATCH RESEND v2 08/18] ram/COLO: Record the dirty pages that SVM received List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: zhanghailiang Cc: qemu-devel@nongnu.org, dgilbert@redhat.com, zhangchen.fnst@cn.fujitsu.com zhanghailiang wrote: > We record the address of the dirty pages that received, > it will help flushing pages that cached into SVM. > > Here, it is a trick, we record dirty pages by re-using migration > dirty bitmap. In the later patch, we will start the dirty log > for SVM, just like migration, in this way, we can record both > the dirty pages caused by PVM and SVM, we only flush those dirty > pages from RAM cache while do checkpoint. > > Cc: Juan Quintela > Signed-off-by: zhanghailiang > Reviewed-by: Dr. David Alan Gilbert > --- > migration/ram.c | 29 +++++++++++++++++++++++++++++ > 1 file changed, 29 insertions(+) > > diff --git a/migration/ram.c b/migration/ram.c > index 05d1b06..0653a24 100644 > --- a/migration/ram.c > +++ b/migration/ram.c > @@ -2268,6 +2268,9 @@ static inline void *host_from_ram_block_offset(RAMBlock *block, > static inline void *colo_cache_from_block_offset(RAMBlock *block, > ram_addr_t offset) > { > + unsigned long *bitmap; > + long k; > + > if (!offset_in_ramblock(block, offset)) { > return NULL; > } > @@ -2276,6 +2279,17 @@ static inline void *colo_cache_from_block_offset(RAMBlock *block, > __func__, block->idstr); > return NULL; > } > + > + k = (memory_region_get_ram_addr(block->mr) + offset) >> TARGET_PAGE_BITS; > + bitmap = atomic_rcu_read(&ram_state.ram_bitmap)->bmap; > + /* > + * During colo checkpoint, we need bitmap of these migrated pages. > + * It help us to decide which pages in ram cache should be flushed > + * into VM's RAM later. > + */ > + if (!test_and_set_bit(k, bitmap)) { > + ram_state.migration_dirty_pages++; > + } > return block->colo_cache + offset; > } > > @@ -2752,6 +2766,15 @@ int colo_init_ram_cache(void) > memcpy(block->colo_cache, block->host, block->used_length); > } > rcu_read_unlock(); > + /* > + * Record the dirty pages that sent by PVM, we use this dirty bitmap together > + * with to decide which page in cache should be flushed into SVM's RAM. Here > + * we use the same name 'ram_bitmap' as for migration. > + */ > + ram_state.ram_bitmap = g_new0(RAMBitmap, 1); > + ram_state.ram_bitmap->bmap = bitmap_new(last_ram_page()); > + ram_state.migration_dirty_pages = 0; > + > return 0; > > out_locked: > @@ -2770,6 +2793,12 @@ out_locked: > void colo_release_ram_cache(void) > { > RAMBlock *block; > + RAMBitmap *bitmap = ram_state.ram_bitmap; > + > + atomic_rcu_set(&ram_state.ram_bitmap, NULL); > + if (bitmap) { > + call_rcu(bitmap, migration_bitmap_free, rcu); > + } > > rcu_read_lock(); > QLIST_FOREACH_RCU(block, &ram_list.blocks, next) { You can see my Split bitmap patches, I am splitting the dirty bitmap per block, I think that it shouldn't make your life more difficult, but please take a look. I am wondering if it is faster/easier to use the page_cache.c that xbzrle uses to store the dirty pages instead of copying the whole RAMBlocks, but I don't really know. Thanks, Juan.