From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:50085) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ek7CT-0006FZ-NV for qemu-devel@nongnu.org; Fri, 09 Feb 2018 06:50:42 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ek7CQ-00064u-Jb for qemu-devel@nongnu.org; Fri, 09 Feb 2018 06:50:41 -0500 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:37976 helo=mx1.redhat.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1ek7CQ-00064Y-De for qemu-devel@nongnu.org; Fri, 09 Feb 2018 06:50:38 -0500 Date: Fri, 9 Feb 2018 11:50:21 +0000 From: "Dr. David Alan Gilbert" Message-ID: <20180209115021.GB2428@work-vm> References: <1517915299-15349-1-git-send-email-wei.w.wang@intel.com> <1517915299-15349-3-git-send-email-wei.w.wang@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1517915299-15349-3-git-send-email-wei.w.wang@intel.com> Subject: Re: [Qemu-devel] [PATCH v2 2/3] migration: use the free page reporting feature from balloon List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Wei Wang Cc: qemu-devel@nongnu.org, mst@redhat.com, quintela@redhat.com, pbonzini@redhat.com, liliang.opensource@gmail.com, yang.zhang.wz@gmail.com, quan.xu0@gmail.com, nilal@redhat.com * Wei Wang (wei.w.wang@intel.com) wrote: > Use the free page reporting feature from the balloon device to clear the > bits corresponding to guest free pages from the dirty bitmap, so that the > free memory are not sent. > > Signed-off-by: Wei Wang > CC: Michael S. Tsirkin > CC: Juan Quintela > --- > migration/ram.c | 24 ++++++++++++++++++++---- > 1 file changed, 20 insertions(+), 4 deletions(-) > > diff --git a/migration/ram.c b/migration/ram.c > index d6f462c..4fe16d2 100644 > --- a/migration/ram.c > +++ b/migration/ram.c > @@ -49,6 +49,7 @@ > #include "qemu/rcu_queue.h" > #include "migration/colo.h" > #include "migration/block.h" > +#include "sysemu/balloon.h" > > /***********************************************************/ > /* ram save/restore */ > @@ -206,6 +207,10 @@ struct RAMState { > uint32_t last_version; > /* We are in the first round */ > bool ram_bulk_stage; > + /* The feature, skipping the transfer of free pages, is supported */ > + bool free_page_support; > + /* Skip the transfer of free pages in the bulk stage */ > + bool free_page_done; > /* How many times we have dirty too many pages */ > int dirty_rate_high_cnt; > /* these variables are used for bitmap sync */ > @@ -773,7 +778,7 @@ unsigned long migration_bitmap_find_dirty(RAMState *rs, RAMBlock *rb, > unsigned long *bitmap = rb->bmap; > unsigned long next; > > - if (rs->ram_bulk_stage && start > 0) { > + if (rs->ram_bulk_stage && start > 0 && !rs->free_page_support) { > next = start + 1; > } else { > next = find_next_bit(bitmap, size, start); > @@ -1653,6 +1658,8 @@ static void ram_state_reset(RAMState *rs) > rs->last_page = 0; > rs->last_version = ram_list.version; > rs->ram_bulk_stage = true; > + rs->free_page_support = balloon_free_page_support(); > + rs->free_page_done = false; > } > > #define MAX_WAIT 50 /* ms, half buffered_file limit */ > @@ -2135,7 +2142,7 @@ static int ram_state_init(RAMState **rsp) > return 0; > } > > -static void ram_list_init_bitmaps(void) > +static void ram_list_init_bitmaps(RAMState *rs) > { > RAMBlock *block; > unsigned long pages; > @@ -2145,7 +2152,11 @@ static void ram_list_init_bitmaps(void) > QLIST_FOREACH_RCU(block, &ram_list.blocks, next) { > pages = block->max_length >> TARGET_PAGE_BITS; > block->bmap = bitmap_new(pages); > - bitmap_set(block->bmap, 0, pages); > + if (rs->free_page_support) { > + bitmap_set(block->bmap, 1, pages); I don't understand how it makes sense to do that here; ignoring anything ese it means that migration_dirty_pages is wrong which could end up with migration finishing before all real pages are sent. Dave > + } else { > + bitmap_set(block->bmap, 0, pages); > + } > if (migrate_postcopy_ram()) { > block->unsentmap = bitmap_new(pages); > bitmap_set(block->unsentmap, 0, pages); > @@ -2161,7 +2172,7 @@ static void ram_init_bitmaps(RAMState *rs) > qemu_mutex_lock_ramlist(); > rcu_read_lock(); > > - ram_list_init_bitmaps(); > + ram_list_init_bitmaps(rs); > memory_global_dirty_log_start(); > migration_bitmap_sync(rs); > > @@ -2275,6 +2286,11 @@ static int ram_save_iterate(QEMUFile *f, void *opaque) > > ram_control_before_iterate(f, RAM_CONTROL_ROUND); > > + if (rs->free_page_support && !rs->free_page_done) { > + balloon_free_page_poll(); > + rs->free_page_done = true; > + } > + > t0 = qemu_clock_get_ns(QEMU_CLOCK_REALTIME); > i = 0; > while ((ret = qemu_file_rate_limit(f)) == 0) { > -- > 1.8.3.1 > -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK