From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:51212) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TiPFb-000708-6o for qemu-devel@nongnu.org; Tue, 11 Dec 2012 07:48:04 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1TiPFU-0004Vl-LO for qemu-devel@nongnu.org; Tue, 11 Dec 2012 07:47:55 -0500 Received: from mx1.redhat.com ([209.132.183.28]:41351) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TiPFU-0004Va-F4 for qemu-devel@nongnu.org; Tue, 11 Dec 2012 07:47:48 -0500 Received: from int-mx01.intmail.prod.int.phx2.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id qBBCll0V004693 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK) for ; Tue, 11 Dec 2012 07:47:47 -0500 From: Juan Quintela Date: Tue, 11 Dec 2012 13:47:05 +0100 Message-Id: <1355230031-28233-30-git-send-email-quintela@redhat.com> In-Reply-To: <1355230031-28233-1-git-send-email-quintela@redhat.com> References: <1355230031-28233-1-git-send-email-quintela@redhat.com> Subject: [Qemu-devel] [PATCH 29/35] ram: optimize migration bitmap walking List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Instead of testing each page individually, we search what is the next dirty page with a bitmap operation. We have to reorganize the code to move from a "for" loop, to a while(dirty) loop. Signed-off-by: Juan Quintela --- arch_init.c | 45 ++++++++++++++++++++++++++------------------- 1 file changed, 26 insertions(+), 19 deletions(-) diff --git a/arch_init.c b/arch_init.c index b204602..6c12a7d 100644 --- a/arch_init.c +++ b/arch_init.c @@ -343,18 +343,21 @@ static unsigned long *migration_bitmap; static uint64_t migration_dirty_pages; static uint32_t last_version; -static inline bool migration_bitmap_test_and_reset_dirty(MemoryRegion *mr, - ram_addr_t offset) +static inline +ram_addr_t migration_bitmap_find_and_reset_dirty(MemoryRegion *mr, + ram_addr_t start) { - bool ret; - int nr = (mr->ram_addr + offset) >> TARGET_PAGE_BITS; + unsigned long base = mr->ram_addr >> TARGET_PAGE_BITS; + unsigned long nr = base + (start >> TARGET_PAGE_BITS); + unsigned long size = base + (int128_get64(mr->size) >> TARGET_PAGE_BITS); - ret = test_and_clear_bit(nr, migration_bitmap); + unsigned long next = find_next_bit(migration_bitmap, size, nr); - if (ret) { + if (next < size) { + clear_bit(next, migration_bitmap); migration_dirty_pages--; } - return ret; + return (next - base) << TARGET_PAGE_BITS; } static inline bool migration_bitmap_set_dirty(MemoryRegion *mr, @@ -423,6 +426,7 @@ static int ram_save_block(QEMUFile *f, bool last_stage) { RAMBlock *block = last_seen_block; ram_addr_t offset = last_offset; + bool complete_round = false; int bytes_sent = -1; MemoryRegion *mr; ram_addr_t current_addr; @@ -430,9 +434,21 @@ static int ram_save_block(QEMUFile *f, bool last_stage) if (!block) block = QLIST_FIRST(&ram_list.blocks); - do { + while(true) { mr = block->mr; - if (migration_bitmap_test_and_reset_dirty(mr, offset)) { + offset = migration_bitmap_find_and_reset_dirty(mr, offset); + if (complete_round && block == last_seen_block && + offset >= last_offset) { + break; + } + if (offset >= block->length) { + offset = 0; + block = QLIST_NEXT(block, next); + if (!block) { + block = QLIST_FIRST(&ram_list.blocks); + complete_round = true; + } + } else { uint8_t *p; int cont = (block == last_sent_block) ? RAM_SAVE_FLAG_CONTINUE : 0; @@ -467,16 +483,7 @@ static int ram_save_block(QEMUFile *f, bool last_stage) break; } } - - offset += TARGET_PAGE_SIZE; - if (offset >= block->length) { - offset = 0; - block = QLIST_NEXT(block, next); - if (!block) - block = QLIST_FIRST(&ram_list.blocks); - } - } while (block != last_seen_block || offset != last_offset); - + } last_seen_block = block; last_offset = offset; -- 1.7.11.7