From patchwork Mon Feb 8 11:23:37 2010 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: OHMURA Kei X-Patchwork-Id: 44775 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from lists.gnu.org (lists.gnu.org [199.232.76.165]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTPS id 14A03B7D0A for ; Mon, 8 Feb 2010 22:34:35 +1100 (EST) Received: from localhost ([127.0.0.1]:39939 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1NeRr9-0007oQ-0Q for incoming@patchwork.ozlabs.org; Mon, 08 Feb 2010 06:32:43 -0500 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1NeRiW-0005jE-Js for qemu-devel@nongnu.org; Mon, 08 Feb 2010 06:23:48 -0500 Received: from [199.232.76.173] (port=38669 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1NeRiW-0005it-2Y for qemu-devel@nongnu.org; Mon, 08 Feb 2010 06:23:48 -0500 Received: from Debian-exim by monty-python.gnu.org with spam-scanned (Exim 4.60) (envelope-from ) id 1NeRiO-0002pX-8j for qemu-devel@nongnu.org; Mon, 08 Feb 2010 06:23:48 -0500 Received: from tama50.ecl.ntt.co.jp ([129.60.39.147]:39508) by monty-python.gnu.org with esmtp (Exim 4.60) (envelope-from ) id 1NeRiN-0002pJ-JW for qemu-devel@nongnu.org; Mon, 08 Feb 2010 06:23:40 -0500 Received: from mfs5.rdh.ecl.ntt.co.jp (mfs5.rdh.ecl.ntt.co.jp [129.60.39.144]) by tama50.ecl.ntt.co.jp (8.14.3/8.14.3) with ESMTP id o18BNbbd026342; Mon, 8 Feb 2010 20:23:37 +0900 (JST) Received: from mfs5.rdh.ecl.ntt.co.jp (localhost [127.0.0.1]) by mfs5.rdh.ecl.ntt.co.jp (Postfix) with ESMTP id CFABF6CDD; Mon, 8 Feb 2010 20:23:37 +0900 (JST) Received: from dmailsv1.y.ecl.ntt.co.jp (dmailsv1.y.ecl.ntt.co.jp [129.60.53.14]) by mfs5.rdh.ecl.ntt.co.jp (Postfix) with ESMTP id 8375F6CDC; Mon, 8 Feb 2010 20:23:37 +0900 (JST) Received: from mailsv02.y.ecl.ntt.co.jp by dmailsv1.y.ecl.ntt.co.jp (8.14.3/dmailsv1-2.1) with ESMTP id o18BNbhI007007; Mon, 8 Feb 2010 20:23:37 +0900 (JST) Received: from localhost by mailsv02.y.ecl.ntt.co.jp (8.14.3/Lab-1.7) with ESMTP id o18BNbo0009019; Mon, 8 Feb 2010 20:23:37 +0900 (JST) Message-ID: <4B6FF439.6030006@lab.ntt.co.jp> Date: Mon, 08 Feb 2010 20:23:37 +0900 From: OHMURA Kei User-Agent: Thunderbird 2.0.0.23 (Windows/20090812) MIME-Version: 1.0 To: Jan Kiszka , kvm@vger.kernel.org, qemu-devel@nongnu.org References: <4B6BF06D.1090909@lab.ntt.co.jp> <4B6C0958.50704@siemens.com> <4B6FABCE.207@lab.ntt.co.jp> In-Reply-To: <4B6FABCE.207@lab.ntt.co.jp> X-detected-operating-system: by monty-python.gnu.org: Solaris 10 (beta) Cc: ohmura.kei@lab.ntt.co.jp, avi@redhat.com Subject: [Qemu-devel] Re: [PATCH] qemu-kvm: Speed up of the dirty-bitmap-traveling X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org >> Would be great if you could provide a version for upstream as well >> because it will likely replace this qemu-kvm code on day. > O.K. We'll prepare it. We have implemented the version for upstream. Some source code are borrowed from qemu-kvm.c. It is not fully tested yet, though. We also did performance test against this patch. Test environment is the same as the email I sent before. Experimental results: Test1: Guest OS read 3GB file, which is bigger than memory. #called orig.(msec) patch(msec) ratio 14 3.79 0.18 20.8 12 3.20 0.15 21.4 11 2.89 0.14 21.0 Test2: Guest OS read/write 3GB file, which is bigger than memory. #called orig.(msec) patch(msec) ratio 364 180 8.70 20.7 326 161 7.71 20.9 474 235 11.7 20.1 --- kvm-all.c | 80 +++++++++++++++++++++++++++++++++++++++++++++++++----------- 1 files changed, 65 insertions(+), 15 deletions(-) diff --git a/kvm-all.c b/kvm-all.c index 15ec38e..9666843 100644 --- a/kvm-all.c +++ b/kvm-all.c @@ -279,9 +279,69 @@ int kvm_set_migration_log(int enable) return 0; } -static int test_le_bit(unsigned long nr, unsigned char *addr) +static inline void kvm_get_dirty_pages_log_range_by_byte(unsigned int start, + unsigned int end, + unsigned char *bitmap, + unsigned long offset) { - return (addr[nr >> 3] >> (nr & 7)) & 1; + unsigned int i, j, n = 0; + unsigned long page_number, addr, addr1; + ram_addr_t ram_addr; + unsigned char c; + + /* + * bitmap-traveling is faster than memory-traveling (for addr...) + * especially when most of the memory is not dirty. + */ + for (i = start; i < end; i++) { + c = bitmap[i]; + while (c > 0) { + j = ffsl(c) - 1; + c &= ~(1u << j); + page_number = i * 8 + j; + addr1 = page_number * TARGET_PAGE_SIZE; + addr = offset + addr1; + ram_addr = cpu_get_physical_page_desc(addr); + cpu_physical_memory_set_dirty(ram_addr); + n++; + } + } +} + +static int kvm_get_dirty_pages_log_range_by_long(unsigned long start_addr, + unsigned char *bitmap, + unsigned long mem_size) +{ + unsigned int i; + unsigned int len; + unsigned long *bitmap_ul = (unsigned long *)bitmap; + + /* bitmap-traveling by long size is faster than by byte size + * especially when most of memory is not dirty. + * bitmap should be long-size aligned for traveling by long. + */ + if (((unsigned long)bitmap & (TARGET_LONG_SIZE - 1)) == 0) { + len = ((mem_size / TARGET_PAGE_SIZE) + TARGET_LONG_BITS - 1) / + TARGET_LONG_BITS; + for (i = 0; i < len; i++) + if (bitmap_ul[i] != 0) + kvm_get_dirty_pages_log_range_by_byte(i * TARGET_LONG_SIZE, + (i + 1) * TARGET_LONG_SIZE, bitmap, start_addr); + /* + * We will check the remaining dirty-bitmap, + * when the mem_size is not a multiple of TARGET_LONG_SIZE. + */ + if ((mem_size & (TARGET_LONG_SIZE - 1)) != 0) { + len = ((mem_size / TARGET_PAGE_SIZE) + 7) / 8; + kvm_get_dirty_pages_log_range_by_byte(i * TARGET_LONG_SIZE, + len, bitmap, start_addr); + } + } else { /* slow path: traveling by byte. */ + len = ((mem_size / TARGET_PAGE_SIZE) + 7) / 8; + kvm_get_dirty_pages_log_range_by_byte(0, len, bitmap, start_addr); + } + + return 0; } /** @@ -297,8 +357,6 @@ int kvm_physical_sync_dirty_bitmap(target_phys_addr_t start_addr, { KVMState *s = kvm_state; unsigned long size, allocated_size = 0; - target_phys_addr_t phys_addr; - ram_addr_t addr; KVMDirtyLog d; KVMSlot *mem; int ret = 0; @@ -327,17 +385,9 @@ int kvm_physical_sync_dirty_bitmap(target_phys_addr_t start_addr, break; } - for (phys_addr = mem->start_addr, addr = mem->phys_offset; - phys_addr < mem->start_addr + mem->memory_size; - phys_addr += TARGET_PAGE_SIZE, addr += TARGET_PAGE_SIZE) { - unsigned char *bitmap = (unsigned char *)d.dirty_bitmap; - unsigned nr = (phys_addr - mem->start_addr) >> TARGET_PAGE_BITS; - - if (test_le_bit(nr, bitmap)) { - cpu_physical_memory_set_dirty(addr); - } - } - start_addr = phys_addr; + kvm_get_dirty_pages_log_range_by_long(mem->start_addr, + d.dirty_bitmap, mem->memory_size); + start_addr = mem->start_addr + mem->memory_size; } qemu_free(d.dirty_bitmap);