From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:52694) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TtdkG-0004Me-5v for qemu-devel@nongnu.org; Fri, 11 Jan 2013 07:30:06 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Ttdk8-0001AS-JH for qemu-devel@nongnu.org; Fri, 11 Jan 2013 07:30:00 -0500 Received: from ssl.dlhnet.de ([91.198.192.8]:58802 helo=ssl.dlh.net) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Ttdk8-0001AO-Ce for qemu-devel@nongnu.org; Fri, 11 Jan 2013 07:29:52 -0500 Message-ID: <50F005C3.5010305@dlhnet.de> Date: Fri, 11 Jan 2013 13:29:55 +0100 From: Peter Lieven MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Subject: [Qemu-devel] [PATCH] block: fix initialization in bdrv_io_limits_enable() List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "qemu-devel@nongnu.org" Cc: Paolo Bonzini bdrv_io_limits_enable() starts a new slice, but does not set io_base correctly for that slice. Here is how io_base is used: bytes_base = bs->nr_bytes[is_write] - bs->io_base.bytes[is_write]; bytes_res = (unsigned) nb_sectors * BDRV_SECTOR_SIZE; if (bytes_base + bytes_res <= bytes_limit) { /* no wait */ } else { /* operation needs to be throttled */ } As a result, any I/O operations that are triggered between now and bs->slice_end are incorrectly limited. If 10 MB of data has been written since the VM was started, QEMU thinks that 10 MB of data has been written in this slice. This leads to a I/O lockup in the guest. We fix this by delaying the start of a new slice to the next call of bdrv_exceed_io_limits(). Signed-off-by: Peter Lieven --- block.c | 4 ---- 1 file changed, 4 deletions(-) diff --git a/block.c b/block.c index 4e28c55..a40a389 100644 --- a/block.c +++ b/block.c @@ -155,10 +155,6 @@ void bdrv_io_limits_enable(BlockDriverState *bs) { qemu_co_queue_init(&bs->throttled_reqs); bs->block_timer = qemu_new_timer_ns(vm_clock, bdrv_block_timer, bs); - bs->slice_time = 5 * BLOCK_IO_SLICE_TIME; - bs->slice_start = qemu_get_clock_ns(vm_clock); - bs->slice_end = bs->slice_start + bs->slice_time; - memset(&bs->io_base, 0, sizeof(bs->io_base)); bs->io_limits_enabled = true; } -- 1.7.9.5