From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:32976) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Tv9gy-00025P-Vk for qemu-devel@nongnu.org; Tue, 15 Jan 2013 11:48:55 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Tv9gw-0005Wx-7e for qemu-devel@nongnu.org; Tue, 15 Jan 2013 11:48:52 -0500 Received: from mx1.redhat.com ([209.132.183.28]:8957) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Tv9gw-0005Wc-10 for qemu-devel@nongnu.org; Tue, 15 Jan 2013 11:48:50 -0500 From: Stefan Hajnoczi Date: Tue, 15 Jan 2013 17:48:18 +0100 Message-Id: <1358268511-27061-3-git-send-email-stefanha@redhat.com> In-Reply-To: <1358268511-27061-1-git-send-email-stefanha@redhat.com> References: <1358268511-27061-1-git-send-email-stefanha@redhat.com> Subject: [Qemu-devel] [PATCH 02/15] 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: Peter Lieven , Anthony Liguori , Peter Lieven , Stefan Hajnoczi From: Peter Lieven 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 Reviewed-by: Paolo Bonzini Signed-off-by: Stefan Hajnoczi --- block.c | 4 ---- 1 file changed, 4 deletions(-) diff --git a/block.c b/block.c index b5e64ec..4a90dd1 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; } -- 1.8.0.2