From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:40283) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ettZJ-0004Wi-K6 for qemu-devel@nongnu.org; Thu, 08 Mar 2018 06:18:43 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ettZH-000205-OP for qemu-devel@nongnu.org; Thu, 08 Mar 2018 06:18:41 -0500 Received: from mx-v6.kamp.de ([2a02:248:0:51::16]:37955 helo=mx01.kamp.de) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1ettZH-0001ze-Et for qemu-devel@nongnu.org; Thu, 08 Mar 2018 06:18:39 -0500 Received: from submission.kamp.de ([195.62.97.28]) by kerio.kamp.de with ESMTPS (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256 bits)) for qemu-devel@nongnu.org; Thu, 8 Mar 2018 12:18:28 +0100 From: Peter Lieven Date: Thu, 8 Mar 2018 12:18:27 +0100 Message-Id: <1520507908-16743-5-git-send-email-pl@kamp.de> In-Reply-To: <1520507908-16743-1-git-send-email-pl@kamp.de> References: <1520507908-16743-1-git-send-email-pl@kamp.de> Subject: [Qemu-devel] [PATCH 4/5] migration/block: limit the number of parallel I/O requests List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org, qemu-block@nongnu.org Cc: dgilbert@redhat.com, quintela@redhat.com, famz@redhat.com, stefanha@redhat.com, jjherne@linux.vnet.ibm.com, Peter Lieven the current implementation submits up to 512 I/O requests in parallel which is much to high especially for a background task. This patch adds a maximum limit of 16 I/O requests that can be submitted in parallel to avoid monopolizing the I/O device. Signed-off-by: Peter Lieven --- migration/block.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/migration/block.c b/migration/block.c index 41b95d1..ce939e2 100644 --- a/migration/block.c +++ b/migration/block.c @@ -37,6 +37,7 @@ #define MAX_IS_ALLOCATED_SEARCH (65536 * BDRV_SECTOR_SIZE) #define MAX_IO_BUFFERS 512 +#define MAX_PARALLEL_IO 16 //#define DEBUG_BLK_MIGRATION @@ -775,6 +776,7 @@ static int block_save_iterate(QEMUFile *f, void *opaque) while ((block_mig_state.submitted + block_mig_state.read_done) * BLOCK_SIZE < qemu_file_get_rate_limit(f) && + block_mig_state.submitted < MAX_PARALLEL_IO && (block_mig_state.submitted + block_mig_state.read_done) < MAX_IO_BUFFERS) { blk_mig_unlock(); -- 2.7.4