From patchwork Wed Mar 4 09:04:11 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Fam Zheng X-Patchwork-Id: 446154 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from lists.gnu.org (lists.gnu.org [IPv6:2001:4830:134:3::11]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id C45181401AA for ; Wed, 4 Mar 2015 20:04:59 +1100 (AEDT) Received: from localhost ([::1]:42767 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YT5Ef-0004vi-Us for incoming@patchwork.ozlabs.org; Wed, 04 Mar 2015 04:04:57 -0500 Received: from eggs.gnu.org ([2001:4830:134:3::10]:36492) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YT5E5-0004lp-QK for qemu-devel@nongnu.org; Wed, 04 Mar 2015 04:04:27 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1YT5E3-0003lx-58 for qemu-devel@nongnu.org; Wed, 04 Mar 2015 04:04:21 -0500 Received: from mx1.redhat.com ([209.132.183.28]:56971) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YT5E2-0003lp-SB for qemu-devel@nongnu.org; Wed, 04 Mar 2015 04:04:19 -0500 Received: from int-mx14.intmail.prod.int.phx2.redhat.com (int-mx14.intmail.prod.int.phx2.redhat.com [10.5.11.27]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id t2494ITH017049 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL) for ; Wed, 4 Mar 2015 04:04:18 -0500 Received: from ad.nay.redhat.com (dhcp-14-137.nay.redhat.com [10.66.14.137]) by int-mx14.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id t2494FaJ008961; Wed, 4 Mar 2015 04:04:17 -0500 From: Fam Zheng To: qemu-devel@nongnu.org Date: Wed, 4 Mar 2015 17:04:11 +0800 Message-Id: <1425459851-16819-1-git-send-email-famz@redhat.com> X-Scanned-By: MIMEDefang 2.68 on 10.5.11.27 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x X-Received-From: 209.132.183.28 Cc: Kevin Wolf , Stefan Hajnoczi Subject: [Qemu-devel] [PATCH] block/null: Latency simulation by adding new option "latency_ns" X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Aio context switch should just work because the requests will be drained, so the scheduled timer(s) on the old context will be freed. Signed-off-by: Fam Zheng --- block/null.c | 34 ++++++++++++++++++++++++++++++++-- 1 file changed, 32 insertions(+), 2 deletions(-) diff --git a/block/null.c b/block/null.c index ec2bd27..af49525 100644 --- a/block/null.c +++ b/block/null.c @@ -12,8 +12,11 @@ #include "block/block_int.h" +#define NULL_OPT_LATENCY "latency_ns" + typedef struct { int64_t length; + int64_t latency_ns; } BDRVNullState; static QemuOptsList runtime_opts = { @@ -30,6 +33,12 @@ static QemuOptsList runtime_opts = { .type = QEMU_OPT_SIZE, .help = "size of the null block", }, + { + .name = NULL_OPT_LATENCY, + .type = QEMU_OPT_NUMBER, + .help = "nanoseconds (approximated) to wait " + "before completing request", + }, { /* end of list */ } }, }; @@ -44,6 +53,8 @@ static int null_file_open(BlockDriverState *bs, QDict *options, int flags, qemu_opts_absorb_qdict(opts, options, &error_abort); s->length = qemu_opt_get_size(opts, BLOCK_OPT_SIZE, 1 << 30); + s->latency_ns = + qemu_opt_get_number(opts, NULL_OPT_LATENCY, 0); qemu_opts_del(opts); return 0; } @@ -80,6 +91,7 @@ static coroutine_fn int null_co_flush(BlockDriverState *bs) typedef struct { BlockAIOCB common; QEMUBH *bh; + QEMUTimer timer; } NullAIOCB; static const AIOCBInfo null_aiocb_info = { @@ -94,15 +106,33 @@ static void null_bh_cb(void *opaque) qemu_aio_unref(acb); } +static void null_timer_cb(void *opaque) +{ + NullAIOCB *acb = opaque; + acb->common.cb(acb->common.opaque, 0); + timer_deinit(&acb->timer); + qemu_aio_unref(acb); +} + static inline BlockAIOCB *null_aio_common(BlockDriverState *bs, BlockCompletionFunc *cb, void *opaque) { NullAIOCB *acb; + BDRVNullState *s = bs->opaque; acb = qemu_aio_get(&null_aiocb_info, bs, cb, opaque); - acb->bh = aio_bh_new(bdrv_get_aio_context(bs), null_bh_cb, acb); - qemu_bh_schedule(acb->bh); + /* Only emulate latency after vcpu is running. */ + if (s->latency_ns && qemu_clock_get_us(QEMU_CLOCK_VIRTUAL) > 0) { + aio_timer_init(bdrv_get_aio_context(bs), &acb->timer, + QEMU_CLOCK_VIRTUAL, SCALE_NS, + null_timer_cb, acb); + timer_mod_ns(&acb->timer, + qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) + s->latency_ns); + } else { + acb->bh = aio_bh_new(bdrv_get_aio_context(bs), null_bh_cb, acb); + qemu_bh_schedule(acb->bh); + } return &acb->common; }