From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:43603) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YTKez-0006Nc-Oe for qemu-devel@nongnu.org; Wed, 04 Mar 2015 20:33:10 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1YTKew-0000Zj-JO for qemu-devel@nongnu.org; Wed, 04 Mar 2015 20:33:09 -0500 Received: from mx1.redhat.com ([209.132.183.28]:50119) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YTKew-0000Ze-Cl for qemu-devel@nongnu.org; Wed, 04 Mar 2015 20:33:06 -0500 Received: from int-mx11.intmail.prod.int.phx2.redhat.com (int-mx11.intmail.prod.int.phx2.redhat.com [10.5.11.24]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id t251X5Ne006589 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL) for ; Wed, 4 Mar 2015 20:33:05 -0500 From: Fam Zheng Date: Thu, 5 Mar 2015 09:32:58 +0800 Message-Id: <1425519178-17863-1-git-send-email-famz@redhat.com> Subject: [Qemu-devel] [PATCH v2] block/null: Latency simulation by adding new option "latency_ns" List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: Kevin Wolf , Stefan Hajnoczi 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 --- v2: Check for negative value; add sleep in null-co://. [Kevin] --- block/null.c | 55 ++++++++++++++++++++++++++++++++++++++++++++++++++----- 1 file changed, 50 insertions(+), 5 deletions(-) diff --git a/block/null.c b/block/null.c index ec2bd27..7091164 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 +53,11 @@ 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); + if (s->latency_ns < 0) { + error_setg(errp, "latency_ns is invalid"); + } qemu_opts_del(opts); return 0; } @@ -58,28 +72,41 @@ static int64_t null_getlength(BlockDriverState *bs) return s->length; } +static coroutine_fn int null_co_common(BlockDriverState *bs) +{ + BDRVNullState *s = bs->opaque; + + /* Only emulate latency after vcpu is running. */ + if (s->latency_ns && qemu_clock_get_us(QEMU_CLOCK_VIRTUAL) > 0) { + co_aio_sleep_ns(bdrv_get_aio_context(bs), QEMU_CLOCK_VIRTUAL, + s->latency_ns); + } + return 0; +} + static coroutine_fn int null_co_readv(BlockDriverState *bs, int64_t sector_num, int nb_sectors, QEMUIOVector *qiov) { - return 0; + return null_co_common(bs); } static coroutine_fn int null_co_writev(BlockDriverState *bs, int64_t sector_num, int nb_sectors, QEMUIOVector *qiov) { - return 0; + return null_co_common(bs); } static coroutine_fn int null_co_flush(BlockDriverState *bs) { - return 0; + return null_co_common(bs); } typedef struct { BlockAIOCB common; QEMUBH *bh; + QEMUTimer timer; } NullAIOCB; static const AIOCBInfo null_aiocb_info = { @@ -94,15 +121,33 @@ 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; } -- 1.9.3