From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:46176) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZFGMa-0000Qs-Jv for qemu-devel@nongnu.org; Wed, 15 Jul 2015 02:40:17 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZFGMX-0004UX-7o for qemu-devel@nongnu.org; Wed, 15 Jul 2015 02:40:16 -0400 Received: from mx1.redhat.com ([209.132.183.28]:52331) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZFGMX-0004U3-0a for qemu-devel@nongnu.org; Wed, 15 Jul 2015 02:40:13 -0400 Received: from int-mx10.intmail.prod.int.phx2.redhat.com (int-mx10.intmail.prod.int.phx2.redhat.com [10.5.11.23]) by mx1.redhat.com (Postfix) with ESMTPS id 60D1733B36E for ; Wed, 15 Jul 2015 06:40:11 +0000 (UTC) Date: Wed, 15 Jul 2015 12:09:57 +0530 From: Amit Shah Message-ID: <20150715063957.GL10280@grmbl.mre> References: <1436859190-20002-1-git-send-email-pagupta@redhat.com> <1436859190-20002-3-git-send-email-pagupta@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1436859190-20002-3-git-send-email-pagupta@redhat.com> Subject: Re: [Qemu-devel] [PATCH 2/2 v2] virtio-rng: Serve pending request if any after timer bumps up quota. List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Pankaj Gupta Cc: qemu-devel@nongnu.org, mst@redhat.com On (Tue) 14 Jul 2015 [13:03:10], Pankaj Gupta wrote: > We are arming timer when we get first request from guest. > Even if guest pulls all the data we will be serving guest > only when timer bumps up new quota. When timer expires > we check if we have a pending request from guest, we > serve it and rearm the timer else we don't do any thing. > > This patch also moves out 'request size' logic out to > 'check_request' function so that can be re-used. > > Signed-off-by: Pankaj Gupta > --- > hw/virtio/virtio-rng.c | 36 ++++++++++++++++++++++++------------ > 1 file changed, 24 insertions(+), 12 deletions(-) > > diff --git a/hw/virtio/virtio-rng.c b/hw/virtio/virtio-rng.c > index 8774a0c..dca5064 100644 > --- a/hw/virtio/virtio-rng.c > +++ b/hw/virtio/virtio-rng.c > @@ -37,6 +37,24 @@ static size_t get_request_size(VirtQueue *vq, unsigned quota) > return in; > } > > +static size_t check_request(VirtIORNG *vrng) > +{ > + size_t size; > + unsigned quota; > + > + if (vrng->quota_remaining < 0) { > + quota = 0; > + } else { > + quota = MIN((uint64_t)vrng->quota_remaining, (uint64_t)UINT32_MAX); > + } > + size = get_request_size(vrng->vq, quota); > + > + trace_virtio_rng_request(vrng, size, quota); > + > + size = MIN(vrng->quota_remaining, size); > + return size; > +} > + > static void virtio_rng_process(VirtIORNG *vrng); > > /* Send data from a char device over to the guest */ > @@ -72,7 +90,6 @@ static void chr_read(void *opaque, const void *buf, size_t size) > static void virtio_rng_process(VirtIORNG *vrng) > { > size_t size; > - unsigned quota; > > if (!is_guest_ready(vrng)) { > return; > @@ -83,17 +100,8 @@ static void virtio_rng_process(VirtIORNG *vrng) > qemu_clock_get_ms(QEMU_CLOCK_VIRTUAL) + vrng->conf.period_ms); > vrng->activate_timer = false; > } > + size = check_request(vrng); > > - if (vrng->quota_remaining < 0) { > - quota = 0; > - } else { > - quota = MIN((uint64_t)vrng->quota_remaining, (uint64_t)UINT32_MAX); > - } > - size = get_request_size(vrng->vq, quota); > - > - trace_virtio_rng_request(vrng, size, quota); > - > - size = MIN(vrng->quota_remaining, size); > if (size) { > rng_backend_request_entropy(vrng->rng, size, chr_read, vrng); > } > @@ -142,9 +150,13 @@ static int virtio_rng_load(QEMUFile *f, void *opaque, int version_id) > static void check_rate_limit(void *opaque) > { > VirtIORNG *vrng = opaque; > + size_t size; > > vrng->quota_remaining = vrng->conf.max_bytes; > - virtio_rng_process(vrng); > + size = check_request(vrng); > + if (size > 0) { > + virtio_rng_process(vrng); > + } Why is it necessary to call check_request() here, instead of just calling get_request_size()? We want to call virtio_rng_process() in case the guest has queued up another buffer, and for that, get_request_size() is sufficient. check_request() is anyway something that virtio_rng_process() is going to do as soon as it's called... Amit