From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from dpdk.org (dpdk.org [92.243.14.124]) by dpdk.space (Postfix) with ESMTP id EE359A00E6 for ; Tue, 19 Mar 2019 14:47:58 +0100 (CET) Received: from [92.243.14.124] (localhost [127.0.0.1]) by dpdk.org (Postfix) with ESMTP id 4E149493D; Tue, 19 Mar 2019 14:47:58 +0100 (CET) Received: from mx1.redhat.com (mx1.redhat.com [209.132.183.28]) by dpdk.org (Postfix) with ESMTP id 25AA72C54 for ; Tue, 19 Mar 2019 14:47:56 +0100 (CET) Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 8656A3087933; Tue, 19 Mar 2019 13:47:55 +0000 (UTC) Received: from localhost (dhcp-192-225.str.redhat.com [10.33.192.225]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 3483060F94; Tue, 19 Mar 2019 13:47:52 +0000 (UTC) Date: Tue, 19 Mar 2019 14:47:51 +0100 From: Jens Freimann To: Maxime Coquelin Cc: Tiwei Bie , zhihong.wang@intel.com, dev@dpdk.org Message-ID: <20190319134751.ibgaalfravjm77lh@jenstp.localdomain> References: <20190319064312.13743-1-tiwei.bie@intel.com> <20190319064312.13743-6-tiwei.bie@intel.com> <20190319094432.iap4i7ffs6soukr7@jenstp.localdomain> <20190319100939.GA3839@dpdk-tbie.sh.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset="UTF-8"; format="flowed" Content-Disposition: inline In-Reply-To: User-Agent: NeoMutt/20180716 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.45]); Tue, 19 Mar 2019 13:47:55 +0000 (UTC) Subject: Re: [dpdk-dev] [PATCH 05/10] net/virtio: refactor virtqueue structure X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" Message-ID: <20190319134751.3qr1YUlrWZSFeVSStNBZR_wco-tVU2Ma28LkD-01-nI@z> On Tue, Mar 19, 2019 at 02:28:30PM +0100, Maxime Coquelin wrote: > > >On 3/19/19 11:09 AM, Tiwei Bie wrote: >>On Tue, Mar 19, 2019 at 10:44:32AM +0100, Jens Freimann wrote: >>>On Tue, Mar 19, 2019 at 02:43:07PM +0800, Tiwei Bie wrote: >>>>Put split ring and packed ring specific fields into separate >>>>sub-structures, and also union them as they won't be available >>>>at the same time. >>>> >>>>Signed-off-by: Tiwei Bie >>>>--- >>>>drivers/net/virtio/virtio_ethdev.c | 71 +++++++++--------- >>>>drivers/net/virtio/virtio_rxtx.c | 66 ++++++++--------- >>>>drivers/net/virtio/virtio_rxtx_simple.h | 2 +- >>>>drivers/net/virtio/virtio_rxtx_simple_neon.c | 2 +- >>>>drivers/net/virtio/virtio_rxtx_simple_sse.c | 2 +- >>>>drivers/net/virtio/virtqueue.c | 6 +- >>>>drivers/net/virtio/virtqueue.h | 77 +++++++++++--------- >>>>7 files changed, 117 insertions(+), 109 deletions(-) >>>> >>>[snip] >>>... >>>>diff --git a/drivers/net/virtio/virtqueue.h b/drivers/net/virtio/virtqueue.h >>>>index 80c0c43c3..48b3912e6 100644 >>>>--- a/drivers/net/virtio/virtqueue.h >>>>+++ b/drivers/net/virtio/virtqueue.h >>>>@@ -191,17 +191,22 @@ struct vq_desc_extra { >>>> >>>>struct virtqueue { >>>> struct virtio_hw *hw; /**< virtio_hw structure pointer. */ >>>>- struct vring vq_ring; /**< vring keeping desc, used and avail */ >>>>- struct vring_packed ring_packed; /**< vring keeping descs */ >>>>- bool used_wrap_counter; >>>>- uint16_t cached_flags; /**< cached flags for descs */ >>>>- uint16_t event_flags_shadow; >>>>+ union { >>>>+ struct { >>>>+ /**< vring keeping desc, used and avail */ >>>>+ struct vring ring; >>>>+ } vq_split; >>>> >>>>- /** >>>>- * Last consumed descriptor in the used table, >>>>- * trails vq_ring.used->idx. >>>>- */ >>>>- uint16_t vq_used_cons_idx; >>>>+ struct { >>>>+ /**< vring keeping descs and events */ >>>>+ struct vring_packed ring; >>>>+ bool used_wrap_counter; >>>>+ uint16_t cached_flags; /**< cached flags for descs */ >>>>+ uint16_t event_flags_shadow; >>>>+ } vq_packed; >>>>+ }; >>>>+ >>>>+ uint16_t vq_used_cons_idx; /**< last consumed descriptor */ >>>> uint16_t vq_nentries; /**< vring desc numbers */ >>>> uint16_t vq_free_cnt; /**< num of desc available */ >>>> uint16_t vq_avail_idx; /**< sync until needed */ >>> >>>Honest question: What do we really gain by putting it in a union? We >>>save a little memory. But we also make code less readable IMHO. >> >>I think it will make it clear that fields like used_wrap_counter >>are only available in packed ring which will make the code more >>readable. >> >>> >>>If we do this, can we at least shorten some variable names, like drop >>>the vq_ prefix? (It's used everywhere like vq->vq_packed*, so with >>>vq->packed* we don't loose any context). >> >>I prefer to have consistent prefix like most fields in this >>structure (although some fields don't really follow this). > >As Jens, I tend to agree that the vq_ prefix is quite redundant. >However, I think it is better to keep it in this patch for consistency. > >Maybe it can be remove in a separate patch later? I thought it might be convenient to change it now as we are touching all related code anyway. But I also don't want to block the patch because of this cosmetic thing. So let's defer it to a later patch set. regards, Jens