From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ferruh Yigit Subject: Re: [PATCH v5 7/9] net/virtio: support in-order Rx and Tx Date: Tue, 3 Jul 2018 11:36:55 +0100 Message-ID: <22d95bb6-8d26-a183-d173-eeaa62969e0e@intel.com> References: <20180702135642.52577-1-yong.liu@intel.com> <20180702135642.52577-8-yong.liu@intel.com> <7ab59556-5719-e05b-ea1f-f94867d90b24@intel.com> <739c4cea-23c8-f1ec-f186-39b74960cb7b@redhat.com> <86228AFD5BCD8E4EBFD2B90117B5E81E630D188A@SHSMSX103.ccr.corp.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Cc: "Wang, Zhihong" , "dev@dpdk.org" To: "Liu, Yong" , Maxime Coquelin , "Bie, Tiwei" Return-path: Received: from mga18.intel.com (mga18.intel.com [134.134.136.126]) by dpdk.org (Postfix) with ESMTP id 025511BE3D for ; Tue, 3 Jul 2018 12:37:08 +0200 (CEST) In-Reply-To: <86228AFD5BCD8E4EBFD2B90117B5E81E630D188A@SHSMSX103.ccr.corp.intel.com> Content-Language: en-US List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" On 7/3/2018 2:36 AM, Liu, Yong wrote: > > >> -----Original Message----- >> From: Yigit, Ferruh >> Sent: Tuesday, July 03, 2018 12:57 AM >> To: Maxime Coquelin ; Liu, Yong >> ; Bie, Tiwei >> Cc: Wang, Zhihong ; dev@dpdk.org >> Subject: Re: [dpdk-dev] [PATCH v5 7/9] net/virtio: support in-order Rx and >> Tx >> >> On 7/2/2018 5:53 PM, Maxime Coquelin wrote: >>> >>> >>> On 07/02/2018 06:52 PM, Ferruh Yigit wrote: >>>> On 7/2/2018 5:41 PM, Ferruh Yigit wrote: >>>>> On 7/2/2018 2:56 PM, Marvin Liu wrote: >>>>>> IN_ORDER Rx function depends on merge-able feature. Descriptors >>>>>> allocation and free will be done in bulk. >>>>>> >>>>>> Virtio dequeue logic: >>>>>> dequeue_burst_rx(burst mbufs) >>>>>> for (each mbuf b) { >>>>>> if (b need merge) { >>>>>> merge remained mbufs >>>>>> add merged mbuf to return mbufs list >>>>>> } else { >>>>>> add mbuf to return mbufs list >>>>>> } >>>>>> } >>>>>> if (last mbuf c need merge) { >>>>>> dequeue_burst_rx(required mbufs) >>>>>> merge last mbuf c >>>>>> } >>>>>> refill_avail_ring_bulk() >>>>>> update_avail_ring() >>>>>> return mbufs list >>>>>> >>>>>> IN_ORDER Tx function can support offloading features. Packets which >>>>>> matched "can_push" option will be handled by simple xmit function. >> Those >>>>>> packets can't match "can_push" will be handled by original xmit >> function >>>>>> with in-order flag. >>>>>> >>>>>> Virtio enqueue logic: >>>>>> xmit_cleanup(used descs) >>>>>> for (each xmit mbuf b) { >>>>>> if (b can inorder xmit) { >>>>>> add mbuf b to inorder burst list >>>>>> continue >>>>>> } else { >>>>>> xmit inorder burst list >>>>>> xmit mbuf b by original function >>>>>> } >>>>>> } >>>>>> if (inorder burst list not empty) { >>>>>> xmit inorder burst list >>>>>> } >>>>>> update_avail_ring() >>>>>> >>>>>> Signed-off-by: Marvin Liu >>>>>> Reviewed-by: Maxime Coquelin >>>>> >>>>> <...> >>>>> >>>>>> @@ -150,6 +188,83 @@ virtio_xmit_cleanup(struct virtqueue *vq, >> uint16_t num) >>>>>> } >>>>>> } >>>>>> >>>>>> +/* Cleanup from completed inorder transmits. */ >>>>>> +static void >>>>>> +virtio_xmit_cleanup_inorder(struct virtqueue *vq, uint16_t num) >>>>>> +{ >>>>>> + uint16_t i, used_idx, desc_idx, last_idx; >>>>> >>>>> >>>>> Getting following build error [1], from code it looks like false >> positive, but >>>>> to get rid of the build error would it be OK to set initial value to >> "desc_idx"? >>>> >>>> I applied this while merging, if this is wrong please let me know, we >> can fix in >>>> next-net, Thanks. >>> >>> Looks good to me. I didn't catch it with the GCC version I use. >> >> I didn't dig more but I also didn't get the error with regular build, the >> one >> with all DEBUGs enabled and mach=default combination gave the error, not >> sure why. >> > > Ferruh, > I didn't catch this error either. I tried three gcc versions 7.2.0, 7.3.0 and 4.8.3. > May I know your gcc version? gcc [1] with debug enabled [2], giving error [3]. [1] gcc (GCC) 8.1.1 20180502 (Red Hat 8.1.1-1) make T=x86_64-native-linuxapp-gcc config [2] CONFIG_RTE_LIBRTE_VIRTIO_DEBUG_RX=y CONFIG_RTE_LIBRTE_VIRTIO_DEBUG_TX=y CONFIG_RTE_LIBRTE_VIRTIO_DEBUG_DUMP=y [3] .../drivers/net/virtio/virtio_rxtx.c: In function ‘virtio_xmit_cleanup_inorder’: .../drivers/net/virtio/virtio_rxtx.c:195:24: error: ‘desc_idx’ may be used uninitialized in this function [-Werror=maybe-uninitialized] uint16_t i, used_idx, desc_idx, last_idx; ^~~~~~~~ cc1: all warnings being treated as errors > > Thanks, > Marvin > >>> >>> Thanks, >>> Maxime >>> >>>>> >>>>> >>>>> [1] >>>>> .../dpdk/drivers/net/virtio/virtio_rxtx.c:195:24: error: ‘desc_idx’ >> may be used >>>>> uninitialized in this function [-Werror=maybe-uninitialized] >>>>> >>>>> >>>>> uint16_t i, used_idx, desc_idx, last_idx; >>>>> >>>>> >>>>> >>>>> ^~~~~~~~ >>>>> >>>> >