Regarding #2 For some reason the "rte_eth_dev_rss_reta_update" API didn't make a change for Intel NIC if it was called *before* start. (weird I agree) Moving it after start API solve the issue for all the drivers ..
Thanks, Hanoh -----Original Message----- From: Nélio Laranjeiro [mailto:nelio.laranje...@6wind.com] Sent: Thursday, March 22, 2018 2:29 PM To: Hanoch Haim (hhaim) Cc: Yongseok Koh; dev@dpdk.org Subject: Re: [dpdk-dev] mlx5 reta size is dynamic Hi, On Thu, Mar 22, 2018 at 10:59:36AM +0000, Hanoch Haim (hhaim) wrote: > Hi, > > 1) Regarding this sentence, > "Your need is to have a fixed size returned by the > rte_eth_dev_info_get(), the PMD can have an internal dynamic size, it > won't modify your spreading." > > I'm fine with that as long: > > 1. rte_eth_dev_info_get will expose the same *size* 2. > rte_eth_dev_rss_reta_update will behave the as there are reta_size for > *any* random input (will enlarge the table internally to maximum > size) > In other words, from the user prospective you will have static > reta_size. Good, the requirement is clear enough for me i.e. user static RETA table size and spreading accordingly. > 2) "In such situation, changing the RETA means stopping the traffic, > destroying every single flow, hash Rx queue, indirection table to > remake everything with the new configuration. > Until then, we always recommended to any application to restart the > port on this device after a RETA update to apply this new > configuration." > > From an experiment I did, you *can* change it under traffic and it works > without issue. > Drivers tested are: igbe/i40e/mlx5 hmm, it is certainly calling a devops which will end by calling mlx5_traffic_start(). Thanks, > Thanks, > Hanoh > > > -----Original Message----- > From: Nélio Laranjeiro [mailto:nelio.laranje...@6wind.com] > Sent: Thursday, March 22, 2018 12:46 PM > To: Hanoch Haim (hhaim) > Cc: Yongseok Koh; dev@dpdk.org > Subject: Re: [dpdk-dev] mlx5 reta size is dynamic > > Hi Hanoch, > > On Thu, Mar 22, 2018 at 10:00:45AM +0000, Hanoch Haim (hhaim) wrote: > > Hi Nelio, > > > > Let me provide more background. > > The context is TRex running in Advance Stateful (ASTf) mode using > > multi-core. > > In this case the flows are distributed using RSS. New flows (c->s) > > need to have a tuple that will match the generated core. For this > > calculation there is a need of to know the *RETA table size* > > > > > > Code: > > > > /*1. verify that driver can support RSS */ > > rte_eth_dev_info_get(m_repid,&dev_info); > > save_reta_size = dev_info.reta_size > > save_hash_key = dev_info.hash_key_size > > printf("RETA_SIZE : %d \n",save_reta_size); > > printf("HASH_SIZE : %d \n",save_hash_key); > > > > /*2. configure queues */ > > ret = rte_eth_dev_configure(m_repid, > > nb_rx_queue, > > nb_tx_queue, > > eth_conf); > > .. > > > > /* 3. reading the RETA again */ > > rte_eth_dev_info_get(m_repid,&dev_info); > > save_reta_size = dev_info.reta_size << > > save_hash_key = dev_info.hash_key_size > > printf("RETA_SIZE1 : %d \n",save_reta_size); > > > > > > /* 4. update the RETA table */ > > rte_eth_dev_rss_reta_update(m_repid, &reta_conf[0], > > dev_info.reta_size) > > > > > > 2. /*Output in case of Intel i40e*/ > > > > RETA_SIZE : 512 > > HASH_SIZE : 52 > > > > RETA_SIZE1 : 512 > > > > 3. /*Output in case of Mlx5 */ > > > > RETA_SIZE : 512 > > HASH_SIZE : 0 > > > > RETA_SIZE1 : 4 << not round of 64 , depends on the number of > > rx queues > > Your need is to have a fixed size returned by the rte_eth_dev_info_get(), the > PMD can have an internal dynamic size, it won't modify your spreading. > > An information, you are getting the hash key size, according to the > documentation of struct rte_eth_rss_conf, only the i40e can have a key len > different from 40 bytes, others should just ignore the field [1]. > > Regards, > > [1] > https://dpdk.org/browse/dpdk/tree/lib/librte_ether/rte_ethdev.h#n380 > > > Hanoh > > > > -----Original Message----- > > From: Nélio Laranjeiro [mailto:nelio.laranje...@6wind.com] > > Sent: Thursday, March 22, 2018 11:28 AM > > To: Hanoch Haim (hhaim) > > Cc: Yongseok Koh; dev@dpdk.org > > Subject: Re: [dpdk-dev] mlx5 reta size is dynamic > > > > Hi Hanoch, > > > > On Thu, Mar 22, 2018 at 09:02:19AM +0000, Hanoch Haim (hhaim) wrote: > > > Hi Nelio, > > > I think you didn't understand me. I suggest to keep the RETA table > > > size constant (maximum 512 in your case) and don't change its base > > > on the number of configured Rx-queue. > > > > It is even simpler, we can return the maximum size or a multiple of > > RTE_RETA_GROUP_SIZE according to the number of Rx queues being used, > > in the devop->dev_infos_get() as it is what the > > rte_eth_dev_rss_reta_update() implementation will expect. > > > > > This will make the DPDK API consistent. As a user I need to do > > > tricks (allocate an odd/prime number of rx-queues) to get the RETA > > > size constant at 512 > > > > I understand this issue, what I don't fully understand your needs. > > > > > I'm not talking about changing the values in the RETA table which > > > can be done while there is traffic. > > > > On MLX5 changing the entries of the RETA table don't affect the current > > traffic, it needs a port restart to affect it and only for "default" > > flows, any flow created through the public flow API are not impacted by the > > RETA table. > > > > > > From my understanding, you wish to have a size returned by > > devop->dev_infos_get() usable directly by rte_eth_dev_rss_reta_update(). > > This is why you are asking for a fix size? So, if internally the PMD > > starts with a smaller RETA table does not really matter, until the RETA API > > works without any trick from the application side. Is this correct? > > > > Thanks, > > > > > Thanks, > > > Hanoh > > > > > > > > > -----Original Message----- > > > From: Nélio Laranjeiro [mailto:nelio.laranje...@6wind.com] > > > Sent: Thursday, March 22, 2018 10:55 AM > > > To: Hanoch Haim (hhaim) > > > Cc: Yongseok Koh; dev@dpdk.org > > > Subject: Re: [dpdk-dev] mlx5 reta size is dynamic > > > > > > On Thu, Mar 22, 2018 at 06:52:53AM +0000, Hanoch Haim (hhaim) wrote: > > > > Hi Yongseok, > > > > > > > > > > > > RSS has a DPDK API,application can ask for the reta table size > > > > and configure it. In your case you are assuming specific use > > > > case and change the size dynamically which solve 90% of the > > > > use-cases but break the 10% use-case. > > > > Instead, you could provide the application a consistent API and > > > > with that 100% of the applications can work with no issue. This > > > > is what happen with Intel (ixgbe/i40e) Another minor issue the > > > > rss_key_size return as zero but internally it is 40 bytes > > > > > > Hi Hanoch, > > > > > > Legacy DPDK API has always considered there is only a single indirection > > > table aka. RETA whereas this is not true [1][2] on this device. > > > > > > On MLX5 there is an indirection table per Hash Rx queue according to the > > > list of queues making part of it. > > > The Hash Rx queue is configured to make the hash with configured > > > information: > > > - Algorithm, > > > - key > > > - hash field (Verbs hash field) > > > - Indirection table > > > An Hash Rx queue cannot handle multiple RSS configuration, we have an > > > Hash Rx queue per protocol and thus a full configuration per protocol. > > > > > > In such situation, changing the RETA means stopping the traffic, > > > destroying every single flow, hash Rx queue, indirection table to remake > > > everything with the new configuration. > > > Until then, we always recommended to any application to restart the port > > > on this device after a RETA update to apply this new configuration. > > > > > > Since the flow API is the new way to configure flows, application should > > > move to this new one instead of using old API for such behavior. > > > We should also remove such devop from the PMD to avoid any confusion. > > > > > > Regards, > > > > > > > Thanks, > > > > Hanoh > > > > > > > > -----Original Message----- > > > > From: Yongseok Koh [mailto:ys...@mellanox.com] > > > > Sent: Wednesday, March 21, 2018 11:48 PM > > > > To: Hanoch Haim (hhaim) > > > > Cc: dev@dpdk.org > > > > Subject: Re: [dpdk-dev] mlx5 reta size is dynamic > > > > > > > > On Wed, Mar 21, 2018 at 06:56:33PM +0000, Hanoch Haim (hhaim) wrote: > > > > > Hi mlx5 driver expert, > > > > > > > > > > DPDK: 17.11 > > > > > Any reason mlx5 driver change the rate table size dynamically > > > > > based on the rx- queues# ? > > > > > > > > The device only supports 2^n-sized indirection table. For example, if > > > > the number of Rx queues is 6, device can't have 1-1 mapping but the > > > > size of ind tbl could be 8, 16, 32 and so on. If we configure it as 8 > > > > for example, 2 out of 6 queues will have 1/4 of traffic while the rest > > > > 4 queues receives 1/8. We thought it was too much disparity and > > > > preferred setting the max size in order to mitigate the imbalance. > > > > > > > > > There is a hidden assumption that the user wants to distribute > > > > > the packets evenly which is not always correct. > > > > > > > > But it is mostly correct because RSS is used for uniform distribution. > > > > The decision wasn't made based on our speculation but by many request > > > > from multiple customers. > > > > > > > > > /* If the requested number of RX queues is not a power of two, use the > > > > > * maximum indirection table size for better balancing. > > > > > * The result is always rounded to the next power of two. */ > > > > > reta_idx_n = (1 << log2above((rxqs_n & (rxqs_n - 1)) ? > > > > > priv->ind_table_max_size : > > > > > rxqs_n)); > > > > > > > > Thanks, > > > > Yongseok > > > > > > [1] https://dpdk.org/ml/archives/dev/2015-October/024668.html > > > [2] https://dpdk.org/ml/archives/dev/2015-October/024669.html > > > > > > -- > > > Nélio Laranjeiro > > > 6WIND > > > > -- > > Nélio Laranjeiro > > 6WIND > > -- > Nélio Laranjeiro > 6WIND -- Nélio Laranjeiro 6WIND
