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charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-AuthSource: MWHPR11MB1838.namprd11.prod.outlook.com X-MS-Exchange-CrossTenant-Network-Message-Id: 8dfe9d78-a04a-48d9-02d5-08d874da197a X-MS-Exchange-CrossTenant-originalarrivaltime: 20 Oct 2020 09:25:34.9645 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 46c98d88-e344-4ed4-8496-4ed7712e255d X-MS-Exchange-CrossTenant-mailboxtype: HOSTED X-MS-Exchange-CrossTenant-userprincipalname: O0w4RQ6k3Fl+M2k1mzguWBB19+oTRxuBgwuCUnzqMuT9Kepprj1cJzlG4lRjKwp4FUb+GaBs4Ijl7n313q0lFvKzYTqglyZe9oRbLgAcuAw= X-MS-Exchange-Transport-CrossTenantHeadersStamped: MWHPR1101MB2304 X-OriginatorOrg: intel.com Subject: Re: [dpdk-dev] [v2 1/2] cryptodev: support enqueue callback functions 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" Hi Honnappa, I will send out the next version of the patch soon. Regards Abhinandan > -----Original Message----- > From: Honnappa Nagarahalli > Sent: Tuesday, October 20, 2020 3:34 AM > To: Ananyev, Konstantin ; Gujjar, Abhinanda= n S > ; dev@dpdk.org; Doherty, Declan > > Cc: jerinj@marvell.com; Akhil.goyal@nxp.com; Vangati, Narender > ; nd ; Honnappa Nagarahalli > ; nd > Subject: RE: [dpdk-dev] [v2 1/2] cryptodev: support enqueue callback func= tions >=20 > >=20 > > > > > > Hi Abhinandan, > > > > > > > > > > > > > > > > > > > > Hi Konstantin & Honnappa, > > > > > > > > > > > > > > Thanks for all the inputs and feedback. > > > > > > > > > > > > > > @Ananyev, Konstantin, > > > > > > > I have measured the perf with and without callback on xeon. > > > > > > > Here are the > > > > > > numbers: > > > > > > > > > > > > > > ./app/dpdk-test-crypto-perf -l 6-7 > > > > > > > --vdev=3D"crypto_openssl0,socket_id=3D0,max_nb_sessions=3D128= " -- > > > > > > > --ptest throughput --devtype crypto_openssl --optype > > > > > > > cipher-then-auth --cipher-algo aes-cbc --cipher-op encrypt > > > > > > > --cipher-key-sz 16 --auth-algo sha1-hmac --auth-op generate > > > > > > > --auth-key-sz 64 --digest-sz > > > > > > > 12 --total-ops 10000000 --burst-sz 32 --buffer-sz 64 > > > > > > > > > > > > > > With callback(+ RCU - totally opaque to data-plane threads) > > > > > > > lcore id Buf Size Burst Size Enqueued Dequeued = Failed Enq > > > > Failed > > > > > > Deq MOps Gbps Cycles/Buf > > > > > > > 7 64 32 10000000 = 10000000 0 > 0 > > > > > > 0.8129 0.4162 2694.09 > > > > > > > 7 64 32 10000000 = 10000000 0 > 0 > > > > > > 0.8152 0.4174 2686.31 > > > > > > > 7 64 32 10000000 = 10000000 0 > 0 > > > > > > 0.8198 0.4197 2671.48 > > > > > > > > > > > > > > Without callback: > > > > > > > lcore id Buf Size Burst Size Enqueued Dequeued = Failed Enq > > > > Failed > > > > > > Deq MOps Gbps Cycles/Buf > > > > > > > > > > > > > > 7 64 32 10000000 = 10000000 0 > 0 > > > > > > 0.8234 0.4216 2659.81 > > > > > > > 7 64 32 10000000 = 10000000 0 > 0 > > > > > > 0.8247 0.4222 2655.63 > > > > > > > 7 64 32 10000000 = 10000000 0 > 0 > > > > > > 0.8123 0.4159 2695.90 > > > > > > > > > > > > > > > > > > Just to cofirm: > > > > > > You implemented crypto enqueue callbacks using RCU QSBR online > > > > > > /offline (as suggested below) and numbers above are for: > > > > > > 1) callback code in place and some dummy callback installed > > > > > That's right. (+ RCU calling online + offline APIs inside > > > > > rte_cryptodev_enqueue_burst()) > > > > > > 2) callback code in place but no callbacks installed > > > > > No callback code. i.e. Original code. > > > > > > > > Ok, and if I get things right - difference between mean values is ~= 15 > cycles? > > > Yes. May be, number are more stable on isolated core. Let's consider > > > worst > > case too. > > > > Ok. > > > > > > That's seems like very good result to me. > > > > Can I suggest to run one more test for your new callback code in > > > > place, but no actual callbacks installed? > > > lcore id Buf Size Burst Size Enqueued Dequeued Failed = Enq Failed > Deq > > MOps Gbps Cycles/Buf > > > > > > 7 64 32 10000000 10000000 = 0 0 > 0.8220 > > 0.4209 2664.12 > > > 7 64 32 10000000 10000000 = 0 0 > 0.8245 > > 0.4221 2656.14 > > > 7 64 32 10000000 10000000 = 0 0 > 0.8261 > > 0.4229 2651.15 > > > > So, if I can read numbers properly for not-armed callback impact is > neglectable. > > It is hard to say much without seeing the actual code, but from the > > numbers above, I think it is a good result and we can go ahead with tha= t > approach. > > Honnappa, Akhil, Jerin do you have any objections to such approach in > principle? > The numbers look good. I guess this needs to be tested on Arm platforms a= s > well. It would be good to get the next version of the patch (along with t= he test > case), others can test from there. >=20 > > Konstantin > > > > > > Thanks > > > > Konstantin > > > > > > > > > > > > > > > > Is my understanding correct here? > > > > > > Thanks > > > > > > Konstantin > > > > > > > > > > > > > > > > > > > > > > > > > > Regards > > > > > > > Abhinandan > > > > > > > > > > > > > > > -----Original Message----- > > > > > > > > From: Ananyev, Konstantin > > > > > > > > Sent: Tuesday, September 29, 2020 2:33 PM > > > > > > > > To: Honnappa Nagarahalli ; > > > > > > > > Gujjar, Abhinandan S ; > > > > > > > > dev@dpdk.org; Doherty, Declan > > > > > > > > Cc: jerinj@marvell.com; Akhil.goyal@nxp.com; Vangati, > > > > > > > > Narender ; nd ; nd > > > > > > > > > > > > > > > > Subject: RE: [dpdk-dev] [v2 1/2] cryptodev: support > > > > > > > > enqueue callback functions > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > +#ifdef RTE_CRYPTODEV_CALLBACKS int > > > > > > > > > > > > > > > > > > > +rte_cryptodev_rcu_qsbr_add(uint8_t > > > > > > > > > > > > > > > > > > > +dev_id, struct rte_rcu_qsbr > > > > > > > > > > > > > > > > > > > +*qsbr) { > > > > > > > > > > > > > > > > > > > + > > > > > > > > > > > > > > > > > > > + struct rte_cryptodev *dev; > > > > > > > > > > > > > > > > > > > + > > > > > > > > > > > > > > > > > > > + if > (!rte_cryptodev_pmd_is_valid_dev(dev_id)) { > > > > > > > > > > > > > > > > > > > + CDEV_LOG_ERR("Invalid > dev_id=3D%" > > > > > > PRIu8, > > > > > > > > > > dev_id); > > > > > > > > > > > > > > > > > > > + return -EINVAL; > > > > > > > > > > > > > > > > > > > + } > > > > > > > > > > > > > > > > > > > + > > > > > > > > > > > > > > > > > > > + dev =3D &rte_crypto_devices[dev_id]= ; > > > > > > > > > > > > > > > > > > > + dev->qsbr =3D qsbr; > > > > > > > > > > > > > > > > > > > + return 0; } > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > So if I understand your patch > > > > > > > > > > > > > > > > > > correctly you propose a new working > > > > > > > > > > > > > > > > > > model for > > > > > > > > > > > > > > > > > > crypto-devs: > > > > > > > > > > > > > > > > > > 1. Control-plane has to allocate/setup > > > > > > > > > > > > > > > > > > rcu_qsbr and do rte_cryptodev_rcu_qsbr_= add(). > > > > > > > > > > > > > > > > > > 2. Data-plane has somehow to obtain > > > > > > > > > > > > > > > > > > pointer to that rcu_qsbr and wrap > > > > > > > > > > > > > > > > > > cryptodev_enqueue() > > > > > > > > > > > > > > > > > > with rcu_qsbr_quiescent() or > > > > > > > > > > > > rcu_qsbr_online()/rcu_qsbr_offline(). > > > > > > > > > > > > > > > > > Yes. I think, it is not a new model. It > > > > > > > > > > > > > > > > > is same as RCU integration with > > > > > > > > > > > > > > LPM. > > > > > > > > > > > > > > > > > Please refer: > > > > > > > > > > > > > > > > > https://patches.dpdk.org/cover/73673/ > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > I am talking about new working model for > > > > > > > > > > > > > > > > crypto-dev > > > > > > > > > > > > enqueue/dequeue. > > > > > > > > > > > > > > > > As I said above now it becomes data-plane > > > > > > > > > > > > > > > > thread responsibility > > > > > > > > to: > > > > > > > > > > > > > > > > -somehow to obtain pointer to that > > > > > > > > > > > > > > > > rcu_qsbr for each cryptodev it is > > > > > > > > > > > > > > using. > > > > > > > > > > > > > > > > -call rcu sync functions > > > > > > > > > > > > > > > > (quiescent/online/offline) on a regular > > > > > > > > > > basis. > > > > > > > > > > > > > > > It is not on regular basis. When data plane > > > > > > > > > > > > > > > comes up, they report > > > > > > > > > > online. > > > > > > > > > > > > > > > They report quiescent when they are done > > > > > > > > > > > > > > > with critical section or shared > > > > > > > > > > > > > > structure. > > > > > > > > > > > > > > > > > > > > > > > > > > > > I understand that, but it means all existing > > > > > > > > > > > > > > apps have to be changed that > > > > > > > > > > > > way. > > > > > > > > > > > > > > > > > > > > > > > > > > > > > All though, there is some dataplane changes > > > > > > > > > > > > > > > involved here, I don't think, it > > > > > > > > > > > > > > is major. > > > > > > > > > > > > > > > > > > > > > > > > > > > > I still think our goal here should be to make > > > > > > > > > > > > > > no visible changes to the dataplane. > > > > > > > > > > > > > > I.E. all necessary data-plane changes need to > > > > > > > > > > > > > > be hidden inside CB invocation part. > > > > > > > > > > > > > Please note that this is being implemented using > > > > > > > > > > > > > the memory reclamation framework documented at > > > > > > > > > > > > > https://doc.dpdk.org/guides/prog_guide/rcu_lib.h > > > > > > > > > > > > > tm > > > > > > > > > > > > > l#re > > > > > > > > > > > > > sour > > > > > > > > > > > > > ce-r > > > > > > > > > > > > > ecla > > > > > > > > > > > > > mati > > > > > > > > > > > > > on-framework-for-dpdk > > > > > > > > > > > > > > > > > > > > > > > > > > While using RCU there are couple of trade-offs > > > > > > > > > > > > > that applications have to > > > > > > > > > > > > consider: > > > > > > > > > > > > > 1) Performance - reporting the quiescent state > > > > > > > > > > > > > too often results in performance impact on data > > > > > > > > > > > > > plane > > > > > > > > > > > > > 2) Amount of outstanding memory to reclaim - > > > > > > > > > > > > > reporting less often results in more outstanding > > > > > > > > > > > > > memory to reclaim > > > > > > > > > > > > > > > > > > > > > > > > > > Hence, the quiescent state reporting is left to t= he > application. > > > > > > > > > > > > > The application decides how often it reports the > > > > > > > > > > > > > quiescent state and has control > > > > > > > > > > > > over the data plane performance and the > > > > > > > > > > > > outstanding memory to > > > > > > > > reclaim. > > > > > > > > > > > > > > > > > > > > > > > > > > When you say "new working model for crypto-dev > > > > > > > > > > > > > enqueue/dequeue", > > > > > > > > > > > > > > > > > > > > > > > > > > 1) are you comparing these with existing > > > > > > > > > > > > > crypto-dev enqueue/dequeue > > > > > > > > > > > > APIs? If yes, these are new APIs, it is not breakin= g anything. > > > > > > > > > > > > > 2) are you comparing these with existing call > > > > > > > > > > > > > back functions in ethdev enqueue/dequeue APIs? > > > > > > > > > > > > > If yes, agree that this is a new model. But, it > > > > > > > > > > > > > is > > > > > > > > > > > > possible to support what ethdev supports along > > > > > > > > > > > > with the RCU method used in this patch. > > > > > > > > > > > > > > > > > > > > > > > > What I am talking about: > > > > > > > > > > > > > > > > > > > > > > > > Existing cryptodev enqueue/dequeue model doesn't > > > > > > > > > > > > require for the user to manage any RCU QSBR state > manually. > > > > > > > > > > > > I believe that addition of ability to add/remove > > > > > > > > > > > > enqueue/dequeue callbacks shouldn't change > > > > > > > > > > > > existing working > > > > > > model. > > > > > > > > > > > > I think that adding/removing such callbacks has to > > > > > > > > > > > > be opaque to the user DP code and shouldn't > > > > > > > > > > > > require user to change > > > > it. > > > > > > > > > > > > Same as we have now for ethdev callback implementat= ion. > > > > > > > > > > > The ethdev callback implementation conveniently > > > > > > > > > > > leaves the problem of > > > > > > > > > > freeing memory to the user to resolve, it does not > > > > > > > > > > handle the > > issue. > > > > > > > > > > > Hence, it "looks" to be opaque to the DP code. > > > > > > > > > > > However, if the application has to implement a safe > > > > > > > > > > > way to free the call back memory, its > > > > > > > > > > DP is affected based on call backs are being used or no= t. > > > > > > > > > > > > > > > > > > > > Yes, I think that's big drawback in initial ethdev > > > > > > > > > > callback implementation - it simply ignores DP/CP sync > > > > > > > > > > problem > > completely. > > > > > > > > > > Though I think it is possible to have both here: > > > > > > > > > > keep callback "opaque" to DP code and provide some > > > > > > > > > > sync mechanism between DP/CP. > > > > > > > > > > Hopefully one day we can fix ethdev callbacks too. > > > > > > > > > The solution we develop can be used in ethdev too. > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > I think that forcing DP code to be aware that > > > > > > > > > > > > callbacks are present or not and to modify its > > > > > > > > > > > > behaviour depending on that nearly voids the > > > > > > > > > > > > purpose of > > having callbacks at all. > > > > > > > > > > > > In that case DP can just invoke callback function > > > > > > > > > > > > directly from it's > > > > > > > > > > codepath . > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > Note that now data-plane thread would have > > > > > > > > > > > > > > > > to do that always > > > > > > > > > > > > > > > > - even if there are now callbacks > > > > > > > > > > > > > > > > installed for that cryptodev queue > > > > > > > > > > > > right now. > > > > > > > > > > > > > > > > All that changes behaviour of existing > > > > > > > > > > > > > > > > apps and I presume would reduce adoption of= that > fature. > > > > > > > > > > > > > If I understand this correct, you are talking > > > > > > > > > > > > > about a case where in the application might be > > > > > > > > > > > > > registering/unregistering multiple times during > > > > > > > > > > > > > its lifetime. In this case, yes, the application > > > > > > > > > > > > > might be reporting the > > > > > > > > > > > > quiescent state even when it has not registered the= call > backs. > > > > > > > > > > > > But, it has the flexibility to not report it if it > > > > > > > > > > > > implements additional > > > > > > logic. > > > > > > > > > > > > > Note that we are assuming that the application > > > > > > > > > > > > > has to report quiescent state only for using call= back > functions. > > > > > > > > > > > > > Most probably the application has > > > > > > > > > > > > other requirements to use RCU. > > > > > > > > > > > > > Why not support what is done for ethdev call > > > > > > > > > > > > > back functions along with > > > > > > > > > > > > providing RCU method? > > > > > > > > > > > > > > > > > > > > > > > > > > > > There is always trade off involved! > > > > > > > > > > > > > > > In the previous patch, you suggested that > > > > > > > > > > > > > > > some lazy app may not free up the memory allo= cated > by add cb. > > > > > > > > > > > > > > > For such apps, this patch has sync mechanism > > > > > > > > > > > > > > > with some additional cost of CP & DP > > > > > > > > > > changes. > > > > > > > > > > > > > > > > > > > > > > > > > > > > Sigh, it is not about laziness of the app. > > > > > > > > > > > > > > The problem with current ethedev cb mechanism > > > > > > > > > > > > > > and yours > > > > > > > > > > > > > > V1 (which was just a clone of it) - CP doesn't > > > > > > > > > > > > > > know when it is safe after CB removal to free > > > > > > > > > > > > > > related > > memory. > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > I still think all this callback mechanism > > > > > > > > > > > > > > > > should be totally opaque to data-plane > > > > > > > > > > > > > > > > threads - user shouldn't change his app > > > > > > > > > > > > > > > > code depending on would some > > > > > > > > > > > > > > > > enqueue/dequeue callbacks be > > > > > > > > > > > > installed or not. > > > > > > > > > > > > > > > I am not sure, how that can be implemented > > > > > > > > > > > > > > > with existing RCU > > > > > > > > > > design. > > > > > > > > > > > > > > > > > > > > > > > > > > > > As I said below the simplest way - with > > > > > > > > > > > > > > calling rcu onine/offline inside CB invocation = block. > > > > > > > > > > > > > > That's why I asked you - did you try that > > > > > > > > > > > > > > approach and what is the perf numbers? > > > > > > > > > > > > > > I presume with no callbacks installed the perf > > > > > > > > > > > > > > change should be nearly > > > > > > > > > > > > zero. > > > > > > > > > > > > > > > > > > > > > > > > > > > > > @Honnappa Nagarahalli, Do you have any > suggestions? > > > > > > > > > > > > > Reporting quiescent state in the call back > > > > > > > > > > > > > functions has several > > > > > > > > > > > > disadvantages: > > > > > > > > > > > > > 1) it will have performance impacts and the > > > > > > > > > > > > > impacts will increase as the > > > > > > > > > > > > number of data plane threads increase. > > > > > > > > > > > > > 2) It will require additional configuration > > > > > > > > > > > > > parameters to control how often the quiescent > > > > > > > > > > > > > state is reported to control the performance > > > > > > > > > > impact. > > > > > > > > > > > > > 3) Does not take advantage of the fact that most > > > > > > > > > > > > > probably the application is using RCU already > > > > > > > > > > > > > 4) There are few difficulties as well, please see= below. > > > > > > > > > > > > > > > > > > > > > > > > I suggested Abhinandan to use RCU library because > > > > > > > > > > > > it is already there, and I thought it would be > > > > > > > > > > > > good not to re-implement > > > > > > the wheel. > > > > > > > > > > > > Though if you feel librte_rcu doesn't match that > > > > > > > > > > > > task - fine, let's do it without librte_rcu. > > > > > > > > > > > > After all, what we need here - just an atomic ref > > > > > > > > > > > > count per queue that we are going to increment at > > > > > > > > > > > > entering and leaving list of callbacks inside > enqueue/dequeue. > > > > > > > > > > > Ok, looks like I missed the point that a queue is > > > > > > > > > > > used by a single data plane > > > > > > > > > > thread. > > > > > > > > > > > Along with ref count increment you need the memory > > > > > > > > > > > orderings to avoid > > > > > > > > > > race conditions. These will be the same ones used in RC= U. > > > > > > > > > > > On the control plane, you need to read this counter > > > > > > > > > > > and poll for the > > > > > > > > > > counter updates. All this is same cost as in RCU. > > > > > > > > > > > > > > > > > > > > Agree. > > > > > > > > > > > > > > > > > > > > > To control the cost, you will have to control the > > > > > > > > > > > rate of quiescent state reporting and might have to > > > > > > > > > > expose this as a configuration parameter. > > > > > > > > > > > > > > > > > > > > > > The other important information you have to consider > > > > > > > > > > > is if the thread is making any blocking calls, which > > > > > > > > > > > may be in some other library. The thread is supposed > > > > > > > > > > > to call rcu_qsbr_thread_offline API before calling a > > > > > > > > > > blocking call. This allows the RCU to know that this > > > > > > > > > > particular thread will not report quiescent state. The > > > > > > > > > > cryptodev library might not have > > > > > > > > that information. > > > > > > > > > > > > > > > > > > > > > > If you want to go ahead with this design, you can > > > > > > > > > > > still use RCU with single thread configuration (like > > > > > > > > > > > you have mentioned > > > > > > > > > > > below) and hide the > > > > > > > > > > details from the application. > > > > > > > > > > > > > > > > > > > > Yes, same thought here - use rcu_qsbr online/offline > > > > > > > > > > for DP part and hide actual sync details inside callbac= k code. > > > > > > > > > We can give it a try. If we can have the performance > > > > > > > > > numbers, we can decide about how to control how often > > > > > > > > > these APIs are called on the data > > > > > > > > plane. > > > > > > > > > > > > > > > > To avoid misunderstanding: I am talking about calling > > > > > > > > online/offline with every > > > > > > > > cryptodev_enqueue() traversal over CB list. > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > That seems quite a big change and I > > > > > > > > > > > > > > > > > > don't think it is acceptable for most u= sers. > > > > > > > > > > > > > > > > > > From my perspective adding/installing > > > > > > > > > > > > > > > > > > call-backs to the dev has to be opaque > > > > > > > > > > > > > > > > > > to the data- > > > > plane code. > > > > > > > > > > > > > > > > > > Also note that different callbacks can > > > > > > > > > > > > > > > > > > be installed by different entities > > > > > > > > > > > > > > > > > > (libs) and might have no idea about > > > > > > > > > > > > > > > > > > each > > > > > > > > > > other. > > > > > > > > > > > > > > > > > > That's why I thought it would be > > > > > > > > > > > > > > > > > > better to make all this RCU stuff inter= nal inside > cryptodev: > > > > > > > > > > > > > > > > > > hide all this rcu_qsbr > > > > > > > > > > > > > > > > > > allocation/setup inside cryptod > > > > > > > > > > > > > > > > > > somehow to > > > > > > > > > > > > > > > > obtain pointer to that rcu_qsbr ev > > > > > > > > > > > > > > > > init/queue setup > > > > > > > > > > > > > > > > > > invoke > > > > > > > > > > > > > > > > > > rcu_qsbr_online()/rcu_qsbr_offline() > > > > > > > > > > > > > > > > > > inside > > > > > > > > > > > > > > > > cryptodev_enqueue(). > > > > > > > > > > > > > This will bring in the application related > > > > > > > > > > > > > information such as the thread ID > > > > > > > > > > > > into the library. > > > > > > > > > > > > > > > > > > > > > > > > I don't think it would. > > > > > > > > > > > > Cryptodev enqueue/dequeue functions are not > > > > > > > > > > > > supposed to be thread safe (same as rx/tx burst). > > > > > > > > > > > > So we can always use RCU with just one thread(threa= d_id =3D > 0). > > > > > > > > > > > Agree, the memory that needs to be freed is accessed > > > > > > > > > > > by a single thread > > > > > > > > > > on the data plane. RCU with one thread would suffice. > > > > > > > > > > > > > > > > > > > > > > > But as I said above - if you feel RCU lib is an > > > > > > > > > > > > overhead here, that's fine - I think it would be > > > > > > > > > > > > easy enough to do without > > > > > > librte_rcu. > > > > > > > > > > > > > > > > > > > > > > > > > If the same API calls are being made from > > > > > > > > > > > > > multiple data plane threads, you need a way to > > > > > > > > > > > > > configure that information to the library. So, > > > > > > > > > > > > > it is better to leave those details for the > > > > > > > > > > > > > application to > > > > > > > > handle. > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > I have already tried exploring above stuf= fs. > > > > > > > > > > > > > > > > > There are too many > > > > > > > > > > > > > > constraints. > > > > > > > > > > > > > > > > > The changes don't fit in, as per RCU desi= gn. > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > Hmm could you be more specific here - what > > > > > > > > > > > > > > > > constraints are you referring to? > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > Moreover, having rcu api under > > > > > > > > > > > > > > > > > enqueue_burst() will affect the > > > > > > > > > > > > > > > > performance. > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > It most likely will. Though my expectation > > > > > > > > > > > > > > > > it will affect performance only when some > > > > > > > > > > > > > > > > callbacks are installed. My thought > > > > > > > > > > > > here: > > > > > > > > > > > > > > > > callback function by itself will affect > > > > > > > > > > > > > > > > cryptdev_enqueue performance anyway, > > > > > > > > > > > > > > > With existing callback design, I have > > > > > > > > > > > > > > > measured the performance(with > > > > > > > > > > > > > > crypto perf test) on xeon. > > > > > > > > > > > > > > > It was almost negligible and same was shared > > > > > > > > > > > > > > > with > > Declan. > > > > > > > > > > > > > > > > > > > > > > > > > > > > I am asking about different thing: did you try > > > > > > > > > > > > > > alternate approach I described, that wouldn't > > > > > > > > > > > > > > require changes in the user data- > > > > > > > > > > plane code. > > > > > > > > > > > > > > > > > > > > > > > > > > > > > That is one of the reasons, I didn't want to > > > > > > > > > > > > > > > add to many stuffs in to the > > > > > > > > > > > > > > callback. > > > > > > > > > > > > > > > The best part of existing design is crypto > > > > > > > > > > > > > > > lib is not much > > > > > > modified. > > > > > > > > > > > > > > > The changes are either pushed to CP or DP. > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > so adding extra overhead for sync is probably= ok > here. > > > > > > > > > > > > > > > > > > > > > > > > > > > > I think that extra overhead when callbacks are > > > > > > > > > > > > > > present is expected and probably acceptable. > > > > > > > > > > > > > > Changes in the upper-layer data-plane code - pr= obably > not. > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > Though for situation when no callbacks are > > > > > > > > > > > > > > > > installed > > > > > > > > > > > > > > > > - perfomance should be left unaffected (or > > > > > > > > > > > > > > > > impact should be as small > > > > > > > > > > > > as possible). > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > The changes are more on control plane > > > > > > > > > > > > > > > > > side, which is one > > > > > > > > time. > > > > > > > > > > > > > > > > > The data plane changes are minimal. > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > I still think upper layer data-plane code > > > > > > > > > > > > > > > > should stay unaffected (zero changes). > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > >