> -----Original Message----- > From: Verma, Shally [mailto:[email protected]] > Sent: Thursday, March 15, 2018 4:12 AM > To: Ahmed Mansour <[email protected]>; Trahe, Fiona > <[email protected]>; [email protected] > Cc: De Lara Guarch, Pablo <[email protected]>; Athreya, Narayana > Prasad > <[email protected]>; Gupta, Ashish <[email protected]>; > Sahu, Sunila > <[email protected]>; Challa, Mahipal <[email protected]>; Jain, > Deepak K > <[email protected]>; Hemant Agrawal <[email protected]>; Roy Pledge > <[email protected]>; Youri Querry <[email protected]>; Daly, Lee > <[email protected]>; > Jozwiak, TomaszX <[email protected]>; Alok Makhariya > <[email protected]>; Shreyansh > Jain <[email protected]> > Subject: RE: [dpdk-dev] [PATCH] compressdev: implement API - mbuf alternative > > @Trahe, Fiona>> We're proposing, in the interest of getting the API out in > 18.05, to stick with mbufs - > acknowledging > >> that they're not optimal for storage and we may propose changes in 18.08. > [Shally] Sounds good to us too. > > @Ahmed Mansour . I am assuming that transferring from mbuf to regular buffers > and back does > >not involve some time consuming work like data copying and such. > [Shally] I too assume copying shouldn't be a need and a big no-no. We > normally extract and pass buf_addr > from mbuf as it is to HW. > So implicit assumption is data memory is dma-able to device. [Fiona] agreed
> > Thanks > Shally > > >-----Original Message----- > >From: Ahmed Mansour [mailto:[email protected]] > >Sent: 15 March 2018 00:32 > >To: Trahe, Fiona <[email protected]>; Verma, Shally > ><[email protected]>; [email protected] > >Cc: De Lara Guarch, Pablo <[email protected]>; Athreya, > >Narayana Prasad > <[email protected]>; > >Gupta, Ashish <[email protected]>; Sahu, Sunila > ><[email protected]>; Challa, Mahipal > ><[email protected]>; Jain, Deepak K <[email protected]>; > >Hemant Agrawal > <[email protected]>; Roy > >Pledge <[email protected]>; Youri Querry <[email protected]>; Daly, Lee > <[email protected]>; Jozwiak, TomaszX > ><[email protected]>; Alok Makhariya <[email protected]>; > >Shreyansh Jain > <[email protected]> > >Subject: Re: [dpdk-dev] [PATCH] compressdev: implement API - mbuf alternative > > > >Hi All, > > > >Sticking with mbufs until at least 1805 works for us. We also see > >storage as the main use case, but ipcomp maybe an important customer use > >case in the future. Nonetheless, I see the mbuf formatting as inherently > >external to the compressdev APIs. An application doing ipcomp should > >just do the mbuf packaging outside of compressdev. At least that is what > >current software implementation of ipcomp do when using zlib.net. I am > >assuming that transferring from mbuf to regular buffers and back does > >not involve some time consuming work like data copying and such. > > > >Thanks, > > > >Ahmed > > > >On 3/14/2018 2:39 PM, Trahe, Fiona wrote: > >> Hi Shally, Ahmed, et al, > >> > >> Following internal and community feedback we've decided that there's still > >> too much churn in this. > >> We're proposing, in the interest of getting the API out in 18.05, to stick > >> with mbufs - acknowledging > >> that they're not optimal for storage and we may propose changes in 18.08. > >> Compressdev will start as an experimental API in 18.05 - we'll POC and > >> benchmark alternatives > >> or API extensions once we get time to do so. > >> > >> Regards, > >> Fiona > >> > >>> -----Original Message----- > >>> From: Verma, Shally [mailto:[email protected]] > >>> Sent: Wednesday, March 14, 2018 12:51 PM > >>> To: Trahe, Fiona <[email protected]>; Ahmed Mansour > >>> <[email protected]>; > [email protected] > >>> Cc: De Lara Guarch, Pablo <[email protected]>; Athreya, > >>> Narayana Prasad > >>> <[email protected]>; Gupta, Ashish > >>> <[email protected]>; Sahu, Sunila > >>> <[email protected]>; Challa, Mahipal <[email protected]>; > >>> Jain, Deepak K > >>> <[email protected]>; Hemant Agrawal <[email protected]>; Roy > >>> Pledge > >>> <[email protected]>; Youri Querry <[email protected]>; Daly, Lee > >>> <[email protected]>; > >>> Jozwiak, TomaszX <[email protected]> > >>> Subject: RE: [dpdk-dev] [PATCH] compressdev: implement API - mbuf > >>> alternative > >>> > >>> > >>> > >>>> -----Original Message----- > >>>> From: Trahe, Fiona [mailto:[email protected]] > >>>> Sent: 13 March 2018 21:22 > >>>> To: Verma, Shally <[email protected]>; Ahmed Mansour > >>>> <[email protected]>; > >>> [email protected] > >>>> Cc: De Lara Guarch, Pablo <[email protected]>; Athreya, > >>>> Narayana Prasad > >>> <[email protected]>; > >>>> Gupta, Ashish <[email protected]>; Sahu, Sunila > >>>> <[email protected]>; Challa, > Mahipal > >>>> <[email protected]>; Jain, Deepak K <[email protected]>; > >>>> Hemant Agrawal > >>> <[email protected]>; Roy > >>>> Pledge <[email protected]>; Youri Querry <[email protected]>; > >>>> Daly, Lee > >>> <[email protected]>; Jozwiak, TomaszX > >>>> <[email protected]>; Trahe, Fiona <[email protected]> > >>>> Subject: RE: [dpdk-dev] [PATCH] compressdev: implement API - mbuf > >>>> alternative > >>>> > >>>> Hi Shally, > >>>> > >>>>> -----Original Message----- > >>>>> From: Verma, Shally [mailto:[email protected]] > >>>>> Sent: Tuesday, March 13, 2018 8:15 AM > >>>>> To: Trahe, Fiona <[email protected]>; Ahmed Mansour > >>>>> <[email protected]>; > >>> [email protected] > >>>>> Cc: De Lara Guarch, Pablo <[email protected]>; Athreya, > >>>>> Narayana Prasad > >>>>> <[email protected]>; Gupta, Ashish > >>>>> <[email protected]>; Sahu, > Sunila > >>>>> <[email protected]>; Challa, Mahipal <[email protected]>; > >>>>> Jain, Deepak K > >>>>> <[email protected]>; Hemant Agrawal <[email protected]>; Roy > >>>>> Pledge > >>>>> <[email protected]>; Youri Querry <[email protected]>; > >>>>> [email protected]; Daly, > Lee > >>>>> <[email protected]>; Jozwiak, TomaszX <[email protected]> > >>>>> Subject: RE: [dpdk-dev] [PATCH] compressdev: implement API - mbuf > >>>>> alternative > >>>>> > >>>>> HI Fiona > >>>>> > >>>>> So I understand we're moving away from mbufs because of its size > >>>>> limitation (64k) and cacheline > >>> overhead > >>>>> and their more suitability to n/w applications. Given that, I > >>>>> understand benefit of having another > >>> structure > >>>>> to input data but then what is proposal for ipcomp like application > >>>>> where mbuf usage may be a > better > >>>>> option? Should we keep support for both (mbuf and this structure) so > >>>>> that apps can use appropriate > >>> data > >>>>> structure depending on their requirement. > >>>> [Fiona] An application can use pass buffers from an mbuf or mbuf chain > >>>> to compressdev by filling in > the > >>>> compressdev struct fields with the mbuf meta-data, using > >>>> rte_pktmbuf_data_len(), > >>>> rte_pktmbuf_mtod(), rte_pktmbuf_mtophys(), etc > >>>> For simplicity I'd prefer to offer only 1 rather than 2 data formats on > >>>> the API. > >>>> We see storage applications rather than IPComp as the main use-case for > >>>> compressdev, so would > prefer > >>>> to optimise for that. > >>>> Do you think otherwise? > >>> [Shally] Yea. We plan to use it for ipcomp and other such possible n/w > >>> apps. So, we envision mbuf > support > >>> as necessary. So, I think we can add two APIs one which process on > >>> rte_comp_op and other on > rte_mbufs > >>> to make it simpler. > >>> > >>>>> Further comments, on github. > >>>>> > >>>>> Thanks > >>>>> Shally > >>>>> > >>>>>> -----Original Message----- > >>>>>> From: Trahe, Fiona [mailto:[email protected]] > >>>>>> Sent: 12 March 2018 21:31 > >>>>>> To: Ahmed Mansour <[email protected]>; Verma, Shally > >>>>>> <[email protected]>; > >>>>> [email protected] > >>>>>> Cc: De Lara Guarch, Pablo <[email protected]>; Athreya, > >>>>>> Narayana Prasad > >>>>> <[email protected]>; > >>>>>> Gupta, Ashish <[email protected]>; Sahu, Sunila > >>>>>> <[email protected]>; Challa, > >>> Mahipal > >>>>>> <[email protected]>; Jain, Deepak K <[email protected]>; > >>>>>> Hemant Agrawal > >>>>> <[email protected]>; Roy > >>>>>> Pledge <[email protected]>; Youri Querry <[email protected]>; > >>>>>> [email protected]; > >>> Daly, > >>>>> Lee <[email protected]>; > >>>>>> Jozwiak, TomaszX <[email protected]> > >>>>>> Subject: RE: [dpdk-dev] [PATCH] compressdev: implement API - mbuf > >>>>>> alternative > >>>>>> > >>>>>> Hi Shally, Ahmed, and anyone else interested in compressdev, > >>>>>> > >>>>>> I mentioned last week that we've been exploring using something other > >>>>>> than mbufs to pass src/dst > >>>>> buffers to compressdev PMDs. > >>>>>> Reasons: > >>>>>> - mbuf data is limited to 64k-1 in each segment of a chained mbuf. > >>>>>> Data for compression > >>>>>> can be greater and it would add cycles to have to break up into > >>>>>> smaller segments. > >>>>>> - data may originate in mbufs, but is more likely, particularly for > >>>>>> storage use-cases, to > >>>>>> originate in other data structures. > >>>>>> - There's a 2 cache-line overhead for every segment in a chain, most > >>>>>> of this data > >>>>>> is network-related, not needed by compressdev > >>>>>> So moving to a custom structure would minimise memory overhead, remove > >>>>>> restriction on 64k-1 > size > >>> and > >>>>> give more flexibility if > >>>>>> compressdev ever needs any comp-specific meta-data. > >>>>>> > >>>>>> We've come up with a compressdev-specific structure using the struct > >>>>>> iovec from sys/uio.h, which > is > >>>>> commonly used by storage > >>>>>> applications. This would replace the src and dest mbufs in the op. > >>>>>> I'll not include the code here - Pablo will push that to github > >>>>>> shortly and we'd appreciate review > >>>>> comments there. > >>>>>> > https://emea01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2Fpablodelara%2Fd > pdk-draft- > >compressdev&data=02%7C01%7Cahmed.mansour%40nxp.com%7C6a8977f9b3714d58621708d589dae > 567%7C686ea1d3bc2b4c6fa92cd > >99c5c301635%7C0%7C0%7C636566495639618830&sdata=wmFrxeUNyXdxI5%2Fp5gCmyIRfeDnbHebBJ > XbztqdsMrc%3D&reserved=0 > >>>>>> Just posting on the mailing list to give a heads-up and ensure this > >>>>>> reaches a wider audience than > may > >>> see > >>>>> it on github. > >>>>>> Note : We also considered having no data structures in the op, instead > >>>>>> the application > >>>>>> would supply a callback which the PMD would use to retrieve meta-data > >>>>>> (virt address, iova, length) > >>>>>> for each next segment as needed. While this is quite flexible and > >>>>>> allow the application > >>>>>> to keep its data in its native structures, it's likely to cost more > >>>>>> cycles. > >>>>>> So we're not proposing this at the moment, but hope to benchmark it > >>>>>> later while the API is still > >>>>> experimental. > >>>>>> General feedback on direction is welcome here on the mailing list. > >>>>>> For feedback on the details of implementation we would appreciate > >>>>>> comments on github. > >>>>>> > >>>>>> Regards, > >>>>>> Fiona. > >
