And to answer biffer question, buffer memory is allocated by vpp. — Damjan
> On Feb 1, 2019, at 3:51 PM, Dave Barach via Lists.Fd.Io > <dbarach=cisco....@lists.fd.io> wrote: > > Next frames are the physical manifestations of graph arcs. Pending frames are > graph scheduler run-queue entries. > > -----Original Message----- > From: vpp-dev@lists.fd.io <vpp-dev@lists.fd.io> On Behalf Of Raj > Sent: Friday, February 1, 2019 9:47 AM > To: vpp-dev <vpp-dev@lists.fd.io> > Subject: Re: [vpp-dev] Understanding vlib_frame_t > > Thanks Damjan and Dave. These small explanations will greatly help in making > sure what I understand from reading code is correct. > > Just a couple of followup questions, I hope these will help those reading the > archives later too in understanding the nuances of VPP architecture. > > vlib_get_buffer() translates the buffer index into buffer pointer. > Where exactly is the buffer memory getting allocated, when packets are coming > in via dpdk-input? Is this allocation is done by DPDK or this is done by VPP. > If I understand correctly vlib_buffer_t is pointing to this location. > > Also as I understand, a graph nodes gets a vector. This vector is a frame > which holds a set of 4 Byte buffer indices which points to the the actual > buffer, containing packets. Node process all these packets (max 256) and > transmit to the next node. While reading code in this area, after processing > this there is reference to next frame and pending frame. I could not figure > out what these are and for what they are being used. > > Thanks and Regards, > > Raj > >> On Thu, Jan 31, 2019 at 9:31 PM Dave Barach (dbarach) <dbar...@cisco.com> >> wrote: >> >> In vlib – vpp’s basic vector library - frames comprise a single vector, a >> set of scalar variables, and some flags. >> >> >> >> At node creation time, each graph node registration indicates the size of a >> vector element, and the total size of scalar data. Vlib_frame_t vectors >> include up to VLIB_FRAME_SIZE (256) vector elements of the indicated size. >> >> >> >> In the vpp/vnet use case, vector elements are 32-bit buffer handles, easily >> converted to vlib_buffer_t pointers. Most graph nodes do not use scalar data. >> >> >> >> An sample use case for per-frame scalar data: send all these packets in the >> vector to a certain ip address, where the ip address could be stored in 4 or >> 16 octets’ worth of scalar data. >> >> >> >> HTH... Dave >> >> >> >> -----Original Message----- >> From: vpp-dev@lists.fd.io <vpp-dev@lists.fd.io> On Behalf Of Raj >> Sent: Thursday, January 31, 2019 9:27 AM >> To: vpp-dev <vpp-dev@lists.fd.io> >> Subject: [vpp-dev] Understanding vlib_frame_t >> >> >> >> Hello all, >> >> >> >> Continuing my reading of VPP code, I have a query regarding packet handling. >> >> >> >> When a node gets a vector of packets to process, if I understand correctly, >> this would be a vlib_frame_t instance. From this vlib_frame_t instance >> arguments[0] is the offset to first packet, arguments[1] is the offset to >> second packet and so on, upto xx number of packets. Is this understanding >> correct? if yes, how much is the maximum size of the packet buffer? >> >> >> >> Also what is the significance of scalar_size/vector_size in vlib_frame_t? >> Does it mean the number of frames/size of frames? >> >> >> >> in vlib/main.c there is a statement vec_resize (nm->pending_frames, 32). In >> here, what is pending_frames and what is the significance of number 32? >> >> >> >> I know I have been asking too many questions over here and very grateful to >> all who answer. >> >> >> >> Thanks a lot! >> >> >> >> Raj > -=-=-=-=-=-=-=-=-=-=-=- > Links: You receive all messages sent to this group. > > View/Reply Online (#12128): https://lists.fd.io/g/vpp-dev/message/12128 > Mute This Topic: https://lists.fd.io/mt/29606187/675642 > Group Owner: vpp-dev+ow...@lists.fd.io > Unsubscribe: https://lists.fd.io/g/vpp-dev/unsub [dmar...@me.com] > -=-=-=-=-=-=-=-=-=-=-=-
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