[Ndn-interest] [EXT] content store

marwa kareem m.kareem1305 at coeng.uobaghdad.edu.iq
Tue Feb 23 03:24:55 PST 2021

Hi Junxiao,
Thank you for the explanation, now things become more clear to me.

Can you please refer to where buffers are handled in the  nfd and nfd- dpdk
source code?


On Tue, Feb 23, 2021 at 6:33 AM Junxiao Shi <shijunxiao at email.arizona.edu>

> Hi Marwa
>> 1- In the content store you are using skip lists and hash tables in older
>> versions 0.7.x, is the skip lists and hash tables have the ability to store
>> the data packets?
>> because in the repository the btrees have been used, why? I,m confused
>> about this point.
> Typically the Content Store has an *index* pointing to packet buffers.
> When someone says the CS is a hash table, tree, trie, skip list, etc, it
> refers to the structure of the index.
> The packets themselves are stored in buffers elsewhere.
> In NFD, buffers are allocated via malloc; in NDN-DPDK, buffers are fetched
> from a pre-allocated mempool; I don't know how ccnd handles buffers.
> 2- why the number of contents have been used to measure the capacity of
>> the content store and not something like (200MB, 300MB, ...)?
> As I described above, a forwarder stores packets in buffers.
> In both NFD and NDN-DPDK, a buffer is allocated before receiving the
> packet from a socket or Ethernet adapter, and the packet stays in the same
> buffer until it's evicted / deleted.
> Since the packet length is unknown before receiving, every buffer must be
> able to accommodate the maximum packet length (around 9KB).
> As such, the CS capacity in bytes equals the CS capacity in packets
> multiplied by the maximum packet length.
> It has nothing to do with the actual packet length.
> In this case, it's easier to measure CS capacity in packets.
> Yours, Junxiao
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