Re: [net-next PATCH 0/4] Documenting eBPF - extended Berkeley Packet Filter

2017-02-08 Thread Jesper Dangaard Brouer 
On Tue, 7 Feb 2017 14:23:23 -0700
Jonathan Corbet  wrote:

> On Tue, 7 Feb 2017 21:51:49 +0100
> Jesper Dangaard Brouer  wrote:
> 
> > I sounds like Daniel (see other email) have bigger plans for what
> > Documentation/BPF/ should contain.  E.g. consolidating
> > Documentation/networking/filter.txt which covers the cBPF/eBPF internals.
> > If that is the case (and I like the idea), then it goes beyond a
> > "userspace-guide".  And perhaps "BPF" is a "book" of its own?  
> 
> One of the real problems with the kernel's documentation is that there is
> really almost no thought given to who the audience is.  We have docs for
> kernel developers, for system admins, for user-space developers, etc., and
> it's all mixed up into one big jumble.
> 
> An objective of mine in launching into this whole project is to try to fix
> that, so that people can readily find the documentation they need.  So I
> don't think a single top-level directory, with a mix of user-space API
> info and "internals", is the right direction to go.  The internals docs
> should, IMO, go elsewhere, probably in the core-api manual.
> 
> See what I'm getting at here?

First I was reluctant (as it would be "easier" just to cramp every eBPF
thing into one directory).  Thinking more about, I agree with you, and
I like your vision.  Focus on the target audience and avoid mixing
different target audience in the same document/book is the way forward.

My audience and objective is helping developers getting started using
eBPF, not core-developers on eBPF (like Daniel).  I do see that, if we
start mixing in too much "internals" then we loose sense of the
original target audience, and then they "exit" as they get "lost" in
details that does not concern them.

Separating BPF docs into different directories (or "books") will make
us think about the target audience.

I would like to propose directory structure:

 Documentation/user-guide/bpf/
 Documentation/core-api/bpf/


> > And it seems Daniel is proposing capital-letters BPF for the directory
> > name "Documentation/BPF/"?  Any opinions on that? (I'm neutral)  
> 
> I think we should paint it green; otherwise I'm not too concerned about
> this particular point...:)

True, bikeshedding...

-- 
Best regards,
  Jesper Dangaard Brouer
  MSc.CS, Principal Kernel Engineer at Red Hat
  LinkedIn: http://www.linkedin.com/in/brouer

Re: [net-next PATCH 0/4] Documenting eBPF - extended Berkeley Packet Filter

2017-02-07 Thread Daniel Borkmann 

On 02/07/2017 10:19 PM, Jesper Dangaard Brouer wrote:

On Tue, 07 Feb 2017 17:43:38 +0100
Daniel Borkmann  wrote:


Hi Jesper,

On 02/07/2017 03:30 PM, Jesper Dangaard Brouer wrote:

Question: What kernel tree should this go into???

If going through Jonathan Corbet, will it appear sooner here???
   https://www.kernel.org/doc/html/latest/
If it will not appear sooner that way, then it's likely best to keep
it in sync with the tree that takes eBPF code changes.


For initial parts, I don't have a preference (Jonathan has though,
so seems fine via docs tree then). If at some /later/ point in time
features come in along with doc updates (similar to test case updates),
probably best to route them via net-next.


This marks the beginning of user-facing developer documentation for
using eBPF (extended Berkeley Packet Filter) as part of the kernel
Documentation/ tree.

This documentation is also available here[1], as an intermidiate quick
way of prototyping and releasing the documentation.  The autoriative
and official version of the documentation is what gets included in the
kernel tree.  The docs at [2] will get updated based on what gets
accepted after the standard peer-review kernel process.


Thanks for your effort of writing a doc. Some high-level comments on
the set from my PoV first.

I think it's definitely the right direction to move everything BPF
related to Documentation/BPF/. Right now, there are a lot of different
places with different kind of documentation, f.e.:


Agree that we need some in-kernel place to centralize bpf related
documentation, as it is too scattered at the moment.


* Documentation/networking/filter.txt
Covers some cBPF/eBPF internals, tooling, etc; mostly technical,
historically the central spot for BPF documentation. "filter" in
filter.txt is long obsolete name, but looks like various sites,
talks, blogs, etc still link to it. (At best, we should keep the
file saying that the doc moved to Documentation/BPF/.)


Agree.


* bpf(2) man page
Has a good start, but right now is heavily behind the current user
facing kernel code.


Yes, the man-page have proven to get out-of-sync.  This is one of the
reasons I prefer this in-kernel-tree documentation, as documentation
can follow the patchset submission, instead of being something
developers need to submit _after_ patches are accepted.



* include/uapi/linux/bpf.h
Mostly relevant for helper function API description.

* netdev conference slides/proceedings
Also contain mostly technical details on eBPF.

* https://github.com/iovisor/bpf-docs
Non-exhaustive collection of various talks from different confs.

* https://qmonnet.github.io/whirl-offload/2016/09/01/dive-into-bpf/
Even bigger and more complete list of documentation material.

* Various lwn articles ;), blog posts (f.e. from Brendan), etc.

Now, challenge is to bring the relevant parts together and logically
separated into Documentation/BPF/ and bpf(2) man page. I think everything
user API relevant would help most if it updates bpf(2) man page. That can
be explanation of different map types, interaction with maps, quirks, etc.


Sorry, but I disagree.  The man-page bpf(2) should only describe the
bpf syscall.  Details on map types should be documented in this
documentation.  Why, because this allow us to enforce documentation
of a new map type is included together with the code submission (else
it will never get documented).


But essential part of the syscall is to create new maps, interact with
them, etc so it's definitely relevant for the man page. The man page
has a couple of FIXMEs in its source that Michael Kerrisk added in the
course of reviewing and editing patches that were submitted; to give
one example related to this:

  [...]
  Currently, the following values are supported for
  .IR map_type :

  .in +4n
  .nf
  enum bpf_map_type {
BPF_MAP_TYPE_UNSPEC,  /* Reserve 0 as invalid map type */
BPF_MAP_TYPE_HASH,
BPF_MAP_TYPE_ARRAY,
BPF_MAP_TYPE_PROG_ARRAY,
  };
  .fi
  .in

  .I map_type
selects one of the available map implementations in the kernel.
  .\" FIXME We need an explanation of why one might choose each of
  .\" these map implementations
  [...]

Thus, I think it makes sense to address these points there instead of
duplicating as a programmer guide in the kernel tree. Maps are not
added as frequently as helper calls, and neither require writing long
novels to document, so we could require submitters to send a patch there.
When it comes to deeper kernel internals that would not be appropriate
in man pages project, but need to be documented nevertheless (perhaps
a guide on what is necessary to implement new map types), they could
then go to the kernel documentation.

What I'm trying to say is that it makes sense to logically defragment
these bits that are relevant for man-page (since user/prog developer
specific) and for kernel doc tree (rather kernel developer specific),
so

Re: [net-next PATCH 0/4] Documenting eBPF - extended Berkeley Packet Filter

2017-02-07 Thread Jonathan Corbet 
On Tue, 7 Feb 2017 21:51:49 +0100
Jesper Dangaard Brouer  wrote:

> I sounds like Daniel (see other email) have bigger plans for what
> Documentation/BPF/ should contain.  E.g. consolidating
> Documentation/networking/filter.txt which covers the cBPF/eBPF internals.
> If that is the case (and I like the idea), then it goes beyond a
> "userspace-guide".  And perhaps "BPF" is a "book" of its own?

One of the real problems with the kernel's documentation is that there is
really almost no thought given to who the audience is.  We have docs for
kernel developers, for system admins, for user-space developers, etc., and
it's all mixed up into one big jumble.

An objective of mine in launching into this whole project is to try to fix
that, so that people can readily find the documentation they need.  So I
don't think a single top-level directory, with a mix of user-space API
info and "internals", is the right direction to go.  The internals docs
should, IMO, go elsewhere, probably in the core-api manual.

See what I'm getting at here?

> And it seems Daniel is proposing capital-letters BPF for the directory
> name "Documentation/BPF/"?  Any opinions on that? (I'm neutral)

I think we should paint it green; otherwise I'm not too concerned about
this particular point...:)

Thanks,

jon

Re: [net-next PATCH 0/4] Documenting eBPF - extended Berkeley Packet Filter

2017-02-07 Thread Jesper Dangaard Brouer 
On Tue, 07 Feb 2017 17:43:38 +0100
Daniel Borkmann  wrote:

> Hi Jesper,
> 
> On 02/07/2017 03:30 PM, Jesper Dangaard Brouer wrote:
> > Question: What kernel tree should this go into???
> >
> > If going through Jonathan Corbet, will it appear sooner here???
> >   https://www.kernel.org/doc/html/latest/
> > If it will not appear sooner that way, then it's likely best to keep
> > it in sync with the tree that takes eBPF code changes.  
> 
> For initial parts, I don't have a preference (Jonathan has though,
> so seems fine via docs tree then). If at some /later/ point in time
> features come in along with doc updates (similar to test case updates),
> probably best to route them via net-next.
> 
> > This marks the beginning of user-facing developer documentation for
> > using eBPF (extended Berkeley Packet Filter) as part of the kernel
> > Documentation/ tree.
> >
> > This documentation is also available here[1], as an intermidiate quick
> > way of prototyping and releasing the documentation.  The autoriative
> > and official version of the documentation is what gets included in the
> > kernel tree.  The docs at [2] will get updated based on what gets
> > accepted after the standard peer-review kernel process.  
> 
> Thanks for your effort of writing a doc. Some high-level comments on
> the set from my PoV first.
> 
> I think it's definitely the right direction to move everything BPF
> related to Documentation/BPF/. Right now, there are a lot of different
> places with different kind of documentation, f.e.:

Agree that we need some in-kernel place to centralize bpf related
documentation, as it is too scattered at the moment.

> * Documentation/networking/filter.txt
>Covers some cBPF/eBPF internals, tooling, etc; mostly technical,
>historically the central spot for BPF documentation. "filter" in
>filter.txt is long obsolete name, but looks like various sites,
>talks, blogs, etc still link to it. (At best, we should keep the
>file saying that the doc moved to Documentation/BPF/.)

Agree.
 
> * bpf(2) man page
>Has a good start, but right now is heavily behind the current user
>facing kernel code.

Yes, the man-page have proven to get out-of-sync.  This is one of the
reasons I prefer this in-kernel-tree documentation, as documentation
can follow the patchset submission, instead of being something
developers need to submit _after_ patches are accepted.

 
> * include/uapi/linux/bpf.h
>Mostly relevant for helper function API description.
> 
> * netdev conference slides/proceedings
>Also contain mostly technical details on eBPF.
> 
> * https://github.com/iovisor/bpf-docs
>Non-exhaustive collection of various talks from different confs.
> 
> * https://qmonnet.github.io/whirl-offload/2016/09/01/dive-into-bpf/
>Even bigger and more complete list of documentation material.
> 
> * Various lwn articles ;), blog posts (f.e. from Brendan), etc.
> 
> Now, challenge is to bring the relevant parts together and logically
> separated into Documentation/BPF/ and bpf(2) man page. I think everything
> user API relevant would help most if it updates bpf(2) man page. That can
> be explanation of different map types, interaction with maps, quirks, etc.

Sorry, but I disagree.  The man-page bpf(2) should only describe the
bpf syscall.  Details on map types should be documented in this
documentation.  Why, because this allow us to enforce documentation
of a new map type is included together with the code submission (else
it will never get documented).


> Eventually also helper functions. Right now they're all documented in
> include/uapi/linux/bpf.h and that's okay as it ships along with the
> kernel code, so they're in sync. Eventually, there should be some more
> elaborate description of them, perhaps with tiny examples, in bpf(2)
> as well, since it's part of the uapi and stable (helpers themselves at
> least).

IMHO descriptions for bpf helpers function does not belong in the
man-page for the bpf(2) syscall.  The bpf helpers are something that
gets used by the ebpf program code which runs kernel side.  (And again
the same argument about introducing new will not get updated in the man
page).


> The Documentation/networking/filter.txt would need to be reworked a
> bit and split into pieces for Documentation/BPF/, so we keep that as a
> central place for the technical parts. Documentation/RCU/ is doing a
> great job at that, and I would like to see Documentation/BPF/ being as
> helpful for developers here. Part of that would be to add missing
> pieces from the various available sources mentioned above or
> elsewhere, so people can get a deeper understanding on internals
> beyond reading just man page for the user API description; explaining
> concepts, etc. Part of that can also be on the ELF loader bits, etc,
> no doubt.

Agree
 
> On a quick glance on the remaining patches, it seems a mixture of
> quotes from the bpf(2) man page, filter.txt along with sample code
>

Re: [net-next PATCH 0/4] Documenting eBPF - extended Berkeley Packet Filter

2017-02-07 Thread Jesper Dangaard Brouer 
On Tue, 7 Feb 2017 09:46:08 -0700
Jonathan Corbet  wrote:

> On Tue, 7 Feb 2017 17:09:08 +0100
> Jesper Dangaard Brouer  wrote:
> 
> > > > Question: What kernel tree should this go into???
> > > > 
> > > > If going through Jonathan Corbet, will it appear sooner here???
> > > >  https://www.kernel.org/doc/html/latest/
> > 
> > What about this question?  Or let me ask in another way, what tree is
> > https://www.kernel.org/doc/html/latest/ based on?  
> 
> I believe it's generated from the current -rc.  If this stuff goes into
> 4.11, it should show up there next week.
> 
> > Yes, I was also wondering hard where to put it... and a book for
> > user-space developer documentation would likely be the right place, but
> > it was not there, as you mention ;-) 
> > 
> > I'm fine with moving it later under another "book". Linking to it as
> > HTML would still be the same right? 
> > (https://www.kernel.org/doc/html/latest/bpf/index.html)
> > And is the Documentation/bpf/ directory the correct place?  
> 
> Moving it would change the URL, of course.  If we want to avoid that, we
> should try to come up with the proper placement from the outset.  And we
> would want to move it; I really want to clean up the mess that is the
> top-level directory.
> 
> How about if it goes into Documentation/userspace-guide/bpf ?  The
> intermediate directory could just be empty for now, I'll put the book
> structure into place later on.  Then the URL for the BPF guide itself
> wouldn't change.

I sounds like Daniel (see other email) have bigger plans for what
Documentation/BPF/ should contain.  E.g. consolidating
Documentation/networking/filter.txt which covers the cBPF/eBPF internals.
If that is the case (and I like the idea), then it goes beyond a
"userspace-guide".  And perhaps "BPF" is a "book" of its own?

And it seems Daniel is proposing capital-letters BPF for the directory
name "Documentation/BPF/"?  Any opinions on that? (I'm neutral)

-- 
Best regards,
  Jesper Dangaard Brouer
  MSc.CS, Principal Kernel Engineer at Red Hat
  LinkedIn: http://www.linkedin.com/in/brouer

Re: [net-next PATCH 0/4] Documenting eBPF - extended Berkeley Packet Filter

2017-02-07 Thread Jonathan Corbet 
On Tue, 7 Feb 2017 17:09:08 +0100
Jesper Dangaard Brouer  wrote:

> > > Question: What kernel tree should this go into???
> > > 
> > > If going through Jonathan Corbet, will it appear sooner here???
> > >  https://www.kernel.org/doc/html/latest/  
> 
> What about this question?  Or let me ask in another way, what tree is
> https://www.kernel.org/doc/html/latest/ based on?

I believe it's generated from the current -rc.  If this stuff goes into
4.11, it should show up there next week.

> Yes, I was also wondering hard where to put it... and a book for
> user-space developer documentation would likely be the right place, but
> it was not there, as you mention ;-) 
> 
> I'm fine with moving it later under another "book". Linking to it as
> HTML would still be the same right? 
> (https://www.kernel.org/doc/html/latest/bpf/index.html)
> And is the Documentation/bpf/ directory the correct place?

Moving it would change the URL, of course.  If we want to avoid that, we
should try to come up with the proper placement from the outset.  And we
would want to move it; I really want to clean up the mess that is the
top-level directory.

How about if it goes into Documentation/userspace-guide/bpf ?  The
intermediate directory could just be empty for now, I'll put the book
structure into place later on.  Then the URL for the BPF guide itself
wouldn't change.

jon

Re: [net-next PATCH 0/4] Documenting eBPF - extended Berkeley Packet Filter

2017-02-07 Thread Daniel Borkmann 

Hi Jesper,

On 02/07/2017 03:30 PM, Jesper Dangaard Brouer wrote:

Question: What kernel tree should this go into???

If going through Jonathan Corbet, will it appear sooner here???
  https://www.kernel.org/doc/html/latest/
If it will not appear sooner that way, then it's likely best to keep
it in sync with the tree that takes eBPF code changes.


For initial parts, I don't have a preference (Jonathan has though,
so seems fine via docs tree then). If at some /later/ point in time
features come in along with doc updates (similar to test case updates),
probably best to route them via net-next.


This marks the beginning of user-facing developer documentation for
using eBPF (extended Berkeley Packet Filter) as part of the kernel
Documentation/ tree.

This documentation is also available here[1], as an intermidiate quick
way of prototyping and releasing the documentation.  The autoriative
and official version of the documentation is what gets included in the
kernel tree.  The docs at [2] will get updated based on what gets
accepted after the standard peer-review kernel process.


Thanks for your effort of writing a doc. Some high-level comments on
the set from my PoV first.

I think it's definitely the right direction to move everything BPF
related to Documentation/BPF/. Right now, there are a lot of different
places with different kind of documentation, f.e.:

* Documentation/networking/filter.txt
  Covers some cBPF/eBPF internals, tooling, etc; mostly technical,
  historically the central spot for BPF documentation. "filter" in
  filter.txt is long obsolete name, but looks like various sites,
  talks, blogs, etc still link to it. (At best, we should keep the
  file saying that the doc moved to Documentation/BPF/.)

* bpf(2) man page
  Has a good start, but right now is heavily behind the current user
  facing kernel code.

* include/uapi/linux/bpf.h
  Mostly relevant for helper function API description.

* netdev conference slides/proceedings
  Also contain mostly technical details on eBPF.

* https://github.com/iovisor/bpf-docs
  Non-exhaustive collection of various talks from different confs.

* https://qmonnet.github.io/whirl-offload/2016/09/01/dive-into-bpf/
  Even bigger and more complete list of documentation material.

* Various lwn articles ;), blog posts (f.e. from Brendan), etc.

Now, challenge is to bring the relevant parts together and logically
separated into Documentation/BPF/ and bpf(2) man page. I think everything
user API relevant would help most if it updates bpf(2) man page. That can
be explanation of different map types, interaction with maps, quirks, etc.

Eventually also helper functions. Right now they're all documented in
include/uapi/linux/bpf.h and that's okay as it ships along with the
kernel code, so they're in sync. Eventually, there should be some more
elaborate description of them, perhaps with tiny examples, in bpf(2)
as well, since it's part of the uapi and stable (helpers themselves at
least).

The Documentation/networking/filter.txt would need to be reworked a
bit and split into pieces for Documentation/BPF/, so we keep that as a
central place for the technical parts. Documentation/RCU/ is doing a
great job at that, and I would like to see Documentation/BPF/ being as
helpful for developers here. Part of that would be to add missing pieces
from the various available sources mentioned above or elsewhere, so
people can get a deeper understanding on internals beyond reading just
man page for the user API description; explaining concepts, etc. Part
of that can also be on the ELF loader bits, etc, no doubt.

On a quick glance on the remaining patches, it seems a mixture of quotes
from the bpf(2) man page, filter.txt along with sample code explanation and
lots of external links, part of them to https://git.kernel.org/cgit/linux/...,
http://lxr.free-electrons.com, http://man7.org, http://www.slideshare.net/,
https://github.com/torvalds/linux/..., etc. I would suggest that instead we
should make Documentation/BPF/ eventually as self-contained as possible
and the central place for the internals where others link to instead. It
might take a bit, but I think definitely worth it.

Regarding patches, could you split the parts that should go to bpf(2) off
and submit them to man page tree for inclusion? I think that would be
incredibly helpful. And the remaining internals to start a Documentation/BPF/
directory, even if initially just small (but will grow over time of
course)?

Thanks,
Daniel


[1] http://prototype-kernel.readthedocs.io/en/latest/bpf/index.html
[2] 
https://github.com/netoptimizer/prototype-kernel/tree/master/kernel/Documentation

Thanks to the following people, who have already reviewed and fixed
earlier versions of this documentation on the IOvisor mailing-list:

  Alexander Alemayhu 
  Alexei Starovoitov 
  Daniel Borkmann 
  Quentin Monnet 


---

Jesper Dangaard Brouer (4):

Re: [net-next PATCH 0/4] Documenting eBPF - extended Berkeley Packet Filter

2017-02-07 Thread Jesper Dangaard Brouer 
On Tue, 7 Feb 2017 08:37:17 -0700
Jonathan Corbet  wrote:

> On Tue, 07 Feb 2017 15:30:11 +0100
> Jesper Dangaard Brouer  wrote:
> 
> > Question: What kernel tree should this go into???
> > 
> > If going through Jonathan Corbet, will it appear sooner here???
> >  https://www.kernel.org/doc/html/latest/

What about this question?  Or let me ask in another way, what tree is
https://www.kernel.org/doc/html/latest/ based on?


> > If it will not appear sooner that way, then it's likely best to keep
> > it in sync with the tree that takes eBPF code changes.  
> 
> I've developed a fairly strong preference for carrying patches touching
> index.rst; otherwise I spend a lot of time explaining merge conflicts to
> Linus.
> 
> If the consensus is that this is ready to go, I expect I can squeeze it in
> for 4.11.  I'm not too worried about regressions...:)
> 
> I haven't actually built it yet, but from a first look it seems like an
> awfully good start.  The one thing that comes to mind is that I'm likely
> to want to move it at some point.  I'd really like to start a separate
> book for user-space developer documentation, and this would certainly
> belong there.  That book doesn't exist yet, though, so I can't quite blame
> you, hard as I might try, for not putting this document there.

Yes, I was also wondering hard where to put it... and a book for
user-space developer documentation would likely be the right place, but
it was not there, as you mention ;-) 

I'm fine with moving it later under another "book". Linking to it as
HTML would still be the same right? 
(https://www.kernel.org/doc/html/latest/bpf/index.html)
And is the Documentation/bpf/ directory the correct place?

-- 
Best regards,
  Jesper Dangaard Brouer
  MSc.CS, Principal Kernel Engineer at Red Hat
  LinkedIn: http://www.linkedin.com/in/brouer

Re: [net-next PATCH 0/4] Documenting eBPF - extended Berkeley Packet Filter

2017-02-07 Thread Jonathan Corbet 
On Tue, 07 Feb 2017 15:30:11 +0100
Jesper Dangaard Brouer  wrote:

> Question: What kernel tree should this go into???
> 
> If going through Jonathan Corbet, will it appear sooner here???
>  https://www.kernel.org/doc/html/latest/
> If it will not appear sooner that way, then it's likely best to keep
> it in sync with the tree that takes eBPF code changes.

I've developed a fairly strong preference for carrying patches touching
index.rst; otherwise I spend a lot of time explaining merge conflicts to
Linus.

If the consensus is that this is ready to go, I expect I can squeeze it in
for 4.11.  I'm not too worried about regressions...:)

I haven't actually built it yet, but from a first look it seems like an
awfully good start.  The one thing that comes to mind is that I'm likely
to want to move it at some point.  I'd really like to start a separate
book for user-space developer documentation, and this would certainly
belong there.  That book doesn't exist yet, though, so I can't quite blame
you, hard as I might try, for not putting this document there.

Thanks,

jon

[net-next PATCH 0/4] Documenting eBPF - extended Berkeley Packet Filter

2017-02-07 Thread Jesper Dangaard Brouer 
Question: What kernel tree should this go into???

If going through Jonathan Corbet, will it appear sooner here???
 https://www.kernel.org/doc/html/latest/
If it will not appear sooner that way, then it's likely best to keep
it in sync with the tree that takes eBPF code changes.


This marks the beginning of user-facing developer documentation for
using eBPF (extended Berkeley Packet Filter) as part of the kernel
Documentation/ tree.

This documentation is also available here[1], as an intermidiate quick
way of prototyping and releasing the documentation.  The autoriative
and official version of the documentation is what gets included in the
kernel tree.  The docs at [2] will get updated based on what gets
accepted after the standard peer-review kernel process.

[1] http://prototype-kernel.readthedocs.io/en/latest/bpf/index.html
[2] 
https://github.com/netoptimizer/prototype-kernel/tree/master/kernel/Documentation

Thanks to the following people, who have already reviewed and fixed
earlier versions of this documentation on the IOvisor mailing-list:

 Alexander Alemayhu 
 Alexei Starovoitov 
 Daniel Borkmann 
 Quentin Monnet 


---

Jesper Dangaard Brouer (4):
  doc/bpf: start eBPF documentation tree bpf/
  doc/bpf: document interacting with eBPF maps
  doc/bpf: describes the different types of eBPF maps available
  doc/bpf: describe BCC the BPF Compiler Collection


 Documentation/bpf/bcc_tool_chain.rst  |   37 +
 Documentation/bpf/ebpf_maps.rst   |  256 +
 Documentation/bpf/ebpf_maps_types.rst |  119 +++
 Documentation/bpf/index.rst   |   68 +
 Documentation/index.rst   |1 
 5 files changed, 481 insertions(+)
 create mode 100644 Documentation/bpf/bcc_tool_chain.rst
 create mode 100644 Documentation/bpf/ebpf_maps.rst
 create mode 100644 Documentation/bpf/ebpf_maps_types.rst
 create mode 100644 Documentation/bpf/index.rst

--