Rajasekarr/backpressure bgp zebra #15390
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Currently, the way zebra works is it creates pthread per client (BGP is
of interest in this case) and this thread loops itself in zserv_read()
to check for any incoming data. If there is one, then it reads,
validates and adds it in the ibuf_fifo signalling the main thread to
process the message. The main thread when it gets a change, processes
the message, and invokes the function pointer registered in the header
command. (Ex: zserv_handlers).
Finally, if all of this was successful, this task reschedules itself and
loops in zserv_read() again
However, if there are already items on the ibuf FIFO, that means zebra is
slow in processing. And with the current mechanism if Zebra main is busy,
the ibuf FIFO keeps growing holding up the memory.
Show memory zebra:(Example: 3456 FIFO elements hoarding ~160 MB of data)
--- qmem libfrr ---
Stream : 44 variable 3432352 15042 161243800
Stream FIFO : 45 72 3240 48 3456
Fix:
- Stop doing the read events when we know there are X number of items
on the FIFO already.(X - zebra zapi-packets <1-10000> (Default-1000)
- In zserv_read(), determine the number of items on the zserv->ibuf_fifo.
Subtract this from the work items and only pull the number of items off
that would take us to X items on the ibuf_fifo again.
- If the number of items in the ibuf_fifo has reached to the maximum
* Either initially when zserv_read() is called (or)
* when processing the remainders of the incoming buffer
the zserv_read which runs in client’s pthread expects the zebra main to
schedule a wake up in zserv_process_message after the processing of all
the items on the buffer.
Ticket: #3390099
Signed-off-by: Rajasekar Raja <[email protected]>
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Modify the bgp master to hold a type safe list for bgp_dests that need to be passed to zebra. Future commits will use this. Ticket: #3390099 Signed-off-by: Donald Sharp <[email protected]> Signed-off-by: Rajasekar Raja <[email protected]>
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Since installing/withdrawing routes into zebra is going to be changed around to be dest based in a list, - Retrieve the afi/safi to use based upon the dest's afi/safi instead of passing it in. - Prefix is known by the dest. Remove this arg as well Ticket: #3390099 Signed-off-by: Donald Sharp <[email protected]> Signed-off-by: Rajasekar Raja <[email protected]>
BGP is now keeping a list of dests with the dest having a pointer to the bgp_path_info that it will be working on. 1) When bgp receives a prefix, process it, add the bgp_dest of the prefix into the new Fifo list if not present, update the flags (Ex: earlier if the prefix was advertised and now it is a withdrawn), increment the ref_count and DO NOT advertise the install/withdraw to zebra yet. 2) Schedule an event to wake up to invoke the new function which will walk the list one by one and installs/withdraws the routes into zebra. a) if BUFFER_EMPTY, process the next item on the list b) if BUFFER_PENDING, bail out and the callback in zclient_flush_data() will invoke the same function when BUFFER_EMPTY Changes - rename old bgp_zebra_announce to bgp_zebra_announce_actual - rename old bgp_zebra_withdrw to bgp_zebra_withdraw_actual - Handle new fifo list cleanup in bgp_exit() - New funcs: bgp_handle_route_announcements_to_zebra() and bgp_zebra_route_install() - Define a callback function to invoke bgp_handle_route_announcements_to_zebra() when BUFFER_EMPTY in zclient_flush_data() The current change deals with bgp installing routes via bgp_process_main_one() Ticket: #3390099 Signed-off-by: Donald Sharp <[email protected]> Signed-off-by: Rajasekar Raja <[email protected]>
Current changes deals with EVPN routes installation to zebra. In evpn_route_select_install() we invoke evpn_zebra_install/uninstall which sends zclient_send_message(). Making similar changes as previous commit to handle evpn part of the code. Ticket: #3390099 Signed-off-by: Rajasekar Raja <[email protected]>
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each component will get it's own PR |
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