[lwip-devel] [patch #9628] loopif: only schedule poll when first packet is enqueued

[Joel Cunningham]

URL:
  <http://savannah.nongnu.org/patch/?9628>

                 Summary: loopif: only schedule poll when first packet is
enqueued
                 Project: lwIP - A Lightweight TCP/IP stack
            Submitted by: jcunningham
            Submitted on: Fri 27 Apr 2018 10:51:27 PM UTC
                Category: Network drivers
                Priority: 5 - Normal
                  Status: None
                 Privacy: Public
             Assigned to: jcunningham
        Originator Email: 
             Open/Closed: Open
         Discussion Lock: Any
         Planned Release: None

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Details:

RFC on attached patch that optimizes the netif_loop_output to only schedule a
call to poll when the first packet is enqueued.  This ensures netif_poll is
ran once per burst of packets that are sent (which is typical in a TCP
transfer).

The old behavior scheduled a call to poll for every packet that was enqueued
and this lead to exhaustion of the MEMP_TCPIP_MSG_API memory pool and
tcpip_mbox (if port is using static mbox size). The extra callbacks are wasted
work because netif_poll drains the entire queue when ran.

This issue presented itself when large TCP transfer go across the loopback
netif.





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File Attachments:


-------------------------------------------------------
Date: Fri 27 Apr 2018 10:51:27 PM UTC  Name:
0001-loopif-only-schedule-poll-when-first-packet-is-enque.patch  Size: 2KiB  
By: jcunningham

<http://savannah.nongnu.org/patch/download.php?file_id=44050>

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