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1696c75f18
This patch changes the time when we sending an ack back to tell the other side it can free some message because it is arrived on the receiver node, due random reconnects e.g. TCP resets this is handled as well on application layer to not let DLM run into a deadlock state. The current handling has the following problems: 1. We end in situations that we only send an ack back message of 16 bytes out and no other messages. Whereas DLM has logic to combine so much messages as it can in one send() socket call. This behaviour can be discovered by "trace-cmd start -e dlm_recv" and observing the ret field being 16 bytes. 2. When processing of DLM messages will never end because we receive a lot of messages, we will not send an ack back as it happens when the processing loop ends. This patch introduces a likely and unlikely threshold case. The likely case will send an ack back on a transmit path if the threshold is triggered of amount of processed upper layer protocol. This will solve issue 1 because it will be send when another normal DLM message will be sent. It solves issue 2 because it is not part of the processing loop. There is however a unlikely case, the unlikely case has a bigger threshold and will be triggered when we only receive messages and do not sent any message back. This case avoids that the sending node will keep a lot of message for a long time as we send sometimes ack backs to tell the sender to finally release messages. The atomic cmpxchg() is there to provide a atomically ack send with reset of the upper layer protocol delivery counter. Signed-off-by: Alexander Aring <aahringo@redhat.com> Signed-off-by: David Teigland <teigland@redhat.com> |
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Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.