Delayed ACK alongside DHCP failover

[Terry Burton]

Hi,

An ISC DHCP IO performance article [1] recommends considering the
delayed ACK feature prior to the sledgehammer approach of
dont-use-fsync.

My reading of the archives turns up historical (2011) reports of
problems relating to the use of the delayed ACK feature alongside DHCP
failover. Around this time I see that the feature was compiled out by
default and I do not see a lot of evidence that delayed ACK has
received much attention since that time.

Most distributions do not build with "--enable-delayed-ack" presumably
because the runtime default is to enable the feature in the absence of
any configuration file directives.

Are people successfully using delayed ACK alongside DHCP failover in
production environments? If it is still problematic then perhaps the
performance article [1] should be updated with this caveat.


[1] https://deepthought.isc.org/article/AA-00373/0/Synchronous-Disk-Writes-and-DHCP-Performance-Limitations.html


Thanks,

Terry