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The design of preemptible read-copy-update

The design of preemptible read-copy-update

Posted Oct 11, 2007 12:00 UTC (Thu) by i3839 (guest, #31386)
Parent article: The design of preemptible read-copy-update

Good and very detailed article.

Are there any benchmarks which show how it compares to normal RCU?


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The design of preemptible read-copy-update

Posted Oct 11, 2007 23:50 UTC (Thu) by PaulMcKenney (subscriber, #9624) [Link]

On the read side, the new CONFIG_PREEMPT_RT implementation is about double the overhead of the CONFIG_PREEMPT variant of RCU. Of course your mileage will vary depending on your hardware -- this is on a recent Opteron.

The benchmarks for grace-period latency are obsolete, since they used four (rather than two) stages of grace-period processing. And of course, kudos to Steve Rostedt for convincing me to check whether four stages was really required!

This update-side latency can be avoided by using call_rcu() rather that synchronize_rcu(), but synchronize_rcu() is still preferable in most cases due to its simplicity and ease of use.


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