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Date: Thu, 30 Jul 2009 13:44:21 +0300 From: Luciano Coelho <luciano.coelho@...ia.com> To: netdev@...r.kernel.org CC: tero.kristo@...ia.com Subject: neigh_periodic_timer expires too often Hi, We were making some measurements and trying to figure out which timers in the kernel can be made deferrable so that our device doesn't have to wake up too often. During this investigation, we found out that the neigh_periodic_timer is expiring approximately every 8 seconds, even when we don't have a network connection established. After the connection is established, the timer starts expiring every 2 seconds and continues to expire at this interval after the connection is closed. We have been converting many of the kernel times to deferrable timers. Checking the netdev mailing list archives, I found out that this issue has been discussed in December 2007 [1], but the thread seems to have died out and the proposed patch has never been applied AFAICS. Another proposed solution, which has never been applied either, was to convert this timer from softirq-based to workqueue-based [2]. Would that be any better? So, my question is, does it make sense to make this timer deferrable or use the workqueue instead? Or is there any other better solution to avoid unnecessarily frequent wakeups caused by neigh_periodic_timer? We are using a kernel based on 2.6.28. [1] http://article.gmane.org/gmane.linux.network/81361 [2] http://article.gmane.org/gmane.linux.network/81140 -- Cheers, Luca. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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