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Message-ID: <51CCA4C2.7050301@hp.com> Date: Thu, 27 Jun 2013 13:46:58 -0700 From: Rick Jones <rick.jones2@...com> To: Shawn Bohrer <sbohrer@...advisors.com> CC: netdev@...r.kernel.org Subject: Re: Understanding lock contention in __udp4_lib_mcast_deliver On 06/27/2013 01:20 PM, Shawn Bohrer wrote: > On Thu, Jun 27, 2013 at 12:58:39PM -0700, Rick Jones wrote: >> Are there other processes showing _raw_spin_lock time? It may be >> more clear to add a --sort symbol,dso or some such to your perf >> report command. Because what you show there suggests less than 1% >> of the active cycles are in _raw_spin_lock. > > You think I'm wasting time going after small potatoes huh? Perhaps. I also find it difficult to see the potatoes' (symbols') big picture in perf's default sorting :) > On a normal system it looks like it is about .12% total which is > indeed small but my thinking was that I should be able to make that > go to 0 easily by ensuring we use unique ports and only have one > socket per multicast addr:port. Now that I've failed at making it go > to 0 I would mostly like to understand what part of my thinking was > flawed. Or perhaps I can make it go to zero if I do ... How do you know that time is actually contention and not simply acquire and release overhead? rick jones -- 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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