Survey results very helpful, thanks! (was: Re: net.inet.tcp.timer_race: does anyone have a non-zero value?)

Doug Hardie bc979 at
Mon Mar 8 20:13:32 UTC 2010

On 8 March 2010, at 06:53, Robert Watson wrote:

> On Sun, 7 Mar 2010, Robert Watson wrote:
>> If your system shows a non-zero value, please send me a *private e-mail* with the output of that command, plus also the output of "sysctl kern.smp", "uptime", and a brief description of the workload and network interface configuration.  For example: it's a busy 8-core web server with roughly X connections/second, and that has three em network interfaces used to load balance from an upstream source.  IPSEC is used for management purposes (but not bulk traffic), and there's a local MySQL database.
> I've now received a number of reports that confirm our suspicion that the race does occur, albeit very rarely, and particularly on systems with many cores or multiple network interfaces.  Fixing it is definitely on the TODO for 9.0, both to improve our ability to do multiple virtual network stacks, but with an appropriately scalable fix in mind given our improved TCP scalability for 9.0 as well.

I run a number of 4 core systems with em interfaces.  These are production systems that are unmanned and located a long way from me.  Under unusual conditions it can take up to 6 hours to get there.  I have been waiting to switch to 8.0 because of the discussions on the em device and now it sounds like I had better just skip 8.x and wait for 9.  7.2 is working just fine.

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