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Re: [tor-relays] 0.2.4.17-rc on Pi, a couple weeks on
On Wed, 18 Sep 2013 18:28:18 -0700, Andy Isaacson <adi@xxxxxxxxxxxxx> wrote:
> On Wed, Sep 18, 2013 at 05:43:13PM -0700, Gordon Morehouse wrote:
> > Thanks, Roger. I'm still not sure what finally caused the OOM-killer
> > crash this morning after almost a couple weeks (?) of uptime. I was
> > also seeing additional clock jump messages but didn't have time to
> > diagnose it. The Pi does not have a battery-backed RTC so it requires
> > a clock set at each start, accomplished by 'ntpdate' and kept in time
> > with, in my case, 'openntpd'. But, 'openntpd' wasn't complaining at
> > the time of the clock jumps that were reported by Tor, and AFAIK
> > 'ntpdate' is not scheduled to run periodically, so I don't know what's
> > causing it yet.
>
> The "Your system clock just jumped 100 seconds forward" messages are
> unlikely to be due to NTP. Much more likely the Tor daemon was blocked
> for a significant time period, due to swapping or similar.
I figured it might have been a really bad clock, but that seemed unlikely. I wouldn't remotely be surprised if what you are saying is true as the Pi is pretty memory-constrained. I'll try to correlate/reproduce it.
When the Pi goes to swap, it's getting desperate - it's swapping to a Class 10 microSD card. :/
> What does top show? In particular the "Mem" and "Swap" lines, and the
> process line for the Tor process. Here's a large Xeon server running 4
> Tor daemons:
>
> top - 18:26:40 up 16 days, 18:18, 1 user, load average: 3.79, 3.95, 3.96
> Tasks: 99 total, 4 running, 95 sleeping, 0 stopped, 0 zombie
> Cpu(s): 69.0%us, 5.1%sy, 0.0%ni, 19.4%id, 0.0%wa, 0.0%hi, 6.5%si, 0.0%st
> Mem: 8176824k total, 6361748k used, 1815076k free, 36336k buffers
> Swap: 0k total, 0k used, 0k free, 183736k cached
>
> PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
> 14567 debian-t 20 0 2003m 1.8g 21m R 109 22.7 4477:00 tor
> 30171 debian-t 20 0 2390m 1.8g 20m R 100 23.6 13544:10 tor
> 18891 debian-t 20 0 1800m 1.5g 23m R 86 19.8 3134:31 tor
> 8798 debian-t 20 0 324m 149m 31m S 21 1.9 36:48.05 tor
>
> A similar picture from your RPi might shed some light on the situation.
*Typically,* tor consumes about 25-40% of all available RAM to handle 300-800 circuits and 0.5-2Mbps of traffic (it boots with 485MB physical available after all is said and done). It always seems to get OOM-killed when I'm sleeping.
Best,
-Gordon M.
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