[Dnsmasq-discuss] dnsmasq using 100% cpu on router

[Simon Kelley]

Note that this bug appears to be a hard lockup.

https://bugs.launchpad.net/ubuntu/+source/dnsmasq/+bug/1313393

investigations are continuing.....


Simon.




On 28/04/14 12:18, Kevin Darbyshire-Bryant wrote:
> On 25/04/2014 09:37, David Joslin wrote:
>> Hi Kevin and thanks for the help.
>>
> Apologies for delay in reply.
>> Is it possible to upgrade the dnsmasq version on the router without
>> waiting for the author of the tomato firmware to include a later
>> version in a release of his firmware (and you mentioned that dnsmasq
>> in tomato isn't a clean pull of Simon's release)?
> Probably, but as you'd have to cross compile it to MIPS and 'Tomato'
> environment you might as well try to rebuild the entire firmware.  I
> loosely 'maintain' a shadow of Simon's git repo of dnsmasq with the
> Tomato/Asuswrt tweaks here
> https://github.com/kdarbyshirebryant/dnsmasq   - No guarantees etc etc,
> but I personally try to keep up to date with both 'Merlin's
> Asuswrt/rmerlin and put current dnsmasq in there too.
>>
>> Why would changing the location of the leasefile to a usb stick make a
>> difference? If the issue, as Simon suggests, is caused by the constant
>> rewriting of the lease database, then wouldn't its current location
>> (which on a router would be RAM) be a faster/better option than a usb
>> stick? Or is there another possible issue here that I've missed?
> Agree, RAM should be faster but there is a finite amount of it and it's
> volatile...I quite like to store the database on something that survives
> reboots.  Also, as tomato is compiled with 'no rtc', the code tries to
> minimise the number of writes to the leasefile on the basis it thinks it
> likely that flash memory is involved, so better to reduce the wear.
>>
>> The only recent change I've made to the router was the addition of a
>> usb stick as the location for the writing of system logs and bandwidth
>> and IP traffic usage logs (so that they weren't lost on a reboot). I
>> had wondered if the cause of the problem was related to the speed of
>> writing this stuff (which obviously includes dnsmasq logging) to the
>> usb stick rather than RAM. That's why I turned off dnsmasq logging at
>> one point but it didn't seem to make any difference.
>>
>> Thanks again for your help and I'll wait for your comments on the above.
> I'm not sure I've helped really.
> 
> Kevin
> 
> 
> 
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