Ccache on btrfs

Ccache on btrfs

[Leonidas Spyropoulos]

Hi 

Is there an issue with btrfs ccache and multiple threads during compilation? I'm experiencing kernel panics while building Linux kernel on a btrfs system with -j8 and ccache enabled. Google suggest there was some issue on earlier kernels but my kernel is 3.16+

Anyone can confirm? 

Thanks 
Leonidas 

Re: Ccache on btrfs

[Leonidas Spyropoulos]

On 17/10/14, Timofey Titovets wrote:
> i use ccache and often compile linux from git,
> I don't catch any errors with it.
> 
Interesting, I re-enabled ccache on an ext4 partition (HDD) and worked
fine. So I suspect it's something to do with btrfs and SSD. My mount
options are:
/dev/sda3 on /home type btrfs (rw,relatime,ssd,discard,nospace_cache)

The problem is that I can't get hold of kernel panic since it's not in
the journal [1]. I don't know a way to get hold of the kernel panic log
to help anyway.

What would it be useful to debug it?

[1] using systemd

Leonidas

Re: Ccache on btrfs

[Josef Bacik]

On 10/17/2014 03:24 PM, Leonidas Spyropoulos wrote:
> On 17/10/14, Timofey Titovets wrote:
>> i use ccache and often compile linux from git,
>> I don't catch any errors with it.
>>
> Interesting, I re-enabled ccache on an ext4 partition (HDD) and worked
> fine. So I suspect it's something to do with btrfs and SSD. My mount
> options are:
> /dev/sda3 on /home type btrfs (rw,relatime,ssd,discard,nospace_cache)
>
> The problem is that I can't get hold of kernel panic since it's not in
> the journal [1]. I don't know a way to get hold of the kernel panic log
> to help anyway.
>
> What would it be useful to debug it?

Setup netconsole, you can set it to go to a different box and then on 
that box run

nc -lu -p 514 > out.txt

and then reproduce the panic.  If you are using fedora you can install 
netconsole and edit /etc/sysconfig/netconsole and set SYSLOGADDR=<your 
other boxes address>.  Thanks,

Josef