Re: New experimental btrfs branch ready for testing

Chris Mason
2009-06-05T14:20:08Z

On Thu, Jun 04, 2009 at 02:02:20PM -0500, Steven Pratt wrote:
> Chris Mason wrote:
>> Hello everyone,
>>
>> Yan Zheng has been doing some major surgery to the back references and
>> extent allocation code, tackling bottlenecks in the code that tracks
>> extents. It scales better with many snapshots and performs better in
>> the common case of no snapshots at all.
>>
>> THE NEW CODE IS A FORWARD ROLLING DISK FORMAT CHANGE. This means it is
>> compatible with the current btrfs disk format, but once you mount a
>> filesystem with the new code, it WILL NO LONGER BE MOUNTABLE FROM OLD
>> KERNELS. Old kernels spit out an error message when you try them on new
>> format filesystems.
>>
>> This is a large change, and I'm hoping to have it stable in time for the
>> 2.6.31 merge window. I've been testing it for about a week now, and
>> haven't been able to cause major problems yet. But, testing the
>> compatibility with old format filesystems is the hard part, and
>> everyone that pulls the new code should backup their data first.
>>
>> I've setup git branches called newformat where you can pull the new code.
>>
>> For the kernel (based on 2.6.30-rc7):
>>
>> git pull git://git.kernel.org/pub/scm/linux/kernel/git/mason/btrfs-unstable.git newformat
>>
>>
> So I started the performance runs on this. The base tests completed fine
> on the raid system and I will post results as soon as I can finish
> postprocessing, but when I tried to do nodatacow that machine it crashed
> pretty early. Here is console log:

Hi Steve,

Thanks again for hammering on these. Yan Zheng and I have both been
trying to reproduce problems with nodatacow and with the database random
write run.

But, so far we haven't been able to trigger any crashes. Do you see
anything in your config or setup that is unusual?

-chris