On 2019/1/16 上午8:31, Qu Wenruo wrote:
> 
> 
> On 2019/1/16 上午1:26, Josef Bacik wrote:
>> On Tue, Jan 15, 2019 at 04:15:57PM +0800, Qu Wenruo wrote:
>>> This patchset can be fetched from github:
>>> https://github.com/adam900710/linux/tree/qgroup_delayed_subtree
>>>
>>> Which is based on v5.0-rc1.
>>>
>>
>> I've been testing these patches hoping to get rid of the qgroup deadlock that
>> these patches are supposed to fix, but instead they make the box completely
>> unusable with 100% cpu usage for minutes at a time at every transaction commit.
> 
> I'm afraid it's related to the v5.0-rc1 base, not the patchset itself.
> 
> Just try to balance metadata with 16 snapshots, you'll see btrfs bumping
> its generation like crazy, no matter if quota is enabled or not.
> 
> And since btrfs is committing transaction like crazy, no wonder it will
> do tons of qgroup accounting.
> 
> My bisect leads to commit 64403612b73a94bc7b02cf8ca126e3b8ced6e921
> btrfs: rework btrfs_check_space_for_delayed_refs.

Furthermore, you could try this RFC test case to see the problem.
https://patchwork.kernel.org/patch/10761715/

It would only take around 100s for v4.20 but over 500 for v5.0-rc1 with
tons of unnecessary transaction committed for nothing, no quota enabled.

So I'm afraid that commit is blocking my qgroup patchset.

Thanks,
Qu


> 
> Thanks,
> Qu
> 
>> Thanks,
>>
>> Josef
>>
>