btrfs-progs: fix btrfs-qgroup man page as unstable feature
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Message ID 20200124072521.3462-1-anand.jain@oracle.com
State New
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Series
  • btrfs-progs: fix btrfs-qgroup man page as unstable feature
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Commit Message

Anand Jain Jan. 24, 2020, 7:25 a.m. UTC
There are known performance and counting errors for the quota when qgroup is
enabled.

Signed-off-by: Anand Jain <anand.jain@oracle.com>
---
 Documentation/btrfs-qgroup.asciidoc | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

Comments

Qu Wenruo Jan. 24, 2020, 7:28 a.m. UTC | #1
On 2020/1/24 下午3:25, Anand Jain wrote:
> There are known performance and counting errors for the quota when qgroup is
> enabled.

Counting error is a big problem, please report if you found one not
caused by impersistent qgroup status.

For performance, we still have problem, but that should only be snapshot
dropping.
Balance is no longer a big problem.

Personally I think the current man page still stands.

Thanks,
Qu
> 
> Signed-off-by: Anand Jain <anand.jain@oracle.com>
> ---
>  Documentation/btrfs-qgroup.asciidoc | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/Documentation/btrfs-qgroup.asciidoc b/Documentation/btrfs-qgroup.asciidoc
> index 0c9f5940a1d3..2da3d7819ba6 100644
> --- a/Documentation/btrfs-qgroup.asciidoc
> +++ b/Documentation/btrfs-qgroup.asciidoc
> @@ -16,8 +16,7 @@ DESCRIPTION
>  NOTE: To use qgroup you need to enable quota first using *btrfs quota enable*
>  command.
>  
> -WARNING: Qgroup is not stable yet and will impact performance in current mainline
> -kernel (v4.14).
> +WARNING: Qgroup is an unstable feature as of now.
>  
>  QGROUP
>  ------
>
Anand Jain Jan. 24, 2020, 8:46 a.m. UTC | #2
On 24/1/20 3:28 PM, Qu Wenruo wrote:
> 
> 
> On 2020/1/24 下午3:25, Anand Jain wrote:
>> There are known performance and counting errors for the quota when qgroup is
>> enabled.
> 
> Counting error is a big problem, please report if you found one not
> caused by impersistent qgroup status.

  I mean the already known issues btrfs/153 (count error on write to
  falloc-ed space) and btrfs/179 (after a lot of snapshot
  create and distroy with fsstress on subvol the btrfs check
  reports qgroup count diff).

> For performance, we still have problem, but that should only be snapshot
> dropping.
> Balance is no longer a big problem.
> 
> Personally I think the current man page still stands.

  IMO kernel version in the man page is bit confusing though when
  its still unstable.

Thanks, Anand

> Thanks,
> Qu
>>
>> Signed-off-by: Anand Jain <anand.jain@oracle.com>
>> ---
>>   Documentation/btrfs-qgroup.asciidoc | 3 +--
>>   1 file changed, 1 insertion(+), 2 deletions(-)
>>
>> diff --git a/Documentation/btrfs-qgroup.asciidoc b/Documentation/btrfs-qgroup.asciidoc
>> index 0c9f5940a1d3..2da3d7819ba6 100644
>> --- a/Documentation/btrfs-qgroup.asciidoc
>> +++ b/Documentation/btrfs-qgroup.asciidoc
>> @@ -16,8 +16,7 @@ DESCRIPTION
>>   NOTE: To use qgroup you need to enable quota first using *btrfs quota enable*
>>   command.
>>   
>> -WARNING: Qgroup is not stable yet and will impact performance in current mainline
>> -kernel (v4.14).
>> +WARNING: Qgroup is an unstable feature as of now.
>>   
>>   QGROUP
>>   ------
>>
>
Qu Wenruo Jan. 24, 2020, 8:55 a.m. UTC | #3
On 2020/1/24 下午4:46, Anand Jain wrote:
> 
> 
> On 24/1/20 3:28 PM, Qu Wenruo wrote:
>>
>>
>> On 2020/1/24 下午3:25, Anand Jain wrote:
>>> There are known performance and counting errors for the quota when
>>> qgroup is
>>> enabled.
>>
>> Counting error is a big problem, please report if you found one not
>> caused by impersistent qgroup status.
> 
>  I mean the already known issues btrfs/153 (count error on write to
>  falloc-ed space) 

This is not count error, it's reserved space/limit error.

>and btrfs/179 (after a lot of snapshot
>  create and distroy with fsstress on subvol the btrfs check
>  reports qgroup count diff).

I haven't yet reproduce it, it would be nice to have a separate report.

> 
>> For performance, we still have problem, but that should only be snapshot
>> dropping.
>> Balance is no longer a big problem.
>>
>> Personally I think the current man page still stands.
> 
>  IMO kernel version in the man page is bit confusing though when
>  its still unstable.

OK, for the kernel version part the patch makes sense.

Thanks,
Qu

> 
> Thanks, Anand
> 
>> Thanks,
>> Qu
>>>
>>> Signed-off-by: Anand Jain <anand.jain@oracle.com>
>>> ---
>>>   Documentation/btrfs-qgroup.asciidoc | 3 +--
>>>   1 file changed, 1 insertion(+), 2 deletions(-)
>>>
>>> diff --git a/Documentation/btrfs-qgroup.asciidoc
>>> b/Documentation/btrfs-qgroup.asciidoc
>>> index 0c9f5940a1d3..2da3d7819ba6 100644
>>> --- a/Documentation/btrfs-qgroup.asciidoc
>>> +++ b/Documentation/btrfs-qgroup.asciidoc
>>> @@ -16,8 +16,7 @@ DESCRIPTION
>>>   NOTE: To use qgroup you need to enable quota first using *btrfs
>>> quota enable*
>>>   command.
>>>   -WARNING: Qgroup is not stable yet and will impact performance in
>>> current mainline
>>> -kernel (v4.14).
>>> +WARNING: Qgroup is an unstable feature as of now.
>>>     QGROUP
>>>   ------
>>>
>>
David Sterba Jan. 24, 2020, 5:22 p.m. UTC | #4
On Fri, Jan 24, 2020 at 04:55:23PM +0800, Qu Wenruo wrote:
> >> For performance, we still have problem, but that should only be snapshot
> >> dropping.
> >> Balance is no longer a big problem.
> >>
> >> Personally I think the current man page still stands.
> > 
> >  IMO kernel version in the man page is bit confusing though when
> >  its still unstable.
> 
> OK, for the kernel version part the patch makes sense.

Perhaps the page should be more specific about the problems (snapshot
deletion, metadata balance) and the versions where it's considered
problematic and since where it's not. The significant improvement for
the metadata balance you implemented is IMO worth mentioning, maybe also
on the wiki page feature changelog.
Anand Jain Jan. 24, 2020, 11:27 p.m. UTC | #5
On 25/1/20 1:22 AM, David Sterba wrote:
> On Fri, Jan 24, 2020 at 04:55:23PM +0800, Qu Wenruo wrote:
>>>> For performance, we still have problem, but that should only be snapshot
>>>> dropping.
>>>> Balance is no longer a big problem.
>>>>
>>>> Personally I think the current man page still stands.
>>>
>>>   IMO kernel version in the man page is bit confusing though when
>>>   its still unstable.
>>
>> OK, for the kernel version part the patch makes sense.
> 
> Perhaps the page should be more specific about the problems (snapshot
> deletion, metadata balance) and the versions where it's considered
> problematic and since where it's not. The significant improvement for
> the metadata balance you implemented is IMO worth mentioning, maybe also
> on the wiki page feature changelog.
> 

Good idea. Qu you may write new patch. I am taking this path back.
  Thanks.

Patch
diff mbox series

diff --git a/Documentation/btrfs-qgroup.asciidoc b/Documentation/btrfs-qgroup.asciidoc
index 0c9f5940a1d3..2da3d7819ba6 100644
--- a/Documentation/btrfs-qgroup.asciidoc
+++ b/Documentation/btrfs-qgroup.asciidoc
@@ -16,8 +16,7 @@  DESCRIPTION
 NOTE: To use qgroup you need to enable quota first using *btrfs quota enable*
 command.
 
-WARNING: Qgroup is not stable yet and will impact performance in current mainline
-kernel (v4.14).
+WARNING: Qgroup is an unstable feature as of now.
 
 QGROUP
 ------