Re: [PATCH 44/49] xfs: Reduce allocations during CIL insertion

Michael L. Semon
2013-07-23T21:44:44Z

On 07/23/2013 05:15 PM, Mark Tinguely wrote:
> On 07/19/13 01:25, Dave Chinner wrote:
>> From: Dave Chinner<dchinner@redhat.com>
>>
>> Now that we have the size of the object before the formatting pass
>> is called, we can allocation the log vector and it's buffer in a
>> single allocation rather than two separate allocations.
>>
>> Store the size of the allocated buffer in the log vector so that
>> we potentially avoid allocation for future modifications of the
>> object.
>>
>> While touching this code, remove the IOP_FORMAT definition.
>>
>> Signed-off-by: Dave Chinner<dchinner@redhat.com>
>
> Looks good.
>
> Reviewed-by: Mark Tinguely <tinguely@sgi.com>
>
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I'd like to register a gentle "test this well" protest on this patch.
While trying to figure out the origin of an unrelated lockdep, I
tried to copy 3 kernel gits from one 2k non-CRC XFS filesystem to
another one. With at least this patch used, the cp operation stops,
leading to not-umountable, not-syncable filesystems. It might be
while copying the 2nd git, or the 3rd git, while copying header files,
or while copying those large *.pack files, but it will happen
somewhere.

A bisect of the issue ends on this patch, but its removal means that
45_49 and 46_49 cannot be applied without good knowledge of the code
to be patched.

This one's on me for not being able to get good information to Dave.
If I can find a way to get trace-cmd to pipe over ssh or something
like that, then maybe there's a chance to make a file that `trace-cmd
report` can read. Previous attempts to save to different filesystems
or save over NFS and CIFS have all failed. Will keep trying...

For diagnosing this patch, is there an effective trace that is rather
small? And would you need more than just the XFS events?

Thanks!

Michael