Re: [PATCH RFC] common/btrfs: use _scratch_cycle_mount to ensure all page caches are dropped

[Qu Wenruo <quwenruo.btrfs@gmx.com>]

On 2023/6/10 14:46, Zorro Lang wrote:
> On Fri, Jun 09, 2023 at 07:57:37AM +0800, Qu Wenruo wrote:
>>
>>
>> On 2023/6/8 20:15, Christoph Hellwig wrote:
>>> On Thu, Jun 08, 2023 at 07:48:36PM +0800, Qu Wenruo wrote:
>>>>    	echo 3 > /proc/sys/vm/drop_caches
>>>> +	# Above drop_caches doesn't seem to drop every pages on aarch64 with
>>>> +	# 64K page size.
>>>> +	# So here as a workaround, cycle mount the SCRATCH_MNT to ensure
>>>> +	# the cache are dropped.
>>>> +	_scratch_cycle_mount
>>>
>>> The _scratch_cycle_mount looks ok to me, but if we do that, there is
>>> really no point in doing the drop_caches as well.
>>
>> Yep, we can remove that line. It's mostly a reminder for me to dig out why
>> that drop_caches doesn't work as expected.
>
> How about leaving a reminder/explanation in comment, remove that real drop_caches
> line. If no objection, I'll merge this patch with this change.

We can reuse the comment in the patch, which is already mentioning
drop_caches doesn't always work at least on aarch64.

I'm fine dropping the "echo 3 > drop_caches" line.

Thanks,
Qu
>
> Thanks,
> Zorro
>
>>
>> Thanks,
>> Qu
>>
>