Re: [POC for v5.15 0/2] btrfs: defrag: what if v5.15 is doing proper defrag

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

On 2022/2/4 19:05, François-Xavier Thomas wrote:
>> But one thing to mention is, the color scheme is little weird to me.
>
> Good point, here's a custom graph with just the write rate, that
> should be easier to read than the default graph with everything:
> https://i.imgur.com/vlRPOFr.png

This is indeed way better.

Although now the legend only shows write MB/s, but I still see some pink
lines.

Does the pink line still belongs to the sda write MB/s?
Or it's just the read MB/s?

And if possible, read MB/s would also help.
>
> Waiting for your next update then. In the mean time are there other
> statistics I should collect that would make this easier to debug?

Other debug data can be too large and slow down the system, like ftrace
event for each cluster.

Another thing which can greatly help is sorting the IO by its METADATA flag.
(E.g. providing metadata/data read/write MB/s separately)

But unfortunately I don't have any idea to monitor it without using eBPF...

Thanks,
Qu
>
> Thanks,
> François-Xavier