Re: [RFC PATCH 03/24] erofs: add Errno in Rust

Gao Xiang
2024-09-26T11:05:12Z

On 2024/9/26 19:01, Ariel Miculas wrote:

..

>
>> I believe they basically equal to your `Unified size`s, so
>> the result is
>>
>> Your unified size
>> EROFS (LZ4HC,12,64k) 54.2
>> PuzzleFS compressed 53?
>> EROFS (DEFLATE,9,32k) 46.4
>>
>> That is why I used your 53 unified size to show EROFS is much
>> smaller than PuzzleFS.
>>
>> The reason why EROFS and SquashFS doesn't have the `Total Size`s
>> is just because we cannot store every individual chunk into some
>> seperate file.
>
> Well storing individual chunks into separate files is the entire point
> of PuzzleFS.
>
>>
>> Currently, I have seen no reason to open arbitary kernel files
>> (maybe hundreds due to large folio feature at once) in the page
>> fault context. If I modified `mkfs.erofs` tool, I could give
>> some similar numbers, but I don't want to waste time now due
>> to `open arbitary kernel files in the page fault context`.
>>
>> As I said, if PuzzleFS finally upstream some work to open kernel
>> files in page fault context, I will definitely work out the same
>> feature for EROFS soon, but currently I don't do that just
>> because it's very controversal and no in-tree kernel filesystem
>> does that.
>
> The PuzzleFS kernel filesystem driver is still in an early POC stage, so
> there's still a lot more work to be done.

I suggest that you could just ask FS/MM folks about this ("open
kernel files when reading in the page fault") first.

If they say "no", I suggest please don't waste on this anymore.

Thanks,
Gao Xiang

>
> Regards,
> Ariel
>
>>
>> Thanks,
>> Gao Xiang