Re: [RFC PATCH] mm: trace filemap add and del

Robert Jarzmik
2012-11-22T19:05:31Z

Dave Chinner <david@fromorbit.com> writes:

> We actually have an informal convention for formating filesystem
> trace events, and that is to use the device number....
>
>>
>> > + ),
>> > +
>> > + TP_printk("page=%p pfn=%lu blk=%d:%d inode+ofs=%lu+%lu",
>
> ... and to prefix messages like:
>
> TP_printk("dev %d:%d ino 0x%llx ....
> MAJOR(__entry->dev), MINOR(__entry->dev),
>
> i.e. the start of the event message has all the identifying
> information where it is easy to grep for and get all the events for
> a specific dev/inode combination without even having to think about
> it.

I cross-checked your proposition.
The "ino 0x%llx" looks wrong to me, because :
- i_ino is "unsigned long", not "(unsigned) long long"

- triggers a printk where "ino" looks really awfull (on a 32bits LE arm)
> mm_filemap_add_to_page_cache: dev 0:2 ino 0xc05186e000000000 page=000a0737
> pfn=0 ofs=3283861504

- why print the inode number in hexadecimal format ???
Doing a "ls -i" returns decimal format, "debugfs" returns decimal. What is
the rational behind hexadecimal ?

I'd rather have : "dev %d:%d ino %lu page=0x%p pfn=%lu ofs=%lu".

--
Robert