Re: [PATCH 0/2] new API to allocate buffer-cache for superblock in non-movable area

Gioh Kim
2014-08-06T06:16:21Z

2014-08-02 오전 1:04, Peter Zijlstra 쓴 글:
> On Fri, Aug 01, 2014 at 05:24:59PM +0200, Jan Kara wrote:
>
>> OK, makes sense. But then if there's heavy IO going on, anything that has
>> IO pending on it is pinned and IO completion can easily take something
>> close to a second or more. So meeting subsecond deadlines may be tough even
>> for ordinary data pages under heavy load, even more so for metadata where
>> there are further constraints. OTOH phones aren't usually IO bound so in
>> practice it needn't be so bad ;).
>
> Yeah, typically phones are not IO bound :-)
>
>> So if it is sub-second unless someone
>> loads the storage, then that sounds doable even for metadata. But we'll
>> need to attach ->migratepage callback to blkdev pages and at least in ext4
>> case teach it how to move pages tracked by the journal.
>
> Right, making it possible at all if of course much prefered over not
> possible, regardless of timeliness :-)
>
>>> Sadly its not only mobile devices that excel in crappy hardware, there's
>>> plenty desktop stuff that could use this too, like some of the v4l
>>> devices iirc.
>> Yeah, but in such usecases the guarantees we can offer for completion of
>> migration are even more vague :(.
>
> Yeah, lets start by making it possible, after that we can maybe look at
> making it better, who knows.
>

Is my patch applicable? Or what do I have to do now?