Messages in this thread | | | Date | Fri, 1 Aug 2014 18:04:15 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH 0/2] new API to allocate buffer-cache for superblock in non-movable area |
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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. [unhandled content-type:application/pgp-signature] | |