RE: [PATCH 00/16] f2fs: introduce flash-friendly file system

[Changman Lee <cm224.lee@samsung.com>]

> -----Original Message-----
> From: Namjae Jeon [mailto:linkinjeon@gmail.com]
> Sent: Wednesday, October 17, 2012 8:14 PM
> To: Changman Lee
> Cc: Jaegeuk Kim; Vyacheslav Dubeyko; Marco Stornelli; Jaegeuk Kim; Al Viro;
> tytso@mit.edu; gregkh@linuxfoundation.org; linux-kernel@vger.kernel.org;
> chur.lee@samsung.com; cm224.lee@samsung.com; jooyoung.hwang@samsung.com;
> linux-fsdevel@vger.kernel.org
> Subject: Re: [PATCH 00/16] f2fs: introduce flash-friendly file system
> 
> 2012/10/11, Changman Lee <cm224.lee@gmail.com>:
> > 2012년 10월 11일 목요일에 Namjae Jeon<linkinjeon@gmail.com>님이 작성:
> >> 2012/10/10 Jaegeuk Kim <jaegeuk.kim@samsung.com>:
> >>
> >>>>
> >>>> I mean that every volume is placed inside any partition (MTD or GPT).
> > Every partition begins from any
> >>>> physical sector. So, as I can understand, f2fs volume can begin from
> > physical sector that is laid
> >>>> inside physical erase block. Thereby, in such case of formating the
> > f2fs's operation units will be
> >>>> unaligned in relation of physical erase blocks, from my point of view.
> > Maybe, I misunderstand
> >>>> something but it can lead to additional FTL operations and performance
> > degradation, from my point of
> >>>> view.
> >>>
> >>> I think mkfs already calculates the offset to align that.
> >> I think this answer is not what he want.
> >> If you don't use partition table such as dos partition table or gpt, I
> >> think that it is possible to align using mkfs.
> >> But If we should consider partition table space in storage, I don't
> >> understand how it  could be align using mkfs.
> >>
> >> Thanks.
> >
> > We can know the physical starting sector address of any partitions from
> > hdio geometry information got by ioctl.
> If so, first block and end block of partition are useless ?
> 
> Thanks.

For example.
If we try to align a start point of F2FS in 2MB but start sector of any partition is not aligned in 2MB,
and of course F2FS will have some unused blocks. Instead, F2FS could reduce gc cost of ftl.
I don't know my answer is what you want.

> >
> >>> Thanks,
> >>>
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> >