lkml.org 
[lkml]   [2006]   [Dec]   [22]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [RFC] delayed allocation for ext4
    On Fri, Dec 22, 2006 at 11:20:08PM +0300, Alex Tomas wrote:
    >
    > Good day,
    >
    > probably the previous set of patches (including mballoc/lg)
    > is too large. so, I reworked delayed allocation a bit so
    > that it can be used on top of regular balloc, though it
    > still can be used with extents-enabled files only.
    >
    > this time series contains just 3 patches:
    >
    > - booked-page-flag.patch
    > adds PG_booked bit to page->flags. it's used in delayed
    > allocation to mark space is already reserved for page
    > (including possible metadata)

    So that mean's we'll have 2 separate mechanisms for marking
    pages as delalloc. XFS uses the BH_delay flag to indicate
    that a buffer (block) attached to the page is using delalloc.

    FWIW, how does this mechanism deal with block size < page size?
    Don't you have to track delalloc on a block basis rather than
    a page basis?

    > - ext4-block-reservation.patch
    > this is scalable free space management. every time we
    > delay allocation of some page, a space (including metadata)
    > should be reserved
    >
    > - ext4-delayed-allocation.patch
    > delayed allocation itself, enabled by "delalloc" mount option.
    > extents support is also required. currently it works only
    > with blocksize=pagesize.

    Ah, that's why you can get away with a page flag - you've ignored
    the partial page delay state problem. Any plans to use the
    existing method in the future so we will be able to use ext4 delalloc
    on machines with a page size larger than 4k?

    Cheers,

    Dave.
    --
    Dave Chinner
    Principal Engineer
    SGI Australian Software Group
    -
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    More majordomo info at http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at http://www.tux.org/lkml/

    \
     
     \ /
      Last update: 2006-12-23 04:35    [W:0.022 / U:63.360 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site