[lkml]   [2010]   [May]   [7]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
    Subjectunified page and buffer cache? (was: readahead on directories)
    I thought that the buffer and page caches were unified long ago, but
    last night I modified ureadahead to call readahead() directly on the
    block device for all physical extents involved rather than open() each
    file and readahead() on that. It read all of the related blocks into
    the buffer cache nice and fast, which was then ignored and the data was
    read again when accessed normally during boot.

    So it seems that the buffer cache and page cache are still separate, and
    normal files only use the page cache, and directories only use the
    buffer cache, which is why readahead() fails when called on a directory.

    Can anyone confirm that my disappointed understanding is correct? I
    started experimenting with a workaround where I readahead directories
    via the block device, and normal files the normal way. This seems to do
    the trick, but is sub optimal since you have to read in two passes,
    picking up the directories on the first pass, then going back for the files.

     \ /
      Last update: 2010-05-07 15:41    [W:0.018 / U:42.432 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site