Messages in this thread | | | Date | Mon, 25 Oct 2004 16:45:16 -0700 | From | Andrew Morton <> | Subject | Re: [Ext2-devel] Re: [PATCH 2/3] ext3 reservation allow turn off for specifed file |
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Mingming Cao <cmm@us.ibm.com> wrote: > > /* > + * if user passed a seeky-access hint to kernel, > + * through POSIX_FADV_RANDOM,(file->r_ra.ra_pages is cleared) > + * turn off reservation for block allocation correspondingly. > + * > + * Otherwise, if user switch back to POSIX_FADV_SEQUENTIAL or > + * POSIX_FADV_NORMAL, re-open the reservation window. > + */ > + windowsz = atomic_read(&EXT3_I(inode)->i_rsv_window.rsv_goal_size); > + if ((windowsz > 0) && (!file->f_ra.ra_pages)) > + atomic_set(&EXT3_I(inode)->i_rsv_window.rsv_goal_size, -1); > + if ((windowsz == -1) && file->f_ra.ra_pages) > + atomic_set(&EXT3_I(inode)->i_rsv_window.rsv_goal_size, > + EXT3_DEFAULT_RESERVE_BLOCKS); > +
It's pretty sad that we add this extra code into ext3_prepare_write() - it's almost never actually executed.
I wonder how important this optimisation really is? I bet no applications are using posix_fadvise(POSIX_FADV_RANDOM) anyway.
It we really see that benefits are available from this approach we probably need to bite the bullet and add file_operations.fadvise() - 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/
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