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    SubjectRe: Per process mount options?
    Hello!

    In article <Pine.LNX.3.96.980414112258.599B-100000@localhost> you write:
    >On Tue, 14 Apr 1998, Lars Marowsky-Bree wrote:

    >> [...]

    >> I just watched our backup system blaze over the fs and thought how nice it
    >> would be if I could enable no_atime for tar, so it really would just read
    >> instead of consuming huge resources because it has to update no_atime for
    >> gazillion files.

    >milliways [~/]> tar --help | grep atime
    > --atime-preserve don't change access times on dumped files

    The --atime-preserve option of GNU tar doesn't affect the performance
    considerations brought in by Lars. I suppose --atime-preserve is
    implemented by (f)stat()ing the file in question (which has to be
    done anyway, for the attributes in the tar file header), and (f)utimes()
    to reset the atime after archiving the file. The kernel still sees the
    inode to be dirty (atime update from reading, then from utimes() - it
    probably doesn't know that the new value of the atime is exactly equal
    to the old one - as well as ctime updated by utimes()). So the
    inode has to be written back for each archived file, which wouldn't have
    to be done if some noatime thing were active in the filesystem layer.

    Regards, Felix.

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