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    SubjectRe: -mm merge plans for 2.6.23
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    On Wed, 25 Jul 2007 07:30:37 +0200, Rene Herman said:

    > Yes, but what's locate's usage scenario? I've never, ever wanted to use it.
    > When do you know the name of something but not where it's located, other
    > than situations which "which" wouldn't cover and after just having
    > installed/unpacked something meaning locate doesn't know about it yet either?

    My favorite use - with 5 Fedora kernels and as many -mm kernels on my laptop,
    doing a 'locate moby' finds all the moby.c and moby.o and moby.ko for
    the various releases. For bonus points, something like:

    ls -lt `locate iwl3945.ko`

    to find all 19 copies that are on my system, and remind me which ones were
    compiled when. Or just when you remember the name of some one-off 100-line
    Perl program that you wrote 6 months ago, but not sure which directory you
    left it in... ;)

    You want hard numbers? Here you go - 'locate' versus 'find'
    (/usr/src/ has about 290K files on it):

    % strace locate iwl3945.ko >| /tmp/foo3 2>&1
    % wc /tmp/foo3
    96 592 6252 /tmp/foo3
    % strace find /usr/src /lib -name iwl3945.ko >| /tmp/foo4 2>&1
    % wc /tmp/foo4
    328380 1550032 15708205 /tmp/foo4

    # echo 1 > /proc/sys/vm/drop_caches (to empty the caches

    % time locate iwl3945.ko > /dev/null

    real 0m0.872s
    user 0m0.867s
    sys 0m0.008s

    % time find /usr/src /lib -name iwl3945.ko > /dev/null
    find: /usr/src/lost+found: Permission denied

    real 1m12.241s
    user 0m1.128s
    sys 0m3.566s

    So 96 system calls in 1 second, against 328K calls in a minute. There's your
    use case, right there. Now if we can just find a way for that find/updatedb
    to not be as painful to the rest of the system.....




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