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    SubjectRe: File System Performance
    From
    Date
    On Mon, 2001-11-12 at 15:43, Andrew Morton wrote:

    >
    > It's tar. It cheats. It somehow detects that the
    > output is /dev/null, and so it doesn't read the input files.
    > I think.
    >

    Yep it cheats all right:

    execve("/bin/tar", ["tar", "cf", "/dev/null", "linux"], [/* 30 vars */])
    = 0
    % time seconds usecs/call calls errors syscall
    ------ ----------- ----------- --------- --------- ----------------
    59.70 1.114097 740 1505 getdents64
    37.22 0.694516 55 12650 lstat64
    1.62 0.030264 39 775 3 open
    0.56 0.010518 14 777 close
    0.40 0.007395 10 770 fstat64
    0.24 0.004553 6 749 fcntl64
    0.11 0.001972 986 2 poll
    0.02 0.000420 210 2 2 connect
    0.02 0.000418 32 13 read
    0.02 0.000345 20 17 old_mmap
    0.02 0.000286 36 8 munmap
    0.02 0.000281 18 16 mmap2
    0.01 0.000189 47 4 socket
    0.01 0.000161 16 10 brk
    0.01 0.000101 51 2 sendto
    0.00 0.000076 15 5 mprotect
    0.00 0.000076 38 2 recvfrom
    0.00 0.000075 25 3 uname
    0.00 0.000059 30 2 readv
    0.00 0.000057 29 2 bind
    0.00 0.000056 28 2 setsockopt
    0.00 0.000039 39 1 readlink
    0.00 0.000025 13 2 getpid
    0.00 0.000023 23 1 rt_sigaction
    0.00 0.000021 21 1 time
    0.00 0.000021 21 1 gettimeofday
    0.00 0.000014 7 2 ioctl
    ------ ----------- ----------- --------- --------- ----------------
    100.00 1.866058 17324 5 total

    Not a lot of reads in there.... I should have known it could
    not go that fast.

    Steve

    --

    Steve Lord voice: +1-651-683-3511
    Principal Engineer, Filesystem Software email: lord@sgi.com
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