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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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