Re: [PATCH] cat, cp, mv, install, split: Set the minimum IO block size used, to 64KiB

[Bernhard Voelker]

On 07/21/2011 01:21 PM, Pádraig Brady wrote:
> I'm a little wary of this being too aggressive,
> but it does give a noticeable (13%) boost on my new laptop.
> Here are the numbers from dd bs=$blksize if=/dev/zero of=/dev/null
>
>     blksize  system-1   system-2
>     ----------------------------
>        1024  734 MB/s   1.7 GB/s
>        2048  1.3 GB/s   3.0 GB/s
>        4096  2.4 GB/s   5.1 GB/s
>        8192  3.5 GB/s   7.3 GB/s
>       16384  3.9 GB/s   9.4 GB/s
>       32768  5.2 GB/s   9.9 GB/s
>       65536  5.3 GB/s  11.2 GB/s
>      131072  5.5 GB/s  11.8 GB/s
>      262144  5.7 GB/s  11.6 GB/s
>      524288  5.7 GB/s  11.4 GB/s
>     1048576  5.8 GB/s  11.4 GB/s

Hmm, I've taken the script from the test, but I'm not
quite sure about the numbers on my system:

$ for i in $(seq 0 10); do bs=$((1024*2**$i)); printf "%7s=" $bs; 
src/timeout --foreground -sINT 1 dd bs=$bs if=/dev/zero of=/dev/null 
2>&1 | sed -n 's/.* \([0-9.]* [GM]B\/s\)/\1/p' ; done
   1024=2.3 GB/s
   2048=4.0 GB/s
   4096=6.7 GB/s
   8192=9.7 GB/s
  16384=16.3 GB/s
  32768=31.3 GB/s
  65536=52.2 GB/s
 131072=81.6 GB/s
 262144=115 GB/s
 524288=141 GB/s
1048576=157 GB/s

I have a "Intel(R) Core(TM)2 Quad CPU    Q6600  @ 2.40GHz" system.
And I used `src/timeout` from the latest `git pull`.

Berny