Slow byte manipulation on alpha stations ?

From: <wenger_at_SIMBAD.u-strasbg.fr>
Date: Thu, 20 Apr 95 14:51:57 +0200

Looking closely to station performances for what concerns heavy byte
manipulation applications, I found that DEC alpha stations seem to have
curious performances, compared to a SPARC 20-71 and a five years old
DEC5400 server (20 MHz Mips processor):

Compiled with cc -O2, this programme

---------------------------------------------------------
main()
{
        int i;
        char str1[8192], str2[8192], *p1, *p2, *pf ;

        pf = str1+8192;
        for (i=0; i < 10000; i++)
                for (p1=str1, p2=str2; p1 < pf; )
                        *p1++ = *p2++;
}
---------------------------------------------------------

executed with the 'time' command, gives:

DEC 3000-400 (alpha 133 Mhz) : 18.51u 0.01s 0:18 99% 0+1k 0+0io 15pf+0w
DEC 4000-710 (alpha 190 MHz) : 12.83u 0.01s 0:17 73% 3+1k 0+0io 81pf+0w
SUN SPARC 20-71 (SuperSparc II,65 Mhz): 4.4u 0.0s 0:06 65% 0+152k 0+0io 0pf+0w
DEC 5400 server (Mips R3000, 20 MHz) : 29.1u 0.1s 0:32 90% 4+23k 0+0io 0pf+0w

when 'normally' the alpha server is twice as fast as the Sparc and about
ten times faster that the old DEC 5400.



Then I checked some standard unix utilities which manipulate bytes:
sort, awk and grep both with regular expressions.

On a file containing 50,000 lines like following ones:

--------------------------------------------------
CKLYFXGYQDYRPCLMHTXFKBDVJEANMRRIFWLTYAXVVORJHWWPFN
KYKNGYSDPLNMFYMZUEEPHUWHSROECBBKYEUNTANPWMJOANANXB
GFGQIGBOEUDZWGZJVEHTRVCPUNOSISLSFPTUVHRKDKKOYYLTNT
--------------------------------------------------


I got these results (user cpu + syst cpu)

                                     DEC alpha DEC alpha SUN SPARC DEC
                                      3000-400 4000-710 20-71 5400


fgrep ABCD 1.35 0.96 1.0 7.5
grep ABCD 2.77 2.16 0.9 5.1
grep grep '^AA.*ZZ$' 6.58 5.86 0.6 3.7
sort 3.08 2.38 2.7 36.2
sort +5 -6 +10r -13 +20 -30 206.04 159.33 77.1 312.6
awk '/ABCD/ {print substr($0,20,10)}' 12.40 8.42 1.2 8.9

giving on some executions better rates with a 20 MHz DEC5400 that a 190 MHz
DEC alpha station ...


            Is the conclusion correct that DEC alpha processors
                 are not suited for manipulating bytes ?


Marc Wenger
wenger_at_astro.u-strasbg.fr
Received on Thu Apr 20 1995 - 08:52:39 NZST

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