Re: [9fans] slow performance

[erik quanstrom]

when you compiled this on plan 9, you must have 
either replaced stdlib.h with something else or have used
ape.  i substituted libbio and get almost the same performance
you did on linux.  i used my home cpu server, a amd64 revF 3800+.

        cpu% 8c -FVw t.c
        warning: t.c:64 set and not used: t
        cpu% 8l -o t t.8
        cpu% time t >/tmp/xyzw
        2.08u 0.05s 2.36r        t

i think the reason for the difference in performance is that somehow
your translation of print was calling write(2) for each integer printed.

assuming i understand the point of this program -- sorting a bunch of
integers, i rewrote this program using an array and qsort, which should
be more memory efficient and faster.  here's what i get

        cpu% time ./u >/tmp/xyz 
        0.08u 0.01s 0.22r        ./u

- erik
#include <u.h>
#include <libc.h>
#include <bio.h>

enum{
        MAX     = 200000,
};

typedef struct Bst Bst;
struct Bst{
        int     v;
        Bst     *menor;
        Bst     *maior;
};

Biobuf b;

Bst*
pbst(Bst *t)
{
        if(t->menor != 0)
                t->menor = pbst(t->menor);
        Bprint(&b, "%d - ", t->v);
        if(t->maior != 0)
                t->maior = pbst(t->maior);
        return t;
}

Bst*
bstini(int v)
{
        Bst *t;

        t = malloc(sizeof *t);
        t->v = v;
        t->maior = 0;
        t->menor = 0;
        return t;
}

Bst *
bstadd(int v, Bst *t)
{
        if(t == 0)
                t = bstini(v);
        else if(v >= t->v)
                t->maior = bstadd(v, t->maior);
        else
                t->menor = bstadd(v, t->menor);
        return t;
 }

void
main(void)
{
        Bst *t;
        int i;

        Binit(&b, 1, OWRITE);
        t = 0;
        srand(time(0));
        for(i = 0; i < MAX; i++)
                t = bstadd(rand()%1000, t);
        t = pbst(t);
        exits("");
 }
#include <u.h>
#include <libc.h>
#include <bio.h>

enum{
        MAX     = 200000,
};

int
intcmp(void *a, void *b)
{
        return *((int*)a)-*((int*)b);
}

void
main(void)
{
        Biobuf b;
        int *t, i;

        Binit(&b, 1, OWRITE);
        
        t = malloc(MAX*sizeof *t);
        srand(time(0));
        for(i = 0; i < MAX; i++)
                t[i] = rand()%1000;
        qsort(t, MAX, sizeof *t, intcmp);
        for(i = 0; i < MAX; i++)
                Bprint(&b, " - %d", t[i]);
        exits("");
 }