Re: malloc cleanup and small optimization (step 2)

[kshe]

On Sat, 30 Dec 2017 11:50:53 +0000, Otto Moerbeek wrote:
> Slightly different diff: instead of initing all chunk_info structs in
> page, do it on demand at first use. Measurements show that a lot of
> programs only use a few chunk_info structs, so it is a bit wasteful to
> always initialize all of them. Also de-inline the init code for
> readability.

Perhaps a point of detail, but how about setting up the bitmap with

        i = p->total;
        memset(p->bits, 0xff, sizeof(p->bits[0]) * (i / MALLOC_BITS));
        if (i % MALLOC_BITS != 0)
                p->bits[i / MALLOC_BITS] = (1U << (i % MALLOC_BITS)) - 1;

or, since p->total should never be zero,

        i = p->total - 1;
        memset(p->bits, 0xff, sizeof(p->bits[0]) * (i / MALLOC_BITS));
        p->bits[i / MALLOC_BITS] = (2U << (i % MALLOC_BITS)) - 1;

instead of

        for (i = 0; p->total - i >= MALLOC_BITS; i += MALLOC_BITS)
                p->bits[i / MALLOC_BITS] = (u_short)~0U;
        if (i < p->total)
                p->bits[i / MALLOC_BITS] = 0;
        for (; i < p->total; i++)
                p->bits[i / MALLOC_BITS] |= (u_short)1U << (i % MALLOC_BITS);

at the end of the new init_chunk_info() function?

Besides, a few lines above those loops, I think p->shift could directly
be set to MALLOC_MINSHIFT when bits == 0, without having to recalculate
it from MALLOC_MINSIZE.

Regards,

kshe