Re: [PATCH 1/4] stringbuf: A string buffer implementation

Matthew Wilcox
2007-10-24T01:49:30Z

On Tue, Oct 23, 2007 at 05:11:16PM -0500, Matt Mackall wrote:
> You might want to consider growing the buffer by no less than a small
> constant factor like 1.3x. This will keep things that do short concats
> in a loop from degrading to O(n^2) performance due to realloc and
> memcpy.

I looked at slab and slub, and would grow the buffer by no less than
1.5x each time, thanks to the buckets. I'd initially implemented 2x,
but switched to allocating size+1 and calling ksize() as being a more
efficient implementation.

I presume slob is different? Actually, slob doesn't seem to
provide krealloc, so I think stringbuf won't work on slob. Will you
have time to fix this?

> Should probably just bite the bullet and pass a flag.

Hrm.

extern void sb_printf(struct stringbuf *sb, gfp_t gfp, const char *fmt, ...)
__attribute__((format(printf, 3, 4)));

? Any objections?

> > +#define INITIAL_SIZE 32
>
> Too small. That will guarantee that most users end up doing a realloc.
> Can we have 128 instead?

I don't care. Sure!

--
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