Re: [patch 2/4 -mm] flex_array: add flex_array_clear function

From: David Rientjes
Date: Mon Aug 24 2009 - 16:30:06 EST

On Mon, 24 Aug 2009, Dave Hansen wrote:

> My only worry about this is that it's largely a copy-and-paste of
> flex_array_put(). If we had a function that just returned a pointer to
> 'dst', we could use that in both cases.
> Couldn't we implement the above with just:
> int flex_array_clear(struct flex_array *fa, unsigned int element_nr)
> {
> return flex_array_put(fa, element_nr, &empty_zero_page);
> }

Sure, if you never increase FLEX_ARRAY_PART_SIZE. Otherwise, doing

static char zero_part[FLEX_ARRAY_PART_SIZE] = {
[0 ... FLEX_ARRAY_PART_SIZE - 1] = 0

and using flex_array_put(fa, element_nr, &zero_part) would work although
you're trading off cleaner, yet not more efficient, code at the cost of
FLEX_ARRAY_PART_SIZE wasted memory and memcpy() being slower than
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