Hello, Al.
On Wed, Mar 05, 2014 at 03:49:19AM +0000, Al Viro wrote:
> convert ->map[] to array of offsets, cache the "no free areas among the
> first N" in chunk. Free/in-use is represented by the LSB, a sentry
> element (<free = false, offset = total size of chunk>) is added in
> the end.
Can you please add why this change is necessary to the description?
Also, I think it'd be better to split addition of first_free hint to a
separate patch.
> static void pcpu_split_block(struct pcpu_chunk *chunk, int i,
> - int head, int tail)
> + int head, int size, int tail)
> {
> int nr_extra = !!head + !!tail;
> + int off;
>
> - BUG_ON(chunk->map_alloc < chunk->map_used + nr_extra);
> + BUG_ON(chunk->map_alloc <= chunk->map_used + nr_extra);
>
> /* insert new subblocks */
> - memmove(&chunk->map[i + nr_extra], &chunk->map[i],
> + memmove(&chunk->map[i + nr_extra] + 1, &chunk->map[i] + 1,
> sizeof(chunk->map[0]) * (chunk->map_used - i));
> chunk->map_used += nr_extra;
>
> - if (head) {
> - chunk->map[i + 1] = chunk->map[i] - head;
> - chunk->map[i++] = head;
> - }
> - if (tail) {
> - chunk->map[i++] -= tail;
> - chunk->map[i] = tail;
> - }
> + off = chunk->map[i];
> +
> + if (head)
> + chunk->map[++i] = off += head;
> + if (tail)
> + chunk->map[++i] = off += size;
> }
Do we need to pass @size in the above function? Isn't that something
which can be easily determined? If @size is gonna stay, we'll need to
update the function comment too.
> /**
> @@ -483,19 +483,27 @@ static int pcpu_alloc_area(struct pcpu_chunk *chunk, int size, int align)
> int oslot = pcpu_chunk_slot(chunk);
> int max_contig = 0;
> int i, off;
> + int seen_free = 0;
bool
> @@ -570,34 +584,50 @@ static int pcpu_alloc_area(struct pcpu_chunk *chunk, int size, int align)
> static void pcpu_free_area(struct pcpu_chunk *chunk, int freeme)
> {
> int oslot = pcpu_chunk_slot(chunk);
> - int i, off;
> -
> - for (i = 0, off = 0; i < chunk->map_used; off += abs(chunk->map[i++]))
> - if (off == freeme)
> - break;
> + int off = 0;
> + unsigned i, j;
> + int to_free = 0;
> + int *p;
> +
> + freeme |= 1;
> +
> + i = 0;
> + j = chunk->map_used;
> + while (i != j) {
> + unsigned k = (i + j) / 2;
> + off = chunk->map[k];
> + if (off < freeme)
> + i = k + 1;
> + else if (off > freeme)
> + j = k;
> + else
> + i = j = k;
> + }
> BUG_ON(off != freeme);
> - BUG_ON(chunk->map[i] > 0);
A comment explaining why ignoring the free bit during bin search is
okay would be nice?
> @@ -617,7 +647,9 @@ static struct pcpu_chunk *pcpu_alloc_chunk(void)
> }
>
> chunk->map_alloc = PCPU_DFL_MAP_ALLOC;
> - chunk->map[chunk->map_used++] = pcpu_unit_size;
> + chunk->map[0] = 0;
> + chunk->map[1] = pcpu_unit_size | 1;
> + chunk->map_used = 1;
>
> INIT_LIST_HEAD(&chunk->list);
> chunk->free_size = pcpu_unit_size;
> @@ -713,6 +745,9 @@ static void __percpu *pcpu_alloc(size_t size, size_t align, bool reserved)
> unsigned long flags;
> void __percpu *ptr;
>
> + if (unlikely(align < 2))
> + align = 2;
Please add a comment explaining why the above min alignment is
necessary.
Other than the above, looks good to me.
Thanks.
--
tejun
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