On 24 Jun 2019, at 16:30, Rafael Vargas wrote:
> Em seg, 24 de jun de 2019 às 07:21, Eelco Chaudron
> <echaudro@xxxxxxxxxx> escreveu:
>
>> /* Stuff the ring with as much frames as possible */
>> stock_frames = xsk_ring_prod__free(&xsk->umem->fq);
>> stock_frames = MIN(stock_frames, xsk_umem_free_frames(xsk));
>>
>> if (stock_frames > 0) {
>>
>> ret = xsk_ring_prod__reserve(&xsk->umem->fq, stock_frames,
>> &idx_fq);
>> while (ret != stock_frames)
>> ret = xsk_ring_prod__reserve(&xsk->umem->fq, rcvd,
>> &idx_fq);
> once you've checked before the number of free entries, this while is
> still needed?
In theory not, just a safeguard…
>> Where xsk_ring_prod__free() is as follows (sent patch upstream for
>> adding it as an API):
>>
>> static inline __u32 xsk_ring_prod__free(struct xsk_ring_prod *r)
>> {
>> r->cached_cons = *r->consumer + r->size;
>> return r->cached_cons - r->cached_prod;
>> }
>
> this is basically xsk_prod_nb_free, but always triggering the cache
> refresh, right?
Yes, probably a xsk_prod_nb_free(, xsk_umem_free_frames(xsk)) would work
>>
>> And the following is an API around my UMEM frame handling:
>>
>> xsk_umem_free_frames() -> How many buffers do I have available on my
>> stack
>>
>> xsk_free_umem_frame() -> return a buffer to my buffer stack
>>
>> xsk_alloc_umem_frame() -> Get a buffer from my buffer stack
>>
>
> Is this API using another local ring or stack buffer or is it using
> some clever trick I'm not figuring out?
Just a simple array with all the UMEM addresses:
struct xsk_socket_info {
…
uint64_t umem_frame_addr[NUM_FRAMES];
uint32_t umem_frame_free;
}
static uint64_t xsk_alloc_umem_frame(struct xsk_socket_info *xsk)
{
uint64_t frame;
if (xsk->umem_frame_free == 0)
return INVALID_UMEM_FRAME;
frame = xsk->umem_frame_addr[--xsk->umem_frame_free];
xsk->umem_frame_addr[xsk->umem_frame_free] = INVALID_UMEM_FRAME;
return frame;
}
static void xsk_free_umem_frame(struct xsk_socket_info *xsk, uint64_t frame)
{
assert(xsk->umem_frame_free < NUM_FRAMES);
xsk->umem_frame_addr[xsk->umem_frame_free++] = frame;
}
static uint64_t xsk_umem_free_frames(struct xsk_socket_info *xsk)
{
return xsk->umem_frame_free;
}
> I'll try this approach, thanks!
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