On 11/16/20, Denis Kirjanov <kda@xxxxxxxxxxxxxxxxx> wrote:
> On 11/16/20, Xuan Zhuo <xuanzhuo@xxxxxxxxxxxxxxxxx> wrote:
>> On Mon, 16 Nov 2020 12:13:21 +0300, Denis Kirjanov
>> <kda@xxxxxxxxxxxxxxxxx>
>> wrote:
>>> On 11/16/20, Xuan Zhuo <xuanzhuo@xxxxxxxxxxxxxxxxx> wrote:
>>> > When we write all cq items to tx, we have to wait for a new event
>>> > based
>>> > on poll to indicate that it is writable. But the current writability
>>> > is
>>> > triggered based on whether tx is full or not, and In fact, when tx is
>>> > dissatisfied, the user of cq's item may not necessarily get it,
>>> > because
>>> > it
>>> > may still be occupied by the network card. In this case, we need to
>>> > know
>>> > when cq is available, so this patch adds a socket option, When the
>>> > user
>>> > configures this option using setsockopt, when cq is available, a
>>> > readable event is generated for all xsk bound to this umem.
>>> >
>>> > I can't find a better description of this event,
>>> > I think it can also be 'readable', although it is indeed different
>>> > from
>>> > the 'readable' of the new data. But the overhead of xsk checking
>>> > whether
>>> > cq or rx is readable is small.
>>> >
>>> > Signed-off-by: Xuan Zhuo <xuanzhuo@xxxxxxxxxxxxxxxxx>
>>> > ---
>>> > include/net/xdp_sock.h | 1 +
>>> > include/uapi/linux/if_xdp.h | 1 +
>>> > net/xdp/xsk.c | 28 ++++++++++++++++++++++++++++
>>> > 3 files changed, 30 insertions(+)
>>> >
>>> > diff --git a/include/net/xdp_sock.h b/include/net/xdp_sock.h
>>> > index 1a9559c..faf5b1a 100644
>>> > --- a/include/net/xdp_sock.h
>>> > +++ b/include/net/xdp_sock.h
>>> > @@ -49,6 +49,7 @@ struct xdp_sock {
>>> > struct xsk_buff_pool *pool;
>>> > u16 queue_id;
>>> > bool zc;
>>> > + bool cq_event;
>>> > enum {
>>> > XSK_READY = 0,
>>> > XSK_BOUND,
>>> > diff --git a/include/uapi/linux/if_xdp.h b/include/uapi/linux/if_xdp.h
>>> > index a78a809..2dba3cb 100644
>>> > --- a/include/uapi/linux/if_xdp.h
>>> > +++ b/include/uapi/linux/if_xdp.h
>>> > @@ -63,6 +63,7 @@ struct xdp_mmap_offsets {
>>> > #define XDP_UMEM_COMPLETION_RING 6
>>> > #define XDP_STATISTICS 7
>>> > #define XDP_OPTIONS 8
>>> > +#define XDP_CQ_EVENT 9
>>> >
>>> > struct xdp_umem_reg {
>>> > __u64 addr; /* Start of packet data area */
>>> > diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c
>>> > index cfbec39..0c53403 100644
>>> > --- a/net/xdp/xsk.c
>>> > +++ b/net/xdp/xsk.c
>>> > @@ -285,7 +285,16 @@ void __xsk_map_flush(void)
>>> >
>>> > void xsk_tx_completed(struct xsk_buff_pool *pool, u32 nb_entries)
>>> > {
>>> > + struct xdp_sock *xs;
>>> > +
>>> > xskq_prod_submit_n(pool->cq, nb_entries);
>>> > +
>>> > + rcu_read_lock();
>>> > + list_for_each_entry_rcu(xs, &pool->xsk_tx_list, tx_list) {
>>> > + if (xs->cq_event)
>>> > + sock_def_readable(&xs->sk);
>>> > + }
>>> > + rcu_read_unlock();
>>> > }
>>> > EXPORT_SYMBOL(xsk_tx_completed);
>>> >
>>> > @@ -495,6 +504,9 @@ static __poll_t xsk_poll(struct file *file, struct
>>> > socket *sock,
>>> > __xsk_sendmsg(sk);
>>> > }
>>> >
>>> > + if (xs->cq_event && pool->cq && !xskq_prod_is_empty(pool->cq))
>>> > + mask |= EPOLLIN | EPOLLRDNORM;
>>> > +
>>> > if (xs->rx && !xskq_prod_is_empty(xs->rx))
>>> > mask |= EPOLLIN | EPOLLRDNORM;
>>> > if (xs->tx && !xskq_cons_is_full(xs->tx))
>>> > @@ -882,6 +894,22 @@ static int xsk_setsockopt(struct socket *sock,
>>> > int
>>> > level, int optname,
>>> > mutex_unlock(&xs->mutex);
>>> > return err;
>>> > }
>>> > + case XDP_CQ_EVENT:
>>> > + {
>>> > + int cq_event;
>>> > +
>>> > + if (optlen < sizeof(cq_event))
>>> > + return -EINVAL;
>>> > + if (copy_from_sockptr(&cq_event, optval, sizeof(cq_event)))
>>> > + return -EFAULT;
>>> > +
>>> > + if (cq_event)
>>> > + xs->cq_event = true;
>>> > + else
>>> > + xs->cq_event = false;
>>>
>>> It's false by default, isn't it?
>>
>> I add cq_event inside "xdp_sock", that is got by sk_alloc, this call
>> sk_prot_alloc by __GFP_ZERO. So I think it is false.
>
> Right, I meant that what's the point to set it explicitly to 'false'?
Nevermind, It's okay.
>
>>
>> Thanks.
>>
>>>
>>> > +
>>> > + return 0;
>>> > + }
>>> > default:
>>> > break;
>>> > }
>>> > --
>>> > 1.8.3.1
>>> >
>>> >
>>
>
