Hi Eelco, > -----Original Message----- > From: Eelco Chaudron <echau...@redhat.com> > Sent: Wednesday, May 17, 2023 5:09 PM > To: maxime.coque...@redhat.com; Xia, Chenbo <chenbo....@intel.com>; > david.march...@redhat.com > Cc: dev@dpdk.org > Subject: [PATCH v3 1/4] vhost: change vhost_virtqueue access lock to a > read/write one > > This change will allow the vhost interrupt datapath handling to be split > between two processed without one of them holding an explicit lock. > > Signed-off-by: Eelco Chaudron <echau...@redhat.com> > --- > lib/eal/include/generic/rte_rwlock.h | 17 ++++++ > lib/vhost/vhost.c | 46 +++++++++-------- > lib/vhost/vhost.h | 4 +- > lib/vhost/vhost_user.c | 14 +++-- > lib/vhost/virtio_net.c | 90 +++++++++++++++++------------ > ----- > 5 files changed, 94 insertions(+), 77 deletions(-) > > diff --git a/lib/eal/include/generic/rte_rwlock.h > b/lib/eal/include/generic/rte_rwlock.h > index 71e2d8d5f4..9e083bbc61 100644 > --- a/lib/eal/include/generic/rte_rwlock.h > +++ b/lib/eal/include/generic/rte_rwlock.h > @@ -236,6 +236,23 @@ rte_rwlock_write_unlock(rte_rwlock_t *rwl) > __atomic_fetch_sub(&rwl->cnt, RTE_RWLOCK_WRITE, __ATOMIC_RELEASE); > } > > +/** > + * Test if the write lock is taken. > + * > + * @param rwl > + * A pointer to a rwlock structure. > + * @return > + * 1 if the write lock is currently taken; 0 otherwise. > + */ > +static inline int > +rte_rwlock_write_is_locked(rte_rwlock_t *rwl) > +{ > + if (__atomic_load_n(&rwl->cnt, __ATOMIC_RELAXED) & RTE_RWLOCK_WRITE) > + return 1; > + > + return 0; > +} > +
Again we need to update release note as it's a new EAL API. > /** > * Try to execute critical section in a hardware memory transaction, if > it > * fails or not available take a read lock > diff --git a/lib/vhost/vhost.c b/lib/vhost/vhost.c > index ef37943817..74bdbfd810 100644 > --- a/lib/vhost/vhost.c > +++ b/lib/vhost/vhost.c > @@ -393,9 +393,9 @@ free_vq(struct virtio_net *dev, struct vhost_virtqueue > *vq) > else > rte_free(vq->shadow_used_split); > > - rte_spinlock_lock(&vq->access_lock); > + rte_rwlock_write_lock(&vq->access_lock); > vhost_free_async_mem(vq); > - rte_spinlock_unlock(&vq->access_lock); > + rte_rwlock_write_unlock(&vq->access_lock); > rte_free(vq->batch_copy_elems); > vhost_user_iotlb_destroy(vq); > rte_free(vq->log_cache); > @@ -630,7 +630,7 @@ alloc_vring_queue(struct virtio_net *dev, uint32_t > vring_idx) > > dev->virtqueue[i] = vq; > init_vring_queue(dev, vq, i); > - rte_spinlock_init(&vq->access_lock); > + rte_rwlock_init(&vq->access_lock); > vq->avail_wrap_counter = 1; > vq->used_wrap_counter = 1; > vq->signalled_used_valid = false; > @@ -1305,14 +1305,14 @@ rte_vhost_vring_call(int vid, uint16_t vring_idx) > if (!vq) > return -1; > > - rte_spinlock_lock(&vq->access_lock); > + rte_rwlock_read_lock(&vq->access_lock); > > if (vq_is_packed(dev)) > vhost_vring_call_packed(dev, vq); > else > vhost_vring_call_split(dev, vq); > > - rte_spinlock_unlock(&vq->access_lock); > + rte_rwlock_read_unlock(&vq->access_lock); Not sure about this. vhost_ring_call_packed/split is changing some field in Vq. Should we use write lock here? Thanks, Chenbo