Minor fix brought to my attention by MaxG. On 5/19/2020 3:43 PM, Yamin Friedman wrote: > Allow a ULP to ask the core to provide a completion queue based on a > least-used search on a per-device CQ pools. The device CQ pools grow in a > lazy fashion when more CQs are requested. > > This feature reduces the amount of interrupts when using many QPs. > Using shared CQs allows for more effcient completion handling. It also > reduces the amount of overhead needed for CQ contexts. > > Test setup: > Intel(R) Xeon(R) Platinum 8176M CPU @ 2.10GHz servers. > Running NVMeoF 4KB read IOs over ConnectX-5EX across Spectrum switch. > TX-depth = 32. The patch was applied in the nvme driver on both the target > and initiator. Four controllers are accessed from each core. In the > current test case we have exposed sixteen NVMe namespaces using four > different subsystems (four namespaces per subsystem) from one NVM port. > Each controller allocated X queues (RDMA QPs) and attached to Y CQs. > Before this series we had X == Y, i.e for four controllers we've created > total of 4X QPs and 4X CQs. In the shared case, we've created 4X QPs and > only X CQs which means that we have four controllers that share a > completion queue per core. Until fourteen cores there is no significant > change in performance and the number of interrupts per second is less than > a million in the current case. > ================================================== > |Cores|Current KIOPs |Shared KIOPs |improvement| > |-----|---------------|--------------|-----------| > |14 |2332 |2723 |16.7% | > |-----|---------------|--------------|-----------| > |20 |2086 |2712 |30% | > |-----|---------------|--------------|-----------| > |28 |1971 |2669 |35.4% | > |================================================= > |Cores|Current avg lat|Shared avg lat|improvement| > |-----|---------------|--------------|-----------| > |14 |767us |657us |14.3% | > |-----|---------------|--------------|-----------| > |20 |1225us |943us |23% | > |-----|---------------|--------------|-----------| > |28 |1816us |1341us |26.1% | > ======================================================== > |Cores|Current interrupts|Shared interrupts|improvement| > |-----|------------------|-----------------|-----------| > |14 |1.6M/sec |0.4M/sec |72% | > |-----|------------------|-----------------|-----------| > |20 |2.8M/sec |0.6M/sec |72.4% | > |-----|------------------|-----------------|-----------| > |28 |2.9M/sec |0.8M/sec |63.4% | > ==================================================================== > |Cores|Current 99.99th PCTL lat|Shared 99.99th PCTL lat|improvement| > |-----|------------------------|-----------------------|-----------| > |14 |67ms |6ms |90.9% | > |-----|------------------------|-----------------------|-----------| > |20 |5ms |6ms |-10% | > |-----|------------------------|-----------------------|-----------| > |28 |8.7ms |6ms |25.9% | > |=================================================================== > > Performance improvement with sixteen disks (sixteen CQs per core) is > comparable. > > Signed-off-by: Yamin Friedman > Reviewed-by: Or Gerlitz > Reviewed-by: Max Gurtovoy > Reviewed-by: Leon Romanovsky > --- > drivers/infiniband/core/core_priv.h | 3 + > drivers/infiniband/core/cq.c | 144 ++++++++++++++++++++++++++++++++++++ > drivers/infiniband/core/device.c | 2 + > include/rdma/ib_verbs.h | 35 +++++++++ > 4 files changed, 184 insertions(+) > > diff --git a/drivers/infiniband/core/core_priv.h b/drivers/infiniband/core/core_priv.h > index cf42acc..a1e6a67 100644 > --- a/drivers/infiniband/core/core_priv.h > +++ b/drivers/infiniband/core/core_priv.h > @@ -414,4 +414,7 @@ void rdma_umap_priv_init(struct rdma_umap_priv *priv, > struct vm_area_struct *vma, > struct rdma_user_mmap_entry *entry); > > +void ib_cq_pool_init(struct ib_device *dev); > +void ib_cq_pool_destroy(struct ib_device *dev); > + > #endif /* _CORE_PRIV_H */ > diff --git a/drivers/infiniband/core/cq.c b/drivers/infiniband/core/cq.c > index 4f25b24..7175295 100644 > --- a/drivers/infiniband/core/cq.c > +++ b/drivers/infiniband/core/cq.c > @@ -7,7 +7,11 @@ > #include > #include > > +#include "core_priv.h" > + > #include > +/* Max size for shared CQ, may require tuning */ > +#define IB_MAX_SHARED_CQ_SZ 4096 > > /* # of WCs to poll for with a single call to ib_poll_cq */ > #define IB_POLL_BATCH 16 > @@ -218,6 +222,7 @@ struct ib_cq *__ib_alloc_cq_user(struct ib_device *dev, void *private, > cq->cq_context = private; > cq->poll_ctx = poll_ctx; > atomic_set(&cq->usecnt, 0); > + cq->comp_vector = comp_vector; > > cq->wc = kmalloc_array(IB_POLL_BATCH, sizeof(*cq->wc), GFP_KERNEL); > if (!cq->wc) > @@ -309,6 +314,8 @@ void ib_free_cq_user(struct ib_cq *cq, struct ib_udata *udata) > { > if (WARN_ON_ONCE(atomic_read(&cq->usecnt))) > return; > + if (WARN_ON_ONCE(cq->cqe_used)) > + return; > > switch (cq->poll_ctx) { > case IB_POLL_DIRECT: > @@ -334,3 +341,140 @@ void ib_free_cq_user(struct ib_cq *cq, struct ib_udata *udata) > kfree(cq); > } > EXPORT_SYMBOL(ib_free_cq_user); > + > +void ib_cq_pool_init(struct ib_device *dev) > +{ > + int i; > + > + spin_lock_init(&dev->cq_pools_lock); > + for (i = 0; i < ARRAY_SIZE(dev->cq_pools); i++) > + INIT_LIST_HEAD(&dev->cq_pools[i]); > +} > + > +void ib_cq_pool_destroy(struct ib_device *dev) > +{ > + struct ib_cq *cq, *n; > + int i; > + > + for (i = 0; i < ARRAY_SIZE(dev->cq_pools); i++) { > + list_for_each_entry_safe(cq, n, &dev->cq_pools[i], > + pool_entry) { > + cq->shared = false; > + ib_free_cq_user(cq, NULL); > + } > + } > + > +} > + > +static int ib_alloc_cqs(struct ib_device *dev, int nr_cqes, > + enum ib_poll_context poll_ctx) > +{ > + LIST_HEAD(tmp_list); > + struct ib_cq *cq; > + unsigned long flags; > + int nr_cqs, ret, i; > + > + /* > + * Allocated at least as many CQEs as requested, and otherwise > + * a reasonable batch size so that we can share CQs between > + * multiple users instead of allocating a larger number of CQs. > + */ > + nr_cqes = min(dev->attrs.max_cqe, max(nr_cqes, IB_MAX_SHARED_CQ_SZ)); > + nr_cqs = min_t(int, dev->num_comp_vectors, num_online_cpus()); > + for (i = 0; i < nr_cqs; i++) { > + cq = ib_alloc_cq(dev, NULL, nr_cqes, i, poll_ctx); > + if (IS_ERR(cq)) { > + ret = PTR_ERR(cq); > + goto out_free_cqs; > + } > + cq->shared = true; > + list_add_tail(&cq->pool_entry, &tmp_list); > + } > + > + spin_lock_irqsave(&dev->cq_pools_lock, flags); > + list_splice(&tmp_list, &dev->cq_pools[poll_ctx - 1]); > + spin_unlock_irqrestore(&dev->cq_pools_lock, flags); > + > + return 0; > + > +out_free_cqs: > + list_for_each_entry(cq, &tmp_list, pool_entry) { > + cq->shared = false; > + ib_free_cq(cq); > + } > + return ret; > +} > + > +struct ib_cq *ib_cq_pool_get(struct ib_device *dev, unsigned int nr_cqe, > + int comp_vector_hint, > + enum ib_poll_context poll_ctx) > +{ > + static unsigned int default_comp_vector; > + int vector, ret, num_comp_vectors; > + struct ib_cq *cq, *found = NULL; > + unsigned long flags; > + > + if (poll_ctx > ARRAY_SIZE(dev->cq_pools) || poll_ctx == IB_POLL_DIRECT) > + return ERR_PTR(-EINVAL); > + > + num_comp_vectors = min_t(int, dev->num_comp_vectors, > + num_online_cpus()); > + /* Project the affinty to the device completion vector range */ > + if (comp_vector_hint < 0) > + vector = default_comp_vector++ % num_comp_vectors; > + else > + vector = comp_vector_hint % num_comp_vectors; > + > + /* > + * Find the least used CQ with correct affinity and > + * enough free CQ entries > + */ > + while (!found) { > + spin_lock_irqsave(&dev->cq_pools_lock, flags); > + list_for_each_entry(cq, &dev->cq_pools[poll_ctx - 1], > + pool_entry) { > + /* > + * Check to see if we have found a CQ with the > + * correct completion vector > + */ > + if (vector != cq->comp_vector) > + continue; > + if (cq->cqe_used + nr_cqe > cq->cqe) > + continue; > + found = cq; > + break; > + } > + > + if (found) { > + found->cqe_used += nr_cqe; > + spin_unlock_irqrestore(&dev->cq_pools_lock, flags); > + > + return found; > + } > + spin_unlock_irqrestore(&dev->cq_pools_lock, flags); > + > + /* > + * Didn't find a match or ran out of CQs in the device > + * pool, allocate a new array of CQs. > + */ > + ret = ib_alloc_cqs(dev, nr_cqe, poll_ctx); > + if (ret) > + return ERR_PTR(ret); > + } > + > + return found; > +} > +EXPORT_SYMBOL(ib_cq_pool_get); > + > +void ib_cq_pool_put(struct ib_cq *cq, unsigned int nr_cqe) > +{ > + unsigned long flags; > + > + if (WARN_ON_ONCE(nr_cqe > cq->cqe_used)) > + return; > + > + spin_lock_irqsave(&cq->device->cq_pools_lock, flags); > + cq->cqe_used -= nr_cqe; > + spin_unlock_irqrestore(&cq->device->cq_pools_lock, flags); > +} > +EXPORT_SYMBOL(ib_cq_pool_put); > diff --git a/drivers/infiniband/core/device.c b/drivers/infiniband/core/device.c > index d9f565a..0966f86 100644 > --- a/drivers/infiniband/core/device.c > +++ b/drivers/infiniband/core/device.c > @@ -1418,6 +1418,7 @@ int ib_register_device(struct ib_device *device, const char *name) > device->ops.dealloc_driver = dealloc_fn; > return ret; > } > + ib_cq_pool_init(device); > ib_device_put(device); > > return 0; > @@ -1446,6 +1447,7 @@ static void __ib_unregister_device(struct ib_device *ib_dev) > if (!refcount_read(&ib_dev->refcount)) > goto out; > > + ib_cq_pool_destroy(ib_dev); > disable_device(ib_dev); > > /* Expedite removing unregistered pointers from the hash table */ > diff --git a/include/rdma/ib_verbs.h b/include/rdma/ib_verbs.h > index 1659131..d40604a 100644 > --- a/include/rdma/ib_verbs.h > +++ b/include/rdma/ib_verbs.h > @@ -1555,6 +1555,7 @@ enum ib_poll_context { > IB_POLL_SOFTIRQ, /* poll from softirq context */ > IB_POLL_WORKQUEUE, /* poll from workqueue */ > IB_POLL_UNBOUND_WORKQUEUE, /* poll from unbound workqueue */ > + IB_POLL_LAST, > }; > > struct ib_cq { > @@ -1564,9 +1565,12 @@ struct ib_cq { > void (*event_handler)(struct ib_event *, void *); > void *cq_context; > int cqe; > + int cqe_used; > atomic_t usecnt; /* count number of work queues */ > enum ib_poll_context poll_ctx; > + int comp_vector; > struct ib_wc *wc; > + struct list_head pool_entry; > union { > struct irq_poll iop; > struct work_struct work; > @@ -2695,6 +2699,10 @@ struct ib_device { > #endif > > u32 index; > + > + spinlock_t cq_pools_lock; > + struct list_head cq_pools[IB_POLL_LAST - 1]; > + > struct rdma_restrack_root *res; > > const struct uapi_definition *driver_def; > @@ -3952,6 +3960,33 @@ static inline int ib_req_notify_cq(struct ib_cq *cq, > return cq->device->ops.req_notify_cq(cq, flags); > } > > +/* > + * ib_cq_pool_get() - Find the least used completion queue that matches > + * a given cpu hint (or least used for wild card affinity) > + * and fits nr_cqe > + * @dev: rdma device > + * @nr_cqe: number of needed cqe entries > + * @comp_vector_hint: completion vector hint (-1) for the driver to assign > + * a comp vector based on internal counter > + * @poll_ctx: cq polling context > + * > + * Finds a cq that satisfies @comp_vector_hint and @nr_cqe requirements and > + * claim entries in it for us. In case there is no available cq, allocate > + * a new cq with the requirements and add it to the device pool. > + * IB_POLL_DIRECT cannot be used for shared cqs so it is not a valid value > + * for @poll_ctx. > + */ > +struct ib_cq *ib_cq_pool_get(struct ib_device *dev, unsigned int nr_cqe, > + int comp_vector_hint, > + enum ib_poll_context poll_ctx); > + > +/** > + * ib_cq_pool_put - Return a CQ taken from a shared pool. > + * @cq: The CQ to return. > + * @nr_cqe: The max number of cqes that the user had requested. > + */ > +void ib_cq_pool_put(struct ib_cq *cq, unsigned int nr_cqe); > + > /** > * ib_req_ncomp_notif - Request completion notification when there are > * at least the specified number of unreaped completions on the CQ.