From: Patrick Kelsey pat.kelsey@cornelisnetworks.com
[ Upstream commit 9fe8fec5e43d5a80f43cbf61aaada1b047a1eb61 ]
hfi1_mmu_rb_remove_unless_exact() did not move mmu_rb_node objects in mmu_rb_handler->lru_list after getting a cache hit on an mmu_rb_node.
As a result, hfi1_mmu_rb_evict() was not guaranteed to evict truly least-recently used nodes.
This could be a performance issue for an application when that application: - Uses some long-lived buffers frequently. - Uses a large number of buffers once. - Hits the mmu_rb_handler cache size or pinned-page limits, forcing mmu_rb_handler cache entries to be evicted.
In this case, the one-time use buffers cause the long-lived buffer entries to eventually filter to the end of the LRU list where hfi1_mmu_rb_evict() will consider evicting a frequently-used long-lived entry instead of evicting one of the one-time use entries.
Fix this by inserting new mmu_rb_node at the tail of mmu_rb_handler->lru_list and move mmu_rb_ndoe to the tail of mmu_rb_handler->lru_list when the mmu_rb_node is a hit in hfi1_mmu_rb_remove_unless_exact(). Change hfi1_mmu_rb_evict() to evict from the head of mmu_rb_handler->lru_list instead of the tail.
Fixes: 0636e9ab8355 ("IB/hfi1: Add cache evict LRU list") Signed-off-by: Brendan Cunningham bcunningham@cornelisnetworks.com Signed-off-by: Patrick Kelsey pat.kelsey@cornelisnetworks.com Signed-off-by: Dennis Dalessandro dennis.dalessandro@cornelisnetworks.com Link: https://lore.kernel.org/r/168088635931.3027109.10423156330761536044.stgit@25... Signed-off-by: Leon Romanovsky leon@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/infiniband/hw/hfi1/mmu_rb.c | 13 ++++++------- 1 file changed, 6 insertions(+), 7 deletions(-)
diff --git a/drivers/infiniband/hw/hfi1/mmu_rb.c b/drivers/infiniband/hw/hfi1/mmu_rb.c index 175002c046ede..42eddaf3a9947 100644 --- a/drivers/infiniband/hw/hfi1/mmu_rb.c +++ b/drivers/infiniband/hw/hfi1/mmu_rb.c @@ -177,7 +177,7 @@ int hfi1_mmu_rb_insert(struct mmu_rb_handler *handler, goto unlock; } __mmu_int_rb_insert(mnode, &handler->root); - list_add(&mnode->list, &handler->lru_list); + list_add_tail(&mnode->list, &handler->lru_list);
ret = handler->ops->insert(handler->ops_arg, mnode); if (ret) { @@ -224,8 +224,10 @@ bool hfi1_mmu_rb_remove_unless_exact(struct mmu_rb_handler *handler, spin_lock_irqsave(&handler->lock, flags); node = __mmu_rb_search(handler, addr, len); if (node) { - if (node->addr == addr && node->len == len) + if (node->addr == addr && node->len == len) { + list_move_tail(&node->list, &handler->lru_list); goto unlock; + } __mmu_int_rb_remove(node, &handler->root); list_del(&node->list); /* remove from LRU list */ ret = true; @@ -246,8 +248,7 @@ void hfi1_mmu_rb_evict(struct mmu_rb_handler *handler, void *evict_arg) INIT_LIST_HEAD(&del_list);
spin_lock_irqsave(&handler->lock, flags); - list_for_each_entry_safe_reverse(rbnode, ptr, &handler->lru_list, - list) { + list_for_each_entry_safe(rbnode, ptr, &handler->lru_list, list) { if (handler->ops->evict(handler->ops_arg, rbnode, evict_arg, &stop)) { __mmu_int_rb_remove(rbnode, &handler->root); @@ -259,9 +260,7 @@ void hfi1_mmu_rb_evict(struct mmu_rb_handler *handler, void *evict_arg) } spin_unlock_irqrestore(&handler->lock, flags);
- while (!list_empty(&del_list)) { - rbnode = list_first_entry(&del_list, struct mmu_rb_node, list); - list_del(&rbnode->list); + list_for_each_entry_safe(rbnode, ptr, &del_list, list) { handler->ops->remove(handler->ops_arg, rbnode); } }