Re: [PATCH v4 for-next 3/3] IB/core: Obtain subnet_prefix from cache in IB devices
From: Anand Khoje
Date: Wed Jun 16 2021 - 03:43:11 EST
On 6/16/2021 12:57 PM, Leon Romanovsky wrote:
On Wed, Jun 16, 2021 at 12:22:13PM +0530, Anand Khoje wrote:
ib_query_port() calls device->ops.query_port() to get the port
attributes. The method of querying is device driver specific.
The same function calls device->ops.query_gid() to get the GID and
extract the subnet_prefix (gid_prefix).
The GID and subnet_prefix are stored in a cache. But they do not get
read from the cache if the device is an Infiniband device. The
following change takes advantage of the cached subnet_prefix.
Testing with RDBMS has shown a significant improvement in performance
with this change.
The function ib_cache_is_initialised() is introduced because
ib_query_port() gets called early in the stage when the cache is not
built while reading port immutable property.
In that case, the default GID still gets read from HCA for IB link-
layer devices.
In the situation of an event causing cache update, the subnet_prefix
will get retrieved from newly updated GID cache in ib_cache_update(),
so that we do not end up reading a stale value from cache via
ib_query_port().
Fixes: fad61ad ("IB/core: Add subnet prefix to port info")
Suggested-by: Leon Romanovsky <leonro@xxxxxxxxxx>
Suggested-by: Aru Kolappan <aru.kolappan@xxxxxxxxxx>
Signed-off-by: Anand Khoje <anand.a.khoje@xxxxxxxxxx>
Signed-off-by: Haakon Bugge <haakon.bugge@xxxxxxxxxx>
---
v1 -> v2:
- Split the v1 patch in 3 patches as per Leon's suggestion.
v2 -> v3:
- Added changes as per Mark Zhang's suggestion of clearing
flags in git_table_cleanup_one().
v3 -> v4:
- Removed the enum ib_port_data_flags and 8 byte flags from
struct ib_port_data, and the set_bit()/clear_bit() API
used to update this flag as that was not necessary.
Done to keep the code simple.
- Added code to read subnet_prefix from updated GID cache in the
event of cache update. Prior to this change, ib_cache_update
was reading the value for subnet_prefix via ib_query_port(),
due to this patch, we ended up reading a stale cached value of
subnet_prefix.
---
drivers/infiniband/core/cache.c | 18 +++++++++++++++---
drivers/infiniband/core/device.c | 9 +++++++++
include/rdma/ib_cache.h | 5 +++++
include/rdma/ib_verbs.h | 1 +
4 files changed, 30 insertions(+), 3 deletions(-)
diff --git a/drivers/infiniband/core/cache.c b/drivers/infiniband/core/cache.c
index 2325171..cd99c46 100644
--- a/drivers/infiniband/core/cache.c
+++ b/drivers/infiniband/core/cache.c
@@ -917,9 +917,11 @@ static void gid_table_cleanup_one(struct ib_device *ib_dev)
{
u32 p;
- rdma_for_each_port (ib_dev, p)
+ rdma_for_each_port (ib_dev, p) {
+ ib_dev->port_data[p].cache_is_initialized = 0;
I think that this line is not needed, we are removing device anyway and
and query_port is not allowed at this stage.
We have kept this for code completeness purposes. Just as we did with
set_bit() and clear_bit() APIs.
cleanup_gid_table_port(ib_dev, p,
ib_dev->port_data[p].cache.gid);
+ }
}
static int gid_table_setup_one(struct ib_device *ib_dev)
@@ -1466,6 +1468,7 @@ static int config_non_roce_gid_cache(struct ib_device *device,
struct ib_port_attr *tprops = NULL;
struct ib_pkey_cache *pkey_cache = NULL;
struct ib_pkey_cache *old_pkey_cache = NULL;
+ union ib_gid gid;
int i;
int ret;
@@ -1523,13 +1526,21 @@ static int config_non_roce_gid_cache(struct ib_device *device,
device->port_data[port].cache.lmc = tprops->lmc;
device->port_data[port].cache.port_state = tprops->state;
- device->port_data[port].cache.subnet_prefix = tprops->subnet_prefix;
+ ret = rdma_query_gid(device, port, 0, &gid);
+ if (ret) {
+ write_unlock_irq(&device->cache.lock);
+ goto err;
+ }
+
+ device->port_data[port].cache.subnet_prefix =
+ be64_to_cpu(gid.global.subnet_prefix);
+
write_unlock_irq(&device->cache_lock);
if (enforce_security)
ib_security_cache_change(device,
port,
- tprops->subnet_prefix);
+ be64_to_cpu(gid.global.subnet_prefix));
kfree(old_pkey_cache);
kfree(tprops);
@@ -1629,6 +1640,7 @@ int ib_cache_setup_one(struct ib_device *device)
err = ib_cache_update(device, p, true, true, true);
if (err)
return err;
+ device->port_data[p].cache_is_initialized = 1;
}
return 0;
diff --git a/drivers/infiniband/core/device.c b/drivers/infiniband/core/device.c
index 7a617e4..57b9039 100644
--- a/drivers/infiniband/core/device.c
+++ b/drivers/infiniband/core/device.c
@@ -2057,6 +2057,15 @@ static int __ib_query_port(struct ib_device *device,
IB_LINK_LAYER_INFINIBAND)
return 0;
+ if (!ib_cache_is_initialised(device, port_num))
+ goto query_gid_from_device;
IMHO, we don't need this new function and can access ib_port_data
directly. In device.c, we have plenty of places that does it.
Not critical.
Added this function to have a way to check validity of cache, such that
it could be used in future for the same check in areas to which
ib_port_data is opaque.
+
+ ib_get_cached_subnet_prefix(device, port_num,
+ &port_attr->subnet_prefix);
+
+ return 0;
+
+query_gid_from_device:
err = device->ops.query_gid(device, port_num, 0, &gid);
if (err)
return err;
diff --git a/include/rdma/ib_cache.h b/include/rdma/ib_cache.h
index 226ae37..46b43a7 100644
--- a/include/rdma/ib_cache.h
+++ b/include/rdma/ib_cache.h
@@ -114,4 +114,9 @@ ssize_t rdma_query_gid_table(struct ib_device *device,
struct ib_uverbs_gid_entry *entries,
size_t max_entries);
+static inline bool ib_cache_is_initialised(struct ib_device *device,
+ u32 port_num)
+{
+ return device->port_data[port_num].cache_is_initialized;
+}
#endif /* _IB_CACHE_H */
diff --git a/include/rdma/ib_verbs.h b/include/rdma/ib_verbs.h
index c96d601..405f7da 100644
--- a/include/rdma/ib_verbs.h
+++ b/include/rdma/ib_verbs.h
@@ -2177,6 +2177,7 @@ struct ib_port_data {
spinlock_t netdev_lock;
+ u8 cache_is_initialized:1;
struct list_head pkey_list;
struct ib_port_cache cache;
--
1.8.3.1