From: Leon Romanovsky <email@example.com>
To: Anand Khoje <firstname.lastname@example.org>
Cc: email@example.com, firstname.lastname@example.org,
email@example.com, firstname.lastname@example.org, email@example.com
Subject: Re: [PATCH v5 for-next 3/3] IB/core: Obtain subnet_prefix from cache in IB devices
Date: Thu, 17 Jun 2021 09:41:47 +0300 [thread overview]
Message-ID: <YMruq7pXGcxwW1Ne@unreal> (raw)
On Wed, Jun 16, 2021 at 09:15:09PM +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
> Fixes: fad61ad ("IB/core: Add subnet prefix to port info")
> Suggested-by: Leon Romanovsky <firstname.lastname@example.org>
> Suggested-by: Aru Kolappan <email@example.com>
> Signed-off-by: Anand Khoje <firstname.lastname@example.org>
> Signed-off-by: Haakon Bugge <email@example.com>
> 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
> v4 -> v5:
> - Removed the code to reset cache_is_initialised bit from cleanup
> as per Leon's suggestion.
> - Removed ib_cache_is_initialised() function.
> drivers/infiniband/core/cache.c | 14 ++++++++++++--
> drivers/infiniband/core/device.c | 9 +++++++++
> include/rdma/ib_verbs.h | 1 +
> 3 files changed, 22 insertions(+), 2 deletions(-)
Reviewed-by: Leon Romanovsky <firstname.lastname@example.org>
next prev parent reply other threads:[~2021-06-17 6:41 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-16 15:45 [PATCH v5 for-next 0/3] IB/core: Obtaining subnet_prefix from cache in Anand Khoje
2021-06-16 15:45 ` [PATCH v5 for-next 1/3] IB/core: Removed port validity check from ib_get_cached_subnet_prefix Anand Khoje
2021-06-16 15:45 ` [PATCH v5 for-next 2/3] IB/core: Shuffle locks in ib_port_data to save memory Anand Khoje
2021-06-16 15:45 ` [PATCH v5 for-next 3/3] IB/core: Obtain subnet_prefix from cache in IB devices Anand Khoje
2021-06-17 6:41 ` Leon Romanovsky [this message]
2021-06-21 23:49 ` Jason Gunthorpe
2021-06-23 13:03 ` Anand Khoje
2021-06-24 17:54 ` Jason Gunthorpe
2021-06-25 6:03 ` Anand Khoje
2021-06-25 12:48 ` Jason Gunthorpe
2021-06-21 23:52 ` [PATCH v5 for-next 0/3] IB/core: Obtaining subnet_prefix from cache in Jason Gunthorpe
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