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authorBart Van Assche <bvanassche@acm.org>2014-10-06 17:14:36 +0200
committerChristoph Hellwig <hch@lst.de>2014-11-12 12:05:24 +0100
commitd92c0da71a35dfddccca7bfa932829504311359e (patch)
tree84b87ede947430e8b53b33bf99c349c99243cb9d /Documentation/ABI
parent77f2c1a40e6fed202d08c8ec0bdca36a76dab368 (diff)
IB/srp: Add multichannel support
Improve performance by using multiple RDMA/RC channels per SCSI host for communication with an SRP target. About the implementation: - Introduce a loop over all channels in the code that uses target->ch. - Set the SRP_MULTICHAN_MULTI flag during login for the creation of the second and subsequent channels. - RDMA completion vectors are chosen such that RDMA completion interrupts are handled by the CPU socket that submitted the I/O request. As one can see in this patch it has been assumed if a system contains n CPU sockets and m RDMA completion vectors have been assigned to an RDMA HCA that IRQ affinity has been configured such that completion vectors [i*m/n..(i+1)*m/n) are bound to CPU socket i with 0 <= i < n. - Modify srp_free_ch_ib() and srp_free_req_data() such that it becomes safe to invoke these functions after the corresponding allocation function failed. - Add a ch_count sysfs attribute per target port. Signed-off-by: Bart Van Assche <bvanassche@acm.org> Reviewed-by: Sagi Grimberg <sagig@mellanox.com> Signed-off-by: Christoph Hellwig <hch@lst.de>
Diffstat (limited to 'Documentation/ABI')
-rw-r--r--Documentation/ABI/stable/sysfs-driver-ib_srp25
1 files changed, 19 insertions, 6 deletions
diff --git a/Documentation/ABI/stable/sysfs-driver-ib_srp b/Documentation/ABI/stable/sysfs-driver-ib_srp
index b9688de8455b..7049a2b50359 100644
--- a/Documentation/ABI/stable/sysfs-driver-ib_srp
+++ b/Documentation/ABI/stable/sysfs-driver-ib_srp
@@ -55,12 +55,12 @@ Description: Interface for making ib_srp connect to a new target.
only safe with partial memory descriptor list support enabled
(allow_ext_sg=1).
* comp_vector, a number in the range 0..n-1 specifying the
- MSI-X completion vector. Some HCA's allocate multiple (n)
- MSI-X vectors per HCA port. If the IRQ affinity masks of
- these interrupts have been configured such that each MSI-X
- interrupt is handled by a different CPU then the comp_vector
- parameter can be used to spread the SRP completion workload
- over multiple CPU's.
+ MSI-X completion vector of the first RDMA channel. Some
+ HCA's allocate multiple (n) MSI-X vectors per HCA port. If
+ the IRQ affinity masks of these interrupts have been
+ configured such that each MSI-X interrupt is handled by a
+ different CPU then the comp_vector parameter can be used to
+ spread the SRP completion workload over multiple CPU's.
* tl_retry_count, a number in the range 2..7 specifying the
IB RC retry count.
* queue_size, the maximum number of commands that the
@@ -88,6 +88,13 @@ Description: Whether ib_srp is allowed to include a partial memory
descriptor list in an SRP_CMD when communicating with an SRP
target.
+What: /sys/class/scsi_host/host<n>/ch_count
+Date: April 1, 2015
+KernelVersion: 3.19
+Contact: linux-rdma@vger.kernel.org
+Description: Number of RDMA channels used for communication with the SRP
+ target.
+
What: /sys/class/scsi_host/host<n>/cmd_sg_entries
Date: May 19, 2011
KernelVersion: 2.6.39
@@ -95,6 +102,12 @@ Contact: linux-rdma@vger.kernel.org
Description: Maximum number of data buffer descriptors that may be sent to
the target in a single SRP_CMD request.
+What: /sys/class/scsi_host/host<n>/comp_vector
+Date: September 2, 2013
+KernelVersion: 3.11
+Contact: linux-rdma@vger.kernel.org
+Description: Completion vector used for the first RDMA channel.
+
What: /sys/class/scsi_host/host<n>/dgid
Date: June 17, 2006
KernelVersion: 2.6.17

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