[PATCH V3 1/2] IB/core: Add support for enhanced atomic operations

Vladimir Sokolovsky
2010-03-10T15:58:13Z

- Add a new IB_WR_MASKED_ATOMIC_CMP_AND_SWP and IB_WR_MASKED_ATOMIC_FETCH_AND_ADD send
opcodes that can be used to mark a "masked atomic compare and swap" and
"masked atomic fetch and add" work request correspondingly.
- Add IB_DEVICE_MASKED_ATOMIC capability bit.
- Add mask fields to atomic struct of ib_send_wr
- Add new opcodes to ib_wc_opcode

Masked Compare and Swap (MskCmpSwap)
The MskCmpSwap atomic operation is an extension to the CmpSwap operation
defined in the IB spec. MskCmpSwap allows the user to select a portion of the
64 bit target data for the “compare” check as well as to restrict the swap to a
(possibly different) portion. The pseudo code below describes the operation:

| atomic_response = *va
| if (!((compare_add ^ *va) & compare_add_mask)) then
| *va = (*va & ~(swap_mask)) | (swap & swap_mask)
|
| return atomic_response

The additional operands are carried in the Extended Transport Header. Atomic
response generation and packet format for MskCmpSwap is as for standard IB
Atomic operations.

Masked Fetch and Add (MFetchAdd)
The MFetchAdd Atomic operation extends the functionality of the standard IB
FetchAdd by allowing the user to split the target into multiple fields of
selectable length. The atomic add is done independently on each one of this
fields. A bit set in the field_boundary parameter specifies the field
boundaries. The pseudo code below describes the operation:

| bit_adder(ci, b1, b2, *co)
| {
| value = ci + b1 + b2
| *co = !!(value & 2)
|
| return value & 1
| }
|
| #define MASK_IS_SET(mask, attr) (!!((mask)&(attr)))
| bit_position = 1
| carry = 0
| atomic_response = 0
|
| for i = 0 to 63
| {
| if ( i != 0 )
| bit_position = bit_position << 1
|
| bit_add_res = bit_adder(carry, MASK_IS_SET(*va, bit_position), MASK_IS_SET(compare_add, bit_position), &new_carry)
| if (bit_add_res)
| atomic_response |= bit_position
|
| carry = ((new_carry) && (!MASK_IS_SET(compare_add_mask, bit_position)))
| }
|
| return atomic_response

Signed-off-by: Vladimir Sokolovsky <vlad-VPRAkNaXOzVS1MOuV/RT9w@public.gmane.org>
---
include/rdma/ib_verbs.h | 7 +++++++
1 files changed, 7 insertions(+), 0 deletions(-)

diff --git a/include/rdma/ib_verbs.h b/include/rdma/ib_verbs.h
index 09509ed..53b16a6 100644
--- a/include/rdma/ib_verbs.h
+++ b/include/rdma/ib_verbs.h
@@ -105,6 +105,7 @@ enum ib_device_cap_flags {
IB_DEVICE_UD_TSO = (1<<19),
IB_DEVICE_MEM_MGT_EXTENSIONS = (1<<21),
IB_DEVICE_BLOCK_MULTICAST_LOOPBACK = (1<<22),
+ IB_DEVICE_MASKED_ATOMIC = (1<<23),
};

enum ib_atomic_cap {
@@ -467,6 +468,8 @@ enum ib_wc_opcode {
IB_WC_LSO,
IB_WC_LOCAL_INV,
IB_WC_FAST_REG_MR,
+ IB_WC_MASKED_COMP_SWAP,
+ IB_WC_MASKED_FETCH_ADD,
/*
* Set value of IB_WC_RECV so consumers can test if a completion is a
* receive by testing (opcode & IB_WC_RECV).
@@ -689,6 +692,8 @@ enum ib_wr_opcode {
IB_WR_RDMA_READ_WITH_INV,
IB_WR_LOCAL_INV,
IB_WR_FAST_REG_MR,
+ IB_WR_MASKED_ATOMIC_CMP_AND_SWP,
+ IB_WR_MASKED_ATOMIC_FETCH_AND_ADD,
};

enum ib_send_flags {
@@ -731,6 +736,8 @@ struct ib_send_wr {
u64 remote_addr;
u64 compare_add;
u64 swap;
+ u64 compare_add_mask;
+ u64 swap_mask;
u32 rkey;
} atomic;
struct {
--
1.6.6.GIT

--
To unsubscribe from this list: send the line "unsubscribe linux-rdma" in
the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
More majordomo info at http://vger.kernel.org/majordomo-info.html