gfx9_waitcnt.rst 2.96 KB

waitcnt

Counts of outstanding instructions to wait for.

The bits of this operand have the following meaning:

High Bits Low Bits Description Value Range
15:14 3:0 VM_CNT: vector memory operations count. 0..63
- 6:4 EXP_CNT: export count. 0..7
- 11:8 LGKM_CNT: LDS, GDS, Constant and Message count. 0..15

This operand may be specified as one of the following:

  • An :ref:`integer_number<amdgpu_synid_integer_number>` or an :ref:`absolute_expression<amdgpu_synid_absolute_expression>`. The value must be in the range 0..0xFFFF.

  • A combination of vmcnt, expcnt, lgkmcnt and other values described below.

    Syntax

    Description

    vmcnt(<N>)

    A VM_CNT value. N must not exceed the largest VM_CNT value.

    expcnt(<N>)

    An EXP_CNT value. N must not exceed the largest EXP_CNT value.

    lgkmcnt(<N>)

    An LGKM_CNT value. N must not exceed the largest LGKM_CNT value.

    vmcnt_sat(<N>)

    A VM_CNT value computed as min(N, the largest VM_CNT value).

    expcnt_sat(<N>)

    An EXP_CNT value computed as min(N, the largest EXP_CNT value).

    lgkmcnt_sat(<N>)

    An LGKM_CNT value computed as min(N, the largest LGKM_CNT value).

These values may be specified in any order. Spaces, ampersands and commas may be used as optional separators.

N is either an :ref:`integer number<amdgpu_synid_integer_number>` or an :ref:`absolute expression<amdgpu_synid_absolute_expression>`.

Examples:

vm_cnt = 1
exp_cnt = 2
lgkm_cnt = 3
cnt = vm_cnt | (exp_cnt << 4) | (lgkm_cnt << 8)

s_waitcnt cnt
s_waitcnt 1 | (2 << 4) | (3 << 8)                          // the same as above
s_waitcnt vmcnt(1) expcnt(2) lgkmcnt(3)                    // the same as above
s_waitcnt vmcnt(vm_cnt) expcnt(exp_cnt) lgkmcnt(lgkm_cnt)  // the same as above

s_waitcnt vmcnt(1)
s_waitcnt expcnt(2) lgkmcnt(3)
s_waitcnt vmcnt(1), expcnt(2), lgkmcnt(3)
s_waitcnt vmcnt(1) & lgkmcnt_sat(100) & expcnt(2)