Re: [PATCH 1/4] iommu/arm-smmu-v3: Use command queue batching helpers to improve performance
From: Leizhen (ThunderTown) <hidden>
Date: 2021-08-16 04:05:43
Also in:
linux-iommu, lkml
On 2021/8/16 10:15, Leizhen (ThunderTown) wrote:
On 2021/8/14 0:45, John Garry wrote:quoted
On 13/08/2021 17:01, Robin Murphy wrote:quoted
quoted
diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c index 235f9bdaeaf223b..c81cd929047f573 100644 --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c@@ -1747,15 +1747,16 @@ static int arm_smmu_atc_inv_master(struct arm_smmu_master *master){ int i; struct arm_smmu_cmdq_ent cmd; + struct arm_smmu_cmdq_batch cmds = {};BTW, it looks like this has crossed over with John's patch removing these.It is only called from arm_smmu_disable_ats(), so not hot-path by the look for it. Or who even has ats HW ...? But it should be at least cleaned-up for consistency. Leizhen?Okay, I'll revise it. But Will already took it. So I'm not sure whether to send v2 or a separate patch.
I think I'd better post v2, otherwise I should write the same description.
In addition, I find that function arm_smmu_cmdq_build_cmd() can also be optimized
slightly, three useless instructions can be reduced.
Case 1):
void arm_smmu_cmdq_build_cmd_tst1(u64 *cmd, struct arm_smmu_cmdq_ent *ent)
{
memset(cmd, 0, 1 << CMDQ_ENT_SZ_SHIFT);
cmd[0] |= FIELD_PREP(CMDQ_0_OP, ent->opcode);
}
0000000000004608 <arm_smmu_cmdq_build_cmd_tst1>:
4608: a9007c1f stp xzr, xzr, [x0]
460c: 39400022 ldrb w2, [x1]
4610: f9400001 ldr x1, [x0]
4614: aa020021 orr x1, x1, x2
4618: f9000001 str x1, [x0]
461c: d65f03c0 ret
Case 2):
void arm_smmu_cmdq_build_cmd_tst2(u64 *cmd, struct arm_smmu_cmdq_ent *ent)
{
int i;
cmd[0] = FIELD_PREP(CMDQ_0_OP, ent->opcode);
for (i = 1; i < CMDQ_ENT_DWORDS; i++)
cmd[i] = 0;
}
0000000000004620 <arm_smmu_cmdq_build_cmd_tst2>:
4620: 39400021 ldrb w1, [x1]
4624: a9007c01 stp x1, xzr, [x0]
4628: d65f03c0 ret
462c: d503201f nop
Case 3):
void arm_smmu_cmdq_build_cmd_tst3(u64 *cmd, struct arm_smmu_cmdq_ent *ent)
{
memset(cmd, 0, 1 << CMDQ_ENT_SZ_SHIFT);
cmd[0] = FIELD_PREP(CMDQ_0_OP, ent->opcode);
}
0000000000004630 <arm_smmu_cmdq_build_cmd_tst3>:
4630: a9007c1f stp xzr, xzr, [x0]
4634: 39400021 ldrb w1, [x1]
4638: f9000001 str x1, [x0]
463c: d65f03c0 ret
quoted
Thanks, John ._______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu
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