| .. _skiboot-6.0.6: |
| |
| ============= |
| skiboot-6.0.6 |
| ============= |
| |
| skiboot 6.0.6 was released on Thursday July 19th, 2018. It replaces |
| :ref:`skiboot-6.0.5` as the current stable release in the 6.0.x series. |
| |
| It is recommended that 6.0.5 be used instead of any previous 6.0.x version, |
| especially in the case where NVLINK2 GPUs and/or Mellanox CX5 adapters are |
| being used. |
| |
| Over :ref:`skiboot-6.0.5` we have several important performance related bug |
| fixes and one stability bug fix: |
| |
| - phb4/CAPI: Reallocate PEC2 DMA-Read engines to improve GPU-Direct bandwidth |
| |
| We reallocate additional 16/8 DMA-Read engines allocated to stack0/1 |
| on PEC2 respectively. This is needed to improve bandwidth available to |
| the Mellanox CX5 adapter when trying to read GPU memory (GPU-Direct). |
| |
| If kernel cxl driver indicates a request to allocate maximum possible |
| DMA read engines when calling enable_capi_mode() and card is attached |
| to PEC2/stack0 slot then we assume its a Mellanox CX5 adapter. We then |
| allocate additional 16/8 extra DMA read engines to stack0 and stack1 |
| respectively on PEC2. This is done by populating the |
| XPEC_PCI_PRDSTKOVR and XPEC_NEST_READ_STACK_OVERRIDE as suggested by |
| the h/w team. |
| - phb4: Disable nodal scoped DMA accesses when PB pump mode is enabled |
| |
| By default when a PCIe device issues a read request via the PHB it is first |
| issued with nodal scope. When accessing GPU memory the NPU does not know at the |
| time of response if the requested memory page is off node or not. Therefore |
| every read of GPU memory by a PHB is retried with larger scope which introduces |
| bandwidth and latency issues. |
| |
| On smaller boxes which have pump mode enabled nodal and group scoped reads are |
| treated the same and both types of request are broadcast to one chip. Therefore |
| we can avoid the retry by disabling nodal scope on the PHB for these boxes. On |
| larger boxes nodal (single chip) and group (multiple chip) scoped reads are |
| treated differently. Therefore we avoid disabling nodal scope on large boxes |
| which have pump mode disabled to avoid all PHB requests being broadcast to |
| multiple chips. |
| - npu2/hw-procedures: Enable parity and credit overflow checks |
| |
| Enable these error checking features by setting the appropriate bits in |
| our one-off initialization of each "NTL Misc Config 2" register. |
| |
| The exception is NDL RX parity checking, which should be disabled during |
| the link training procedures. |