52 lines
2.4 KiB
ReStructuredText
52 lines
2.4 KiB
ReStructuredText
|
.. _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.
|