Re: [Linuxptp-users] Intel i350 offset volatility

[Aris T. <ar...@ma...>]

For the record, I adjusted some kernel configurations and the offsets are now down to the ~20-30 ns range on the i350 card.

The differences are adjustments to PCI bus performance modes.

Aris


Previous kernel (5.19.0-2-rt-amd64) - had large swings in offsets:

< CONFIG_CC_VERSION_TEXT="gcc-11 (Debian 11.3.0-6) 11.3.0"
< CONFIG_GCC_VERSION=110300
< CONFIG_AS_VERSION=23890
< CONFIG_LD_VERSION=23890
< CONFIG_PCIEASPM_DEFAULT=y
< # CONFIG_PCIEASPM_PERFORMANCE is not set
< CONFIG_PCIE_BUS_DEFAULT=y
< # CONFIG_PCIE_BUS_PERFORMANCE is not set
< CONFIG_PPS=m
< CONFIG_PTP_1588_CLOCK=m
< CONFIG_PTP_1588_CLOCK_OPTIONAL=m


New kernel (5.19.11-rt9-amd64) - now offsets are behaving as expected (generally low 20-30ns offsets observed across all i350 ports):

> CONFIG_CC_VERSION_TEXT="gcc (Debian 12.2.0-3) 12.2.0"
> CONFIG_GCC_VERSION=120200
> CONFIG_AS_VERSION=23900
> CONFIG_LD_VERSION=23900
> CONFIG_BUILD_SALT=""
> CONFIG_CC_NO_ARRAY_BOUNDS=y
> CONFIG_MODULE_SIG_ALL=y
> # CONFIG_PCIEASPM_DEFAULT is not set
> CONFIG_PCIEASPM_PERFORMANCE=y
> # CONFIG_PCIE_BUS_DEFAULT is not set
> CONFIG_PCIE_BUS_PERFORMANCE=y
> CONFIG_PPS=y
> CONFIG_PTP_1588_CLOCK=y
> CONFIG_PTP_1588_CLOCK_OPTIONAL=y
> CONFIG_CC_HAS_AUTO_VAR_INIT_PATTERN=y
> CONFIG_CC_HAS_AUTO_VAR_INIT_ZERO=y