freebsd-nq/sys/dev/ipmi
Jonathan T. Looney 1524298754 The current IPMI KCS code is waiting 100us for all transitions (roughly
between each byte either sent or received). However, most transitions
actually complete in 2-3 microseconds.

By polling the status register with a delay of 4us with exponential
backoff, the performance of most IPMI operations is significantly
improved:
  - A BMC update on a Supermicro x9 or x11 motherboard goes from ~1 hour
    to ~6-8 minutes.
  - An ipmitool sensor list time improves by a factor of 4.

Testing showed no significant improvements on a modern server by using
a lower delay.

The changes should also generally reduce the total amount of CPU or
I/O bandwidth used for a given IPMI operation.

Submitted by:	Loic Prylli <lprylli@netflix.com>
Reviewed by:	jhb
MFC after:	2 weeks
Sponsored by:	Netflix
Differential Revision:	https://reviews.freebsd.org/D20527
2019-06-12 16:06:31 +00:00
..
ipmi_acpi.c Distinguish _CID match and _HID match and make lower priority probe 2018-10-26 00:05:46 +00:00
ipmi_isa.c sys/dev: further adoption of SPDX licensing ID tags. 2017-11-27 14:52:40 +00:00
ipmi_kcs.c The current IPMI KCS code is waiting 100us for all transitions (roughly 2019-06-12 16:06:31 +00:00
ipmi_linux.c sys/dev: further adoption of SPDX licensing ID tags. 2017-11-27 14:52:40 +00:00
ipmi_opal.c Extract eventfilter declarations to sys/_eventfilter.h 2019-05-20 00:38:23 +00:00
ipmi_pci.c sys/dev: further adoption of SPDX licensing ID tags. 2017-11-27 14:52:40 +00:00
ipmi_smbios.c sys/dev: further adoption of SPDX licensing ID tags. 2017-11-27 14:52:40 +00:00
ipmi_smbus.c sys/dev: further adoption of SPDX licensing ID tags. 2017-11-27 14:52:40 +00:00
ipmi_smic.c sys/dev: further adoption of SPDX licensing ID tags. 2017-11-27 14:52:40 +00:00
ipmi_ssif.c sys/dev: further adoption of SPDX licensing ID tags. 2017-11-27 14:52:40 +00:00
ipmi.c Extract eventfilter declarations to sys/_eventfilter.h 2019-05-20 00:38:23 +00:00
ipmivars.h sys/dev: further adoption of SPDX licensing ID tags. 2017-11-27 14:52:40 +00:00