Ticket 3986

Summary:	Updated hwloc behavior breaks slurm cpu bind
Product:	Slurm	Reporter:	peter.georg
Component:	KNL	Assignee:	Jacob Jenson <jacob>
Status:	RESOLVED INVALID	QA Contact:
Severity:	6 - No support contract
Priority:	---
Version:	17.02.5
Hardware:	Linux
OS:	Linux
Site:	-Other-	Alineos Sites:	---
Atos/Eviden Sites:	---	Confidential Site:	---
Coreweave sites:	---	Cray Sites:	---
DS9 clusters:	---	HPCnow Sites:	---
HPE Sites:	---	IBM Sites:	---
NOAA SIte:	---	OCF Sites:	---
Recursion Pharma Sites:	---	SFW Sites:	---
SNIC sites:	---	Linux Distro:	---
Machine Name:		CLE Version:
Version Fixed:		Target Release:	---
DevPrio:	---	Emory-Cloud Sites:	---
Attachments:	Proposed patch

Description peter.georg 2017-07-12 04:53:01 MDT

Created attachment 4905 [details]
Proposed patch

Hi,

An updated version of hwloc (provided by Intel in xppsl >= 1.5.1) changes the behavior of some functions. This change of behavior causes Slurm to, at least for KNL configured as SNC4 + Flat, bind processes to the wrong cores/hwthreads.
See https://software.intel.com/en-us/forums/intel-many-integrated-core/topic/737918#comment-1908677 for more details.

Currently we are using Slurm 17.02.5, however 16.05.x (and most likely 17.11.x) is affected as well.

See attached a proposed patch that *should* work for both the old and new hwloc behavior. This patch adds a slight overhead (only executed once) as it re-checks the number of cpus per socket.

Best,

peter