Lars Marowsky-Brée and Bruce Walker led a brief and uncontroversial session
on clustering. There was a clustering summit happening simultaneously with
the kernel summit; not much information was yet available from that
meeting. There had been another summit two weeks before, held in Germany.
A couple of issues from that gathering were brought to the kernel summit.
One of those was dealing with memory pressure, which can be an acute
problem in clusters. Lars noted, with obvious amusement, that this problem
had been "solved" in prior kernel summit discussions.
A longstanding question for cluster developers has been: how much work
needs to be done in the kernel, and how much can be pushed out to user
space? Answers are becoming clearer: cluster configuration and node
membership tasks are now clearly user space issues. Distributed lock
management appears to be a kernel task, however.
Along those lines, it was briefly noted that the OCFS2 filesystem group is
considering dropping its lock manager implementation in favor of Red Hat's
One issue still in need of resolution is cluster-wide process management.
There are currently about five different process management implementations
out there. Bruce, who works with the OpenSSI project, floated a proposal which
would add a set of hooks to the kernel. Users could then employ the
process manager of their choice by way of those hooks. The kernel
developers have little patience for the addition of more general-purpose
hooks, however; they would rather see people bite the bullet and choose a
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