Ubuntu
linux package

[22.10 FEAT] Enablement for MIO Instructions - kernel part

Bug #1959543 reported by bugproxy
16
This bug affects 2 people
Affects Status Importance Assigned to Milestone
Ubuntu on IBM z Systems
Fix Released
High
Skipper Bug Screeners
linux (Ubuntu)
Fix Released
High
Unassigned
Jammy
Fix Released
High
Unassigned
Kinetic
Fix Released
High
Unassigned

Bug Description

Enablement for MIO Instructions - kernel part

Feature Description

Make use of the new PCI Load/Store instructions in the rdma-core package.

The existing support for rdma-core uses the privileged functions for RDMA traffic, which rely on add'l syscalls. Though syscalls on s390 are said to be not as expensive as on other platforms, it still defeats the purpose of the userspace RDMA approach, and the context switches still cost us.
Furthermore, the new instructions operate on virtual addresses instead of function handles, with Millicode handling the address translation. This is more similar to real MMIO, and allows for real re-mapping..

bugproxy (bugproxy)
tags: added: architecture-s39064 bugnameltc-196211 severity-high targetmilestone-inin2204
Changed in ubuntu:
assignee: nobody → Skipper Bug Screeners (skipper-screen-team)
affects: ubuntu → linux (Ubuntu)
Revision history for this message
bugproxy (bugproxy) wrote : Comment bridged from LTC Bugzilla

------- Comment From <email address hidden> 2022-01-30 22:14 EDT-------
This also has a rdma-core part:
Canonical LP#1959544 - IBM BZ#196212 [22.04 FEAT] Enablement for MIO Instructions - rdma-core part

Revision history for this message
Frank Heimes (fheimes) wrote : Re: [22.04 FEAT] Enablement for MIO Instructions - kernel part

Updating ticket to Incomplete until the required commits for this are known (guess they are upstream in 5.16 or 5.17?)

Changed in ubuntu-z-systems:
assignee: nobody → Skipper Bug Screeners (skipper-screen-team)
Changed in linux (Ubuntu):
importance: Undecided → High
Changed in ubuntu-z-systems:
importance: Undecided → High
Changed in linux (Ubuntu):
status: New → Incomplete
Changed in ubuntu-z-systems:
status: New → Incomplete
Revision history for this message
bugproxy (bugproxy) wrote : Comment bridged from LTC Bugzilla

------- Comment From <email address hidden> 2022-03-15 07:05 EDT-------
Item doesn't make it into jammy / 22.04, therefore moving to 22.10
Changing target milestone from 22.04 ==> 22.10

tags: added: targetmilestone-inin2210
removed: targetmilestone-inin2204
Frank Heimes (fheimes)
summary: - [22.04 FEAT] Enablement for MIO Instructions - kernel part
+ [22.10 FEAT] Enablement for MIO Instructions - kernel part
Revision history for this message
bugproxy (bugproxy) wrote :

------- Comment From <email address hidden> 2022-07-26 20:07 EDT-------
The two kernel patches for this feature have been included in kernel 5.15.

Summary: s390: add HWCAP_S390_PCI_MIO to ELF hwcaps
Upstream-ID: 7e8403ecaf884f307b627f3c371475913dd29292

Summary: s390: add HWCAP_S390_PCI_MIO to ELF hwcaps
Upstream-ID: 3322ba0d7bea1e24ae464418626f6a15b69533ab

Revision history for this message
Frank Heimes (fheimes) wrote :

I can confirm that these two patches are incl. in 22.04/jammy:
7e8403ecaf884f307b627f3c371475913dd29292 "s390: add HWCAP_S390_PCI_MIO to ELF hwcaps"
3322ba0d7bea1e24ae464418626f6a15b69533ab "s390: make PCI mio support a machine flag"
(but the 2nd one has a different name)

With that updating the status for jammy as well as for kinetic to Fix Released.

Changed in linux (Ubuntu Kinetic):
assignee: Skipper Bug Screeners (skipper-screen-team) → nobody
Changed in linux (Ubuntu Jammy):
importance: Undecided → High
Changed in linux (Ubuntu Kinetic):
status: Incomplete → Fix Released
Changed in linux (Ubuntu Jammy):
status: New → Fix Released
Changed in ubuntu-z-systems:
status: Incomplete → Fix Released
information type: Private → Public
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