linux-kernel - [PATCH 0/3] powerpc: Enable dynamic preemption

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Message-ID: <20241125042212.1522315-1-sshegde@linux.ibm.com>
Date: Mon, 25 Nov 2024 09:52:09 +0530
From: Shrikanth Hegde <sshegde@...ux.ibm.com>
To: mpe@...erman.id.au, linuxppc-dev@...ts.ozlabs.org
Cc: sshegde@...ux.ibm.com, npiggin@...il.com, christophe.leroy@...roup.eu,
        maddy@...ux.ibm.com, bigeasy@...utronix.de, ankur.a.arora@...cle.com,
        linux-kernel@...r.kernel.org, mark.rutland@....com,
        vschneid@...hat.com, peterz@...radead.org
Subject: [PATCH 0/3] powerpc: Enable dynamic preemption

Once the lazy preemption is supported, it makes sense to enable dynamic
preemption. One can change the preemption model without changing the
kernel. 

Overheads of dynamic preemption seems reasonable for some of the
workloads. Tested with db2 database workload, unixbench, schbench
and hackbench. Except hackbench pipe rest show similar numbers as
without dynamic preemption specially for preempt=none. 

These patches *depend* on lazy preemption patches[1] to be applied
first on tip/sched/core tree. 

The reason for arch/asm/preempt.h is to enable arch specific preempt
enablements. Also, there is plan to move preempt count to paca for 64
bit systems as idea was discussed in [2]

[1] https://lore.kernel.org/all/20241116192306.88217-1-sshegde@linux.ibm.com/#t 
[2] https://lore.kernel.org/all/14d4584d-a087-4674-9e2b-810e96078b3a@linux.ibm.com/ 

Shrikanth Hegde (3):
  powerpc: copy preempt.h into arch/include/asm
  powerpc: support dynamic preemption
  powerpc: print right preemption model in die

 arch/powerpc/Kconfig               |   1 +
 arch/powerpc/include/asm/preempt.h | 101 +++++++++++++++++++++++++++++
 arch/powerpc/kernel/interrupt.c    |   6 +-
 arch/powerpc/kernel/traps.c        |   6 +-
 arch/powerpc/lib/vmx-helper.c      |   2 +-
 5 files changed, 113 insertions(+), 3 deletions(-)
 create mode 100644 arch/powerpc/include/asm/preempt.h

-- 
2.39.3