[OS-BUILD PATCH] [redhat] New configs in arch/powerpc

[GitLab Bridge on behalf of jeremycline]

From: Fedora Kernel Team

Hi,

As part of the ongoing rebase effort, the following configuration
options need to be reviewed.

As a reminder, the ARK configuration flow involves moving unreviewed
configuration options from the pending directory to the ark directory.
In the diff below, options are removed from the pending directory and
added to the ark hierarchy. The final options that need to be ACKed
are the files that are being added to the ark hierarchy.

If the value for a file that is added should be changed, please reply
with a better option.

CONFIG_CMDLINE:

On some platforms, there is currently no way for the boot loader to
 pass arguments to the kernel. For these platforms, you can supply
 some command-line options at build time by entering them here.  In
 most cases you will need to specify the root device here.

Symbol: CMDLINE [=]
 Type  : string
 Defined at arch/powerpc/Kconfig:882
   Prompt: Initial kernel command string
   Location:
     -> Kernel options

---

CONFIG_PPC_QUEUED_SPINLOCKS:

Say Y here to use queued spinlocks which give better scalability and
 fairness on large SMP and NUMA systems without harming single threaded
 performance.

This option is currently experimental, the code is more complex and
 less tested so it defaults to "N" for the moment.

If unsure, say "N".

Symbol: PPC_QUEUED_SPINLOCKS [=n]
 Type  : bool
 Defined at arch/powerpc/Kconfig:497
   Prompt: Queued spinlocks
   Depends on: SMP [=y]
   Location:
     -> Kernel options

---

Signed-off-by: Fedora Kernel Team 
---
 redhat/configs/common/generic/CONFIG_CMDLINE  |  1 +
 .../generic/CONFIG_PPC_QUEUED_SPINLOCKS       |  1 +
 .../pending-common/generic/CONFIG_CMDLINE     | 17 --------------
 .../generic/CONFIG_PPC_QUEUED_SPINLOCKS       | 22 -------------------
 4 files changed, 2 insertions(+), 39 deletions(-)
 create mode 100644 redhat/configs/common/generic/CONFIG_CMDLINE
 create mode 100644 redhat/configs/common/generic/CONFIG_PPC_QUEUED_SPINLOCKS
 delete mode 100644 redhat/configs/pending-common/generic/CONFIG_CMDLINE
 delete mode 100644 redhat/configs/pending-common/generic/CONFIG_PPC_QUEUED_SPINLOCKS

diff --git a/redhat/configs/common/generic/CONFIG_CMDLINE b/redhat/configs/common/generic/CONFIG_CMDLINE
new file mode 100644
index 000000000000..f3083e1e5200
--- /dev/null
+++ b/redhat/configs/common/generic/CONFIG_CMDLINE
@@ -0,0 +1 @@
+CONFIG_CMDLINE=""
diff --git a/redhat/configs/common/generic/CONFIG_PPC_QUEUED_SPINLOCKS b/redhat/configs/common/generic/CONFIG_PPC_QUEUED_SPINLOCKS
new file mode 100644
index 000000000000..f1f7e79da5c3
--- /dev/null
+++ b/redhat/configs/common/generic/CONFIG_PPC_QUEUED_SPINLOCKS
@@ -0,0 +1 @@
+# CONFIG_PPC_QUEUED_SPINLOCKS is not set
diff --git a/redhat/configs/pending-common/generic/CONFIG_CMDLINE b/redhat/configs/pending-common/generic/CONFIG_CMDLINE
deleted file mode 100644
index 10611732c5eb..000000000000
--- a/redhat/configs/pending-common/generic/CONFIG_CMDLINE
+++ /dev/null
@@ -1,17 +0,0 @@
-# CONFIG_CMDLINE:
-# 
-# On some platforms, there is currently no way for the boot loader to
-# pass arguments to the kernel. For these platforms, you can supply
-# some command-line options at build time by entering them here.  In
-# most cases you will need to specify the root device here.
-# 
-# Symbol: CMDLINE [=]
-# Type  : string
-# Defined at arch/powerpc/Kconfig:882
-#   Prompt: Initial kernel command string
-#   Location:
-#     -> Kernel options
-# 
-# 
-# 
-CONFIG_CMDLINE=""
diff --git a/redhat/configs/pending-common/generic/CONFIG_PPC_QUEUED_SPINLOCKS b/redhat/configs/pending-common/generic/CONFIG_PPC_QUEUED_SPINLOCKS
deleted file mode 100644
index 90ecdc77e696..000000000000
--- a/redhat/configs/pending-common/generic/CONFIG_PPC_QUEUED_SPINLOCKS
+++ /dev/null
@@ -1,22 +0,0 @@
-# CONFIG_PPC_QUEUED_SPINLOCKS:
-# 
-# Say Y here to use queued spinlocks which give better scalability and
-# fairness on large SMP and NUMA systems without harming single threaded
-# performance.
-# 
-# This option is currently experimental, the code is more complex and
-# less tested so it defaults to "N" for the moment.
-# 
-# If unsure, say "N".
-# 
-# Symbol: PPC_QUEUED_SPINLOCKS [=n]
-# Type  : bool
-# Defined at arch/powerpc/Kconfig:497
-#   Prompt: Queued spinlocks
-#   Depends on: SMP [=y]
-#   Location:
-#     -> Kernel options
-# 
-# 
-# 
-# CONFIG_PPC_QUEUED_SPINLOCKS is not set

[GitLab Bridge on behalf of Waiman Long]

From: Waiman Long on gitlab.com
https://gitlab.com/cki-project/kernel-ark/-/merge_requests/560#note_40614583...

For PPC_QUEUED_SPINLOCKS, I would like to see if enabled in the ARK
kernel.
i.e. PPC_QUEUED_SPINLOCKS=y

That will help performance of large servers with a lot of cpus.

-Longman

[OS-BUILD PATCHv2] New configs in arch/powerpc

[GitLab Bridge on behalf of jeremycline]

From: Fedora Kernel Team

Hi,

As part of the ongoing rebase effort, the following configuration
options need to be reviewed.

As a reminder, the ARK configuration flow involves moving unreviewed
configuration options from the pending directory to the ark directory.
In the diff below, options are removed from the pending directory and
added to the ark hierarchy. The final options that need to be ACKed
are the files that are being added to the ark hierarchy.

If the value for a file that is added should be changed, please reply
with a better option.

CONFIG_CMDLINE:

On some platforms, there is currently no way for the boot loader to
 pass arguments to the kernel. For these platforms, you can supply
 some command-line options at build time by entering them here.  In
 most cases you will need to specify the root device here.

Symbol: CMDLINE [=]
 Type  : string
 Defined at arch/powerpc/Kconfig:882
   Prompt: Initial kernel command string
   Location:
     -> Kernel options

Cc: [e-mail]
---
 redhat/configs/common/generic/CONFIG_CMDLINE  |  1 +
 .../generic/CONFIG_PPC_QUEUED_SPINLOCKS       |  1 +
 .../pending-common/generic/CONFIG_CMDLINE     | 17 --------------
 .../generic/CONFIG_PPC_QUEUED_SPINLOCKS       | 22 -------------------
 4 files changed, 2 insertions(+), 39 deletions(-)
 create mode 100644 redhat/configs/common/generic/CONFIG_CMDLINE
 create mode 100644 redhat/configs/common/generic/CONFIG_PPC_QUEUED_SPINLOCKS
 delete mode 100644 redhat/configs/pending-common/generic/CONFIG_CMDLINE
 delete mode 100644 redhat/configs/pending-common/generic/CONFIG_PPC_QUEUED_SPINLOCKS

diff --git a/redhat/configs/common/generic/CONFIG_CMDLINE b/redhat/configs/common/generic/CONFIG_CMDLINE
new file mode 100644
index 000000000000..f3083e1e5200
--- /dev/null
+++ b/redhat/configs/common/generic/CONFIG_CMDLINE
@@ -0,0 +1 @@
+CONFIG_CMDLINE=""
diff --git a/redhat/configs/common/generic/CONFIG_PPC_QUEUED_SPINLOCKS b/redhat/configs/common/generic/CONFIG_PPC_QUEUED_SPINLOCKS
new file mode 100644
index 000000000000..f1f7e79da5c3
--- /dev/null
+++ b/redhat/configs/common/generic/CONFIG_PPC_QUEUED_SPINLOCKS
@@ -0,0 +1 @@
+# CONFIG_PPC_QUEUED_SPINLOCKS is not set
diff --git a/redhat/configs/pending-common/generic/CONFIG_CMDLINE b/redhat/configs/pending-common/generic/CONFIG_CMDLINE
deleted file mode 100644
index 10611732c5eb..000000000000
--- a/redhat/configs/pending-common/generic/CONFIG_CMDLINE
+++ /dev/null
@@ -1,17 +0,0 @@
-# CONFIG_CMDLINE:
-# 
-# On some platforms, there is currently no way for the boot loader to
-# pass arguments to the kernel. For these platforms, you can supply
-# some command-line options at build time by entering them here.  In
-# most cases you will need to specify the root device here.
-# 
-# Symbol: CMDLINE [=]
-# Type  : string
-# Defined at arch/powerpc/Kconfig:882
-#   Prompt: Initial kernel command string
-#   Location:
-#     -> Kernel options
-# 
-# 
-# 
-CONFIG_CMDLINE=""
diff --git a/redhat/configs/pending-common/generic/CONFIG_PPC_QUEUED_SPINLOCKS b/redhat/configs/pending-common/generic/CONFIG_PPC_QUEUED_SPINLOCKS
deleted file mode 100644
index 90ecdc77e696..000000000000
--- a/redhat/configs/pending-common/generic/CONFIG_PPC_QUEUED_SPINLOCKS
+++ /dev/null
@@ -1,22 +0,0 @@
-# CONFIG_PPC_QUEUED_SPINLOCKS:
-# 
-# Say Y here to use queued spinlocks which give better scalability and
-# fairness on large SMP and NUMA systems without harming single threaded
-# performance.
-# 
-# This option is currently experimental, the code is more complex and
-# less tested so it defaults to "N" for the moment.
-# 
-# If unsure, say "N".
-# 
-# Symbol: PPC_QUEUED_SPINLOCKS [=n]
-# Type  : bool
-# Defined at arch/powerpc/Kconfig:497
-#   Prompt: Queued spinlocks
-#   Depends on: SMP [=y]
-#   Location:
-#     -> Kernel options
-# 
-# 
-# 
-# CONFIG_PPC_QUEUED_SPINLOCKS is not set

[OS-BUILD PATCHv2] New configs in arch/powerpc

From: Justin Forbes on gitlab.com
https://gitlab.com/cki-project/kernel-ark/-/merge_requests/560#note_51732529...

c9f3401313a5089f100d7d1ef4b75cd7b49b2190 changes this a bit:

powerpc: Always enable queued spinlocks for 64s, disable for others

Queued spinlocks have shown to have good performance and fairness
    properties even on smaller (2 socket) POWER systems. This selects
them
    automatically for 64s. For other platforms they are de-selected, the
    standard spinlock is far simpler and smaller code, and single chips
    with a handful of cores is unlikely to show any improvement.

CONFIG_EXPERT still allows this to be changed, e.g., to help debug
    performance or correctness issues.

If you wish to leave CONFIG_PPC_QUEUED_SPINLOCKS off, we will have to
enable CONFIG_EXPERT, and set anything else that it exposes.  I have
changed pending to CONFIG_PPC_QUEUED_SPINLOCKS=y for now.

[OS-BUILD PATCHv2] New configs in arch/powerpc

From: Don Zickus on gitlab.com
https://gitlab.com/cki-project/kernel-ark/-/merge_requests/560#note_51739955...

In the past we have crafted RHEL-only patches that removes the
CONFIG_EXPERT for certain options to allow us to use them.  This may be
an option we use here, unfortunately.

Cheers,
Don

[OS-BUILD PATCHv2] New configs in arch/powerpc

From: Justin Forbes on gitlab.com
https://gitlab.com/cki-project/kernel-ark/-/merge_requests/560#note_51741492...

It may be, but clearly upstream feels that this option is a performance
win, so perhaps it is worth evaluating keeping it on. I have turned it
on for Fedora.

[OS-BUILD PATCHv2] New configs in arch/powerpc

From: Gustavo Luiz Duarte on gitlab.com
https://gitlab.com/cki-project/kernel-ark/-/merge_requests/560#note_51753152...

FWIW, I contacted the powerpc upstream maintainer and we agree that
CONFIG_PPC_QUEUED_SPINLOCKS should be enabled in Fedora and RHEL9. It is
on by default in mainline now.

[OS-BUILD PATCHv2] New configs in arch/powerpc

From: Waiman Long on gitlab.com
https://gitlab.com/cki-project/kernel-ark/-/merge_requests/560#note_51841730...

Using qspinlock is certainly a performance win for large systems with
many cpus. Even on 1-socket system, the performance should be comparable
with the current TAS spinlock. I will not suggest explicitly disabling
it. Switching between TAS spinlock and qspinlock does break kABI (at
least for the paravirtual version). If not, I would have backported it
to RHEL8.

Cheers,
Longman