diff options
author | Nick Desaulniers <ndesaulniers@google.com> | 2022-06-28 23:04:07 +0200 |
---|---|---|
committer | Masahiro Yamada <masahiroy@kernel.org> | 2022-07-27 14:17:59 +0200 |
commit | a6036a41bffba3d5007e377483b425d470ad8042 (patch) | |
tree | 5e2922a9b7700c8c702df80b7d6d0272996d6b1c | |
parent | kbuild: remove sed command from cmd_ar_builtin (diff) | |
download | linux-a6036a41bffba3d5007e377483b425d470ad8042.tar.xz linux-a6036a41bffba3d5007e377483b425d470ad8042.zip |
kbuild: drop support for CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE_O3
The difference in most compilers between `-O3` and `-O2` is mostly down
to whether loops with statically determinable trip counts are fully
unrolled vs unrolled to a multiple of SIMD width.
This patch is effectively a revert of
commit 15f5db60a137 ("kbuild,arc: add
CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE_O3 for ARC") without re-adding
ARCH_CFLAGS
Ever since
commit cfdbc2e16e65 ("ARC: Build system: Makefiles, Kconfig, Linker
script")
ARC has been built with -O3, though the reason for doing so was not
specified in inline comments or the commit message. This commit does not
re-add -O3 to arch/arc/Makefile.
Folks looking to experiment with `-O3` (or any compiler flag for that
matter) may pass them along to the command line invocation of make:
$ make KCFLAGS=-O3
Code that looks to re-add an explicit Kconfig option for `-O3` should
provide:
1. A rigorous and reproducible performance profile of a reasonable
userspace workload that demonstrates a hot loop in the kernel that
would benefit from `-O3` over `-O2`.
2. Disassembly of said loop body before and after.
3. Provides stats on terms of increase in file size.
Link: https://lore.kernel.org/linux-kbuild/CA+55aFz2sNBbZyg-_i8_Ldr2e8o9dfvdSfHHuRzVtP2VMAUWPg@mail.gmail.com/
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
-rw-r--r-- | Makefile | 2 | ||||
-rw-r--r-- | arch/arc/configs/axs101_defconfig | 1 | ||||
-rw-r--r-- | arch/arc/configs/axs103_defconfig | 1 | ||||
-rw-r--r-- | arch/arc/configs/axs103_smp_defconfig | 1 | ||||
-rw-r--r-- | arch/arc/configs/haps_hs_defconfig | 1 | ||||
-rw-r--r-- | arch/arc/configs/haps_hs_smp_defconfig | 1 | ||||
-rw-r--r-- | arch/arc/configs/hsdk_defconfig | 1 | ||||
-rw-r--r-- | arch/arc/configs/nsim_700_defconfig | 1 | ||||
-rw-r--r-- | arch/arc/configs/nsimosci_defconfig | 1 | ||||
-rw-r--r-- | arch/arc/configs/nsimosci_hs_defconfig | 1 | ||||
-rw-r--r-- | arch/arc/configs/nsimosci_hs_smp_defconfig | 1 | ||||
-rw-r--r-- | arch/arc/configs/tb10x_defconfig | 1 | ||||
-rw-r--r-- | arch/arc/configs/vdk_hs38_defconfig | 1 | ||||
-rw-r--r-- | arch/arc/configs/vdk_hs38_smp_defconfig | 1 | ||||
-rw-r--r-- | init/Kconfig | 7 |
15 files changed, 0 insertions, 22 deletions
@@ -755,8 +755,6 @@ KBUILD_CFLAGS += $(call cc-disable-warning, address-of-packed-member) ifdef CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE KBUILD_CFLAGS += -O2 -else ifdef CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE_O3 -KBUILD_CFLAGS += -O3 else ifdef CONFIG_CC_OPTIMIZE_FOR_SIZE KBUILD_CFLAGS += -Os endif diff --git a/arch/arc/configs/axs101_defconfig b/arch/arc/configs/axs101_defconfig index 0016149f9583..e31a8ebc3ecc 100644 --- a/arch/arc/configs/axs101_defconfig +++ b/arch/arc/configs/axs101_defconfig @@ -9,7 +9,6 @@ CONFIG_NAMESPACES=y # CONFIG_UTS_NS is not set # CONFIG_PID_NS is not set CONFIG_BLK_DEV_INITRD=y -CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE_O3=y CONFIG_EMBEDDED=y CONFIG_PERF_EVENTS=y # CONFIG_VM_EVENT_COUNTERS is not set diff --git a/arch/arc/configs/axs103_defconfig b/arch/arc/configs/axs103_defconfig index 5b031582a1cf..e0e8567f0d75 100644 --- a/arch/arc/configs/axs103_defconfig +++ b/arch/arc/configs/axs103_defconfig @@ -9,7 +9,6 @@ CONFIG_NAMESPACES=y # CONFIG_UTS_NS is not set # CONFIG_PID_NS is not set CONFIG_BLK_DEV_INITRD=y -CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE_O3=y CONFIG_EMBEDDED=y CONFIG_PERF_EVENTS=y # CONFIG_VM_EVENT_COUNTERS is not set diff --git a/arch/arc/configs/axs103_smp_defconfig b/arch/arc/configs/axs103_smp_defconfig index d4eec39e0112..fcbc952bc75b 100644 --- a/arch/arc/configs/axs103_smp_defconfig +++ b/arch/arc/configs/axs103_smp_defconfig @@ -9,7 +9,6 @@ CONFIG_NAMESPACES=y # CONFIG_UTS_NS is not set # CONFIG_PID_NS is not set CONFIG_BLK_DEV_INITRD=y -CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE_O3=y CONFIG_EMBEDDED=y CONFIG_PERF_EVENTS=y # CONFIG_VM_EVENT_COUNTERS is not set diff --git a/arch/arc/configs/haps_hs_defconfig b/arch/arc/configs/haps_hs_defconfig index 7337cdf4ffdd..d87ad7e88d62 100644 --- a/arch/arc/configs/haps_hs_defconfig +++ b/arch/arc/configs/haps_hs_defconfig @@ -11,7 +11,6 @@ CONFIG_NAMESPACES=y # CONFIG_UTS_NS is not set # CONFIG_PID_NS is not set CONFIG_BLK_DEV_INITRD=y -CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE_O3=y CONFIG_EXPERT=y CONFIG_PERF_EVENTS=y # CONFIG_COMPAT_BRK is not set diff --git a/arch/arc/configs/haps_hs_smp_defconfig b/arch/arc/configs/haps_hs_smp_defconfig index bc927221afc0..8d82cdb7f86a 100644 --- a/arch/arc/configs/haps_hs_smp_defconfig +++ b/arch/arc/configs/haps_hs_smp_defconfig @@ -11,7 +11,6 @@ CONFIG_NAMESPACES=y # CONFIG_UTS_NS is not set # CONFIG_PID_NS is not set CONFIG_BLK_DEV_INITRD=y -CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE_O3=y CONFIG_EMBEDDED=y CONFIG_PERF_EVENTS=y # CONFIG_VM_EVENT_COUNTERS is not set diff --git a/arch/arc/configs/hsdk_defconfig b/arch/arc/configs/hsdk_defconfig index aa000075a575..f856b03e0fb5 100644 --- a/arch/arc/configs/hsdk_defconfig +++ b/arch/arc/configs/hsdk_defconfig @@ -9,7 +9,6 @@ CONFIG_NAMESPACES=y # CONFIG_PID_NS is not set CONFIG_BLK_DEV_INITRD=y CONFIG_BLK_DEV_RAM=y -CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE_O3=y CONFIG_EMBEDDED=y CONFIG_PERF_EVENTS=y # CONFIG_VM_EVENT_COUNTERS is not set diff --git a/arch/arc/configs/nsim_700_defconfig b/arch/arc/configs/nsim_700_defconfig index 326f6cde7826..a1ce12bf5b16 100644 --- a/arch/arc/configs/nsim_700_defconfig +++ b/arch/arc/configs/nsim_700_defconfig @@ -11,7 +11,6 @@ CONFIG_NAMESPACES=y # CONFIG_UTS_NS is not set # CONFIG_PID_NS is not set CONFIG_BLK_DEV_INITRD=y -CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE_O3=y CONFIG_KALLSYMS_ALL=y CONFIG_EMBEDDED=y CONFIG_PERF_EVENTS=y diff --git a/arch/arc/configs/nsimosci_defconfig b/arch/arc/configs/nsimosci_defconfig index bf39a0091679..ca10f4a2c823 100644 --- a/arch/arc/configs/nsimosci_defconfig +++ b/arch/arc/configs/nsimosci_defconfig @@ -10,7 +10,6 @@ CONFIG_NAMESPACES=y # CONFIG_UTS_NS is not set # CONFIG_PID_NS is not set CONFIG_BLK_DEV_INITRD=y -CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE_O3=y CONFIG_KALLSYMS_ALL=y CONFIG_EMBEDDED=y CONFIG_PERF_EVENTS=y diff --git a/arch/arc/configs/nsimosci_hs_defconfig b/arch/arc/configs/nsimosci_hs_defconfig index 7121bd71c543..31b6ec3683c6 100644 --- a/arch/arc/configs/nsimosci_hs_defconfig +++ b/arch/arc/configs/nsimosci_hs_defconfig @@ -10,7 +10,6 @@ CONFIG_NAMESPACES=y # CONFIG_UTS_NS is not set # CONFIG_PID_NS is not set CONFIG_BLK_DEV_INITRD=y -CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE_O3=y CONFIG_KALLSYMS_ALL=y CONFIG_EMBEDDED=y CONFIG_PERF_EVENTS=y diff --git a/arch/arc/configs/nsimosci_hs_smp_defconfig b/arch/arc/configs/nsimosci_hs_smp_defconfig index f9863b294a70..41a0037f48a5 100644 --- a/arch/arc/configs/nsimosci_hs_smp_defconfig +++ b/arch/arc/configs/nsimosci_hs_smp_defconfig @@ -8,7 +8,6 @@ CONFIG_IKCONFIG_PROC=y # CONFIG_UTS_NS is not set # CONFIG_PID_NS is not set CONFIG_BLK_DEV_INITRD=y -CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE_O3=y CONFIG_PERF_EVENTS=y # CONFIG_COMPAT_BRK is not set CONFIG_KPROBES=y diff --git a/arch/arc/configs/tb10x_defconfig b/arch/arc/configs/tb10x_defconfig index a12656ec0072..d93b65008d4a 100644 --- a/arch/arc/configs/tb10x_defconfig +++ b/arch/arc/configs/tb10x_defconfig @@ -14,7 +14,6 @@ CONFIG_INITRAMFS_SOURCE="../tb10x-rootfs.cpio" CONFIG_INITRAMFS_ROOT_UID=2100 CONFIG_INITRAMFS_ROOT_GID=501 # CONFIG_RD_GZIP is not set -CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE_O3=y CONFIG_KALLSYMS_ALL=y # CONFIG_AIO is not set CONFIG_EMBEDDED=y diff --git a/arch/arc/configs/vdk_hs38_defconfig b/arch/arc/configs/vdk_hs38_defconfig index d7c858df520c..0c3b21416819 100644 --- a/arch/arc/configs/vdk_hs38_defconfig +++ b/arch/arc/configs/vdk_hs38_defconfig @@ -4,7 +4,6 @@ CONFIG_HIGH_RES_TIMERS=y CONFIG_IKCONFIG=y CONFIG_IKCONFIG_PROC=y CONFIG_BLK_DEV_INITRD=y -CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE_O3=y CONFIG_EMBEDDED=y CONFIG_PERF_EVENTS=y # CONFIG_VM_EVENT_COUNTERS is not set diff --git a/arch/arc/configs/vdk_hs38_smp_defconfig b/arch/arc/configs/vdk_hs38_smp_defconfig index 015c1d43889e..f9ad9d3ee702 100644 --- a/arch/arc/configs/vdk_hs38_smp_defconfig +++ b/arch/arc/configs/vdk_hs38_smp_defconfig @@ -4,7 +4,6 @@ CONFIG_HIGH_RES_TIMERS=y CONFIG_IKCONFIG=y CONFIG_IKCONFIG_PROC=y CONFIG_BLK_DEV_INITRD=y -CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE_O3=y CONFIG_EMBEDDED=y CONFIG_PERF_EVENTS=y # CONFIG_VM_EVENT_COUNTERS is not set diff --git a/init/Kconfig b/init/Kconfig index c7900e8975f1..1b4d8acc3def 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -1401,13 +1401,6 @@ config CC_OPTIMIZE_FOR_PERFORMANCE with the "-O2" compiler flag for best performance and most helpful compile-time warnings. -config CC_OPTIMIZE_FOR_PERFORMANCE_O3 - bool "Optimize more for performance (-O3)" - depends on ARC - help - Choosing this option will pass "-O3" to your compiler to optimize - the kernel yet more for performance. - config CC_OPTIMIZE_FOR_SIZE bool "Optimize for size (-Os)" help |