mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git
synced 2025-01-17 22:05:08 +00:00
a6036a41bf
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>
107 lines
2.7 KiB
Plaintext
107 lines
2.7 KiB
Plaintext
CONFIG_SYSVIPC=y
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CONFIG_POSIX_MQUEUE=y
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# CONFIG_CROSS_MEMORY_ATTACH is not set
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CONFIG_NO_HZ_IDLE=y
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CONFIG_HIGH_RES_TIMERS=y
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CONFIG_IKCONFIG=y
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CONFIG_IKCONFIG_PROC=y
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CONFIG_NAMESPACES=y
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# CONFIG_UTS_NS is not set
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# CONFIG_PID_NS is not set
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CONFIG_BLK_DEV_INITRD=y
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CONFIG_EMBEDDED=y
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CONFIG_PERF_EVENTS=y
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# CONFIG_VM_EVENT_COUNTERS is not set
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# CONFIG_SLUB_DEBUG is not set
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# CONFIG_COMPAT_BRK is not set
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CONFIG_MODULES=y
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CONFIG_MODULE_FORCE_LOAD=y
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CONFIG_MODULE_UNLOAD=y
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CONFIG_MODULE_FORCE_UNLOAD=y
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CONFIG_PARTITION_ADVANCED=y
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CONFIG_ARC_PLAT_AXS10X=y
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CONFIG_AXS103=y
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CONFIG_ISA_ARCV2=y
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CONFIG_ARC_BUILTIN_DTB_NAME="axs103"
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CONFIG_PREEMPT=y
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# CONFIG_COMPACTION is not set
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CONFIG_NET=y
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CONFIG_PACKET=y
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CONFIG_UNIX=y
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CONFIG_NET_KEY=y
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CONFIG_INET=y
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CONFIG_IP_PNP=y
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CONFIG_IP_PNP_DHCP=y
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CONFIG_IP_PNP_BOOTP=y
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CONFIG_IP_PNP_RARP=y
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# CONFIG_INET_XFRM_MODE_TRANSPORT is not set
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# CONFIG_INET_XFRM_MODE_TUNNEL is not set
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# CONFIG_INET_XFRM_MODE_BEET is not set
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# CONFIG_IPV6 is not set
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CONFIG_DEVTMPFS=y
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# CONFIG_STANDALONE is not set
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# CONFIG_PREVENT_FIRMWARE_BUILD is not set
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CONFIG_BLK_DEV_LOOP=y
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CONFIG_SCSI=y
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CONFIG_BLK_DEV_SD=y
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CONFIG_NETDEVICES=y
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# CONFIG_NET_VENDOR_ARC is not set
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# CONFIG_NET_VENDOR_BROADCOM is not set
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# CONFIG_NET_VENDOR_INTEL is not set
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# CONFIG_NET_VENDOR_MARVELL is not set
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# CONFIG_NET_VENDOR_MICREL is not set
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# CONFIG_NET_VENDOR_NATSEMI is not set
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# CONFIG_NET_VENDOR_SEEQ is not set
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CONFIG_STMMAC_ETH=y
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# CONFIG_NET_VENDOR_VIA is not set
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# CONFIG_NET_VENDOR_WIZNET is not set
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CONFIG_NATIONAL_PHY=y
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# CONFIG_USB_NET_DRIVERS is not set
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CONFIG_INPUT_EVDEV=y
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CONFIG_MOUSE_PS2_TOUCHKIT=y
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CONFIG_MOUSE_SERIAL=y
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CONFIG_MOUSE_SYNAPTICS_USB=y
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# CONFIG_LEGACY_PTYS is not set
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CONFIG_SERIAL_8250=y
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CONFIG_SERIAL_8250_CONSOLE=y
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CONFIG_SERIAL_8250_DW=y
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CONFIG_SERIAL_OF_PLATFORM=y
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# CONFIG_HW_RANDOM is not set
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CONFIG_I2C=y
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CONFIG_I2C_CHARDEV=y
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CONFIG_I2C_DESIGNWARE_PLATFORM=y
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# CONFIG_HWMON is not set
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CONFIG_FB=y
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CONFIG_FRAMEBUFFER_CONSOLE=y
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CONFIG_FRAMEBUFFER_CONSOLE_DETECT_PRIMARY=y
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CONFIG_LOGO=y
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# CONFIG_LOGO_LINUX_MONO is not set
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# CONFIG_LOGO_LINUX_VGA16 is not set
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# CONFIG_LOGO_LINUX_CLUT224 is not set
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CONFIG_USB_EHCI_HCD=y
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CONFIG_USB_EHCI_HCD_PLATFORM=y
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CONFIG_USB_OHCI_HCD=y
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CONFIG_USB_OHCI_HCD_PLATFORM=y
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CONFIG_USB_STORAGE=y
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CONFIG_MMC=y
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CONFIG_MMC_SDHCI=y
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CONFIG_MMC_SDHCI_PLTFM=y
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CONFIG_MMC_DW=y
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# CONFIG_IOMMU_SUPPORT is not set
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CONFIG_EXT3_FS=y
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CONFIG_MSDOS_FS=y
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CONFIG_VFAT_FS=y
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CONFIG_NTFS_FS=y
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CONFIG_TMPFS=y
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CONFIG_NFS_FS=y
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CONFIG_NFS_V3_ACL=y
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CONFIG_NLS_CODEPAGE_437=y
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CONFIG_NLS_ISO8859_1=y
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# CONFIG_ENABLE_MUST_CHECK is not set
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CONFIG_STRIP_ASM_SYMS=y
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CONFIG_SOFTLOCKUP_DETECTOR=y
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CONFIG_DEFAULT_HUNG_TASK_TIMEOUT=10
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# CONFIG_SCHED_DEBUG is not set
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# CONFIG_DEBUG_PREEMPT is not set
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# CONFIG_FTRACE is not set
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