From patchwork Tue Jun 28 21:04:07 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Nick Desaulniers X-Patchwork-Id: 12898966 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9FC55C433EF for ; Tue, 28 Jun 2022 21:06:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231239AbiF1VG3 (ORCPT ); Tue, 28 Jun 2022 17:06:29 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51752 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229795AbiF1VG0 (ORCPT ); Tue, 28 Jun 2022 17:06:26 -0400 Received: from mail-yw1-x1149.google.com (mail-yw1-x1149.google.com [IPv6:2607:f8b0:4864:20::1149]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 46CC7387A1 for ; Tue, 28 Jun 2022 14:06:24 -0700 (PDT) Received: by mail-yw1-x1149.google.com with SMTP id 00721157ae682-3178a95ec78so113443797b3.4 for ; Tue, 28 Jun 2022 14:06:24 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=NBjk3KmSTe6O3r+cvxYAfwMjmFb8XoFUly9qB4s0+Dc=; b=APNpMrpOxLHssUGRCp2dDrS3U6YDR8iMB9nY17tSekazF526G5tnofYcL+GneEuIZq hwfpA5ih5ST2vJUY9ymc30ltjAQjNu9EcZrTXbBErDPAYmqsjCf4FF92zmM57HL6jXsv LHZ2cQ9iGYKfcGfulX5G5FbKv/A86hgHPWTUt91XKAkWDwQtSelnXWA7E961ENKU0wEx HDJqKslHHoT+0dvcREMQQkYnXgN73t/2I+gGC5DCxjw+U19FzS8RsJIOzWKprgGyO0PG yt45zBIWo6DdlPfd6gdbfXGGSKc7Js8tqVdY6qDrumSz9qP5hG8AuDxVr1zlYoK3A6q+ V60Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=NBjk3KmSTe6O3r+cvxYAfwMjmFb8XoFUly9qB4s0+Dc=; b=gSQcI7q+MNsL9KyYcw4pwvw5taKW3933yFPNTIGCb2SYhRRMqBlz4uqsp0ycdonIO4 raMu/CcK+OxavYz82A0e2aT2yVEInnaxq+GwoB4uneYPQoCZ3k0r+nASSo1MewRBc9yP 4rQ9JiuoKARgq1fE290Kn/mVPQ2JLthqMwERSXnzfuMHelKGq5lCVEFrwqkrvjKb/8ga MCk2C3Ajzh7HBNNw9PF8XtTHJvIPli/aUGYPR6hnf6l+QiNMXeV+RxNbT5OAYWhq+6Hj u1TwxTQaOZJInqcteeVMfCpKW0DK2Xgr0upWCl1+3ZHCO1pdCG1/xMBipr0fzmP2GMtL UG0Q== X-Gm-Message-State: AJIora9ww5apOvYBkAj0Fk4CWabGoctsU2uF8OzLvWeF8K4NrGpLcL6Q /lbKbf310MZeFwo/SegdmHlm6oyxoCZT1tIP+yI= X-Google-Smtp-Source: AGRyM1uqbxh15X0ffrMA2K/9ugnCtBuuiODCCvECKPIeqo/pFve31rlV2dvAY//fOQBVv4rrTPbVOCg7ZxjYvEYYrYU= X-Received: from ndesaulniers1.mtv.corp.google.com ([2620:15c:211:202:fc06:3025:c99d:2af7]) (user=ndesaulniers job=sendgmr) by 2002:a25:2185:0:b0:66c:97fb:f6ba with SMTP id h127-20020a252185000000b0066c97fbf6bamr18361471ybh.169.1656450383533; Tue, 28 Jun 2022 14:06:23 -0700 (PDT) Date: Tue, 28 Jun 2022 14:04:07 -0700 In-Reply-To: Message-Id: <20220628210407.3343118-1-ndesaulniers@google.com> Mime-Version: 1.0 References: X-Developer-Key: i=ndesaulniers@google.com; a=ed25519; pk=lvO/pmg+aaCb6dPhyGC1GyOCvPueDrrc8Zeso5CaGKE= X-Developer-Signature: v=1; a=ed25519-sha256; t=1656450247; l=9154; s=20211004; h=from:subject; bh=gvpD1o/b8JZSfOr8fCp8TXjM9bVhNEAdI7IvLmzBEEE=; b=nVhj4qFBlP9ZwYTN7PMDRYc5i+NSY2lfu1PyHgoG7UiKXpO4/BxXiJmVb9CLvzUlW9Ck7UIlIhpn CPuZETO6BScAKn5vPYakOUaU35pM/Wk9wOP/6OzF2BDoriqIdGNb X-Mailer: git-send-email 2.37.0.rc0.161.g10f37bed90-goog Subject: [PATCH] kbuild: drop support for CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE_O3 From: Nick Desaulniers To: Masahiro Yamada , Linus Torvalds Cc: arnd@arndb.de, bigeasy@linutronix.de, chris@chrisdown.name, dmitry.torokhov@gmail.com, gustavoars@kernel.org, john.ogness@linutronix.de, linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org, mikoxyzzz@gmail.com, nathan@kernel.org, ndesaulniers@google.com, oleksandr@redhat.com, quic_eberman@quicinc.com, seanjc@google.com, tglx@linutronix.de, vbabka@suse.cz, x86@kernel.org, linux-snps-arc@lists.infradead.org, Vineet Gupta Precedence: bulk List-ID: X-Mailing-List: linux-kbuild@vger.kernel.org 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 --- Makefile | 2 -- arch/arc/configs/axs101_defconfig | 1 - arch/arc/configs/axs103_defconfig | 1 - arch/arc/configs/axs103_smp_defconfig | 1 - arch/arc/configs/haps_hs_defconfig | 1 - arch/arc/configs/haps_hs_smp_defconfig | 1 - arch/arc/configs/hsdk_defconfig | 1 - arch/arc/configs/nsim_700_defconfig | 1 - arch/arc/configs/nsimosci_defconfig | 1 - arch/arc/configs/nsimosci_hs_defconfig | 1 - arch/arc/configs/nsimosci_hs_smp_defconfig | 1 - arch/arc/configs/tb10x_defconfig | 1 - arch/arc/configs/vdk_hs38_defconfig | 1 - arch/arc/configs/vdk_hs38_smp_defconfig | 1 - init/Kconfig | 7 ------- 15 files changed, 22 deletions(-) diff --git a/Makefile b/Makefile index 8973b285ce6c..b69f6cd7f2e2 100644 --- a/Makefile +++ b/Makefile @@ -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