From nobody Wed Feb 11 05:07:47 2026 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 B2440C77B7C for ; Wed, 10 May 2023 16:35:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235786AbjEJQf1 (ORCPT ); Wed, 10 May 2023 12:35:27 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56712 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235757AbjEJQfX (ORCPT ); Wed, 10 May 2023 12:35:23 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 516787D8B; Wed, 10 May 2023 09:35:16 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id D803F63F22; Wed, 10 May 2023 16:35:15 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4BEBAC4339C; Wed, 10 May 2023 16:35:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1683736515; bh=D/zx5C3wzjM0zZXbvIgMONVy5BqICz3TUA896+jQLlk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=pM5PoYrty7yCH0RwPEETSGMTPtIBfqrDnxC1Of4QRrUvRYpcqhfo6CnKstuBdrJ1p Y8cTCUfcyPT9HCkODQhlW0ldspb1r8HMngbvPk58T/mxUVoWPYO0S8YT67WaBZmkkS 0guf3w7XP62n7Ufw6skcC1kTsgNS41PBKc3ftTIiOzKTnQIUvBMw98EWCV5UsjLA28 6w71JHcobAAmgW+ISjtdcEJaao3XBzY1Aov9TpeRhc+o6IRxbfwVCAXdnvBBH/xOYT JabESi0GONWMCoSl4Pw7TmgOCBO1uEBG3nscObwQzvG6izQ9zkRZEu5L++sWiusIiK gcuU64Yx8J6dw== From: Jisheng Zhang To: Sebastian Andrzej Siewior , Thomas Gleixner , Schaffner Tobias , Paul Walmsley , Palmer Dabbelt , Albert Ou , Arnd Bergmann Cc: linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org Subject: [PATCH RT 1/3] asm-generic/preempt: also check preempt_lazy_count for should_resched() etc. Date: Thu, 11 May 2023 00:24:04 +0800 Message-Id: <20230510162406.1955-2-jszhang@kernel.org> X-Mailer: git-send-email 2.40.0 In-Reply-To: <20230510162406.1955-1-jszhang@kernel.org> References: <20230510162406.1955-1-jszhang@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" lazy preempt count is great mechanism to help ordinary SCHED_OTHER tasks' throughput Under PREEMPT_RT. But current implementation relies on each arch-specific code to check the preempt_lazy_count in should_resched() and __preempt_count_dec_and_test(), if the arch, e.g riscv use the asm-generic preempt implementation, it losts the great lazy preempt mechanism. Signed-off-by: Jisheng Zhang --- include/asm-generic/preempt.h | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/include/asm-generic/preempt.h b/include/asm-generic/preempt.h index b4d43a4af5f7..b583e7c38ccf 100644 --- a/include/asm-generic/preempt.h +++ b/include/asm-generic/preempt.h @@ -59,6 +59,11 @@ static __always_inline void __preempt_count_sub(int val) *preempt_count_ptr() -=3D val; } =20 +#ifdef CONFIG_PREEMPT_LAZY +#define preempt_lazy_count() (current_thread_info()->preempt_lazy_count) +#else +#define preempt_lazy_count() (0) +#endif static __always_inline bool __preempt_count_dec_and_test(void) { /* @@ -66,7 +71,7 @@ static __always_inline bool __preempt_count_dec_and_test(= void) * operations; we cannot use PREEMPT_NEED_RESCHED because it might get * lost. */ - return !--*preempt_count_ptr() && tif_need_resched(); + return !--*preempt_count_ptr() && !preempt_lazy_count() && tif_need_resch= ed(); } =20 /* @@ -75,6 +80,7 @@ static __always_inline bool __preempt_count_dec_and_test(= void) static __always_inline bool should_resched(int preempt_offset) { return unlikely(preempt_count() =3D=3D preempt_offset && + !preempt_lazy_count() && tif_need_resched()); } =20 --=20 2.40.1 From nobody Wed Feb 11 05:07:47 2026 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 91C5DC7EE22 for ; Wed, 10 May 2023 16:35:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235893AbjEJQfb (ORCPT ); Wed, 10 May 2023 12:35:31 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56750 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235791AbjEJQfY (ORCPT ); Wed, 10 May 2023 12:35:24 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1A7E87EF5; Wed, 10 May 2023 09:35:19 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id A084964A05; Wed, 10 May 2023 16:35:18 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id B40CFC433D2; Wed, 10 May 2023 16:35:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1683736518; bh=rdwY2xPsMRjdNsYlKkpqfjxeCKdDEMu/9hjRoCJFxdM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=jt9AEIH+Dyddi6upgEhmzbo0fW2sCgcsIL5E6plZniKbKA3pV+N8YJjYfNbgcfwfI pU1FPgMKrfhVZfDOq4TC9Q91xNagOIHErXf/eUG2TF2iqO+4KO9SGWCkhZJHqVxbmn 1PkCFUgUyAHLUXY2Vvb2OLi7TpcCFCcr0JhL9dkLRaUOnRSpf3OZFHe6ZWj5H0OXKf R4VZ6XsZHX6vPyZ6rpZNo10EDdTAMHqE807ESgfFQIjq6IhlEoSjMFntg6+cYWX0Ws CBxsWm9Qc4APR2g/yPNAeym0GCuDnX9NzSsw6YgWtAu37F4NQw7Wc7K9SB/MAaSPfy 6xuhdKDTG25lg== From: Jisheng Zhang To: Sebastian Andrzej Siewior , Thomas Gleixner , Schaffner Tobias , Paul Walmsley , Palmer Dabbelt , Albert Ou , Arnd Bergmann Cc: linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org Subject: [PATCH RT 2/3] riscv: add lazy preempt support Date: Thu, 11 May 2023 00:24:05 +0800 Message-Id: <20230510162406.1955-3-jszhang@kernel.org> X-Mailer: git-send-email 2.40.0 In-Reply-To: <20230510162406.1955-1-jszhang@kernel.org> References: <20230510162406.1955-1-jszhang@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" Implement the lazy preempt for riscv. Signed-off-by: Jisheng Zhang --- arch/riscv/Kconfig | 1 + arch/riscv/include/asm/thread_info.h | 5 ++++- arch/riscv/kernel/asm-offsets.c | 1 + 3 files changed, 6 insertions(+), 1 deletion(-) diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig index 348c0fa1fc8c..89e9d9fb35c4 100644 --- a/arch/riscv/Kconfig +++ b/arch/riscv/Kconfig @@ -118,6 +118,7 @@ config RISCV select HAVE_PERF_REGS select HAVE_PERF_USER_STACK_DUMP select HAVE_POSIX_CPU_TIMERS_TASK_WORK + select HAVE_PREEMPT_LAZY select HAVE_REGS_AND_STACK_ACCESS_API select HAVE_RSEQ select HAVE_STACKPROTECTOR diff --git a/arch/riscv/include/asm/thread_info.h b/arch/riscv/include/asm/= thread_info.h index e0d202134b44..c5e9223e9b91 100644 --- a/arch/riscv/include/asm/thread_info.h +++ b/arch/riscv/include/asm/thread_info.h @@ -59,6 +59,7 @@ extern unsigned long spin_shadow_stack; struct thread_info { unsigned long flags; /* low level flags */ int preempt_count; /* 0=3D>preemptible, <0=3D>BUG */ + int preempt_lazy_count; /* 0=3D>preemptible, <0=3D>BUG */ /* * These stack pointers are overwritten on every system call or * exception. SP is also saved to the stack it can be recovered when @@ -90,6 +91,7 @@ struct thread_info { * - pending work-to-be-done flags are in lowest half-word * - other flags in upper half-word(s) */ +#define TIF_NEED_RESCHED_LAZY 0 /* lazy rescheduling */ #define TIF_NOTIFY_RESUME 1 /* callback before returning to user */ #define TIF_SIGPENDING 2 /* signal pending */ #define TIF_NEED_RESCHED 3 /* rescheduling necessary */ @@ -104,9 +106,10 @@ struct thread_info { #define _TIF_NEED_RESCHED (1 << TIF_NEED_RESCHED) #define _TIF_NOTIFY_SIGNAL (1 << TIF_NOTIFY_SIGNAL) #define _TIF_UPROBE (1 << TIF_UPROBE) +#define _TIF_NEED_RESCHED_LAZY (1 << TIF_NEED_RESCHED_LAZY) =20 #define _TIF_WORK_MASK \ (_TIF_NOTIFY_RESUME | _TIF_SIGPENDING | _TIF_NEED_RESCHED | \ - _TIF_NOTIFY_SIGNAL | _TIF_UPROBE) + _TIF_NEED_RESCHED_LAZY | _TIF_NOTIFY_SIGNAL | _TIF_UPROBE) =20 #endif /* _ASM_RISCV_THREAD_INFO_H */ diff --git a/arch/riscv/kernel/asm-offsets.c b/arch/riscv/kernel/asm-offset= s.c index d6a75aac1d27..1f8cccacb44e 100644 --- a/arch/riscv/kernel/asm-offsets.c +++ b/arch/riscv/kernel/asm-offsets.c @@ -36,6 +36,7 @@ void asm_offsets(void) OFFSET(TASK_THREAD_S11, task_struct, thread.s[11]); OFFSET(TASK_TI_FLAGS, task_struct, thread_info.flags); OFFSET(TASK_TI_PREEMPT_COUNT, task_struct, thread_info.preempt_count); + OFFSET(TASK_TI_PREEMPT_LAZY_COUNT, task_struct, thread_info.preempt_lazy_= count); OFFSET(TASK_TI_KERNEL_SP, task_struct, thread_info.kernel_sp); OFFSET(TASK_TI_USER_SP, task_struct, thread_info.user_sp); =20 --=20 2.40.1 From nobody Wed Feb 11 05:07:47 2026 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 A8FDFC7EE22 for ; Wed, 10 May 2023 16:35:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229546AbjEJQfm (ORCPT ); Wed, 10 May 2023 12:35:42 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56722 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235814AbjEJQf1 (ORCPT ); Wed, 10 May 2023 12:35:27 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4370183FF; Wed, 10 May 2023 09:35:22 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id C27E4649EF; Wed, 10 May 2023 16:35:21 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id D2B1EC433D2; Wed, 10 May 2023 16:35:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1683736521; bh=g7XPNarzH/wqmr6jhG8yJoDzEIyJ6X2782gc+T1vwWY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=nCemHidxkEx6i5wrALhCiB1N0fHoOy8JS21FwUzqiktdz70tFZZ/3G4V+LmeDhyCg 3BbgC3OUBY8ApUQWdlTKT1qZuq9oCWDpBcyFXMag77sWFKMbhqUXntGuT5PkcCr3h1 vpOVnlTDW7Y77cVA01MxS6o0pIy3LvCaboxMsWdGfAYKtLHU8FbA6J/3BUOf5H53rb 1xYq93qM1j+0U23ySNHGAVLcuIJYAnmDxXunzoYjzXBjktG39OMo5LR2L8nj4q30cC aWEQ4yoi9B60GvVyy1vBbz0gA3ly8xvvW89KqttSsxAFcq2rw9QMj7FB3fZGKi0s3o 2emM8Elpu7nFw== From: Jisheng Zhang To: Sebastian Andrzej Siewior , Thomas Gleixner , Schaffner Tobias , Paul Walmsley , Palmer Dabbelt , Albert Ou , Arnd Bergmann Cc: linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org Subject: [PATCH RT 3/3] riscv: Allow to enable RT Date: Thu, 11 May 2023 00:24:06 +0800 Message-Id: <20230510162406.1955-4-jszhang@kernel.org> X-Mailer: git-send-email 2.40.0 In-Reply-To: <20230510162406.1955-1-jszhang@kernel.org> References: <20230510162406.1955-1-jszhang@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" Now, it's ready to enable RT on riscv. Signed-off-by: Jisheng Zhang --- arch/riscv/Kconfig | 1 + 1 file changed, 1 insertion(+) diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig index 89e9d9fb35c4..622561d1e388 100644 --- a/arch/riscv/Kconfig +++ b/arch/riscv/Kconfig @@ -42,6 +42,7 @@ config RISCV select ARCH_SUPPORTS_DEBUG_PAGEALLOC if MMU select ARCH_SUPPORTS_HUGETLBFS if MMU select ARCH_SUPPORTS_PAGE_TABLE_CHECK if MMU + select ARCH_SUPPORTS_RT select ARCH_USE_MEMTEST select ARCH_USE_QUEUED_RWLOCKS select ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT if MMU --=20 2.40.1