From nobody Wed Dec 17 12:14:20 2025 Received: from mail.loongson.cn (mail.loongson.cn [114.242.206.163]) by smtp.subspace.kernel.org (Postfix) with ESMTP id CB6A72FB2 for ; Sun, 17 Nov 2024 05:40:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=114.242.206.163 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1731822041; cv=none; b=besuT1lE85syfA6NuRm95875qtnlVKxqSkmT2rBNtKpugols6UTmmvXRUg3NsfJNXsDnOnf0d4sIfHnCD8Vge3dd9J/u7cVxI5wCDQwSnjsGDGP5MBknIvvZLflrCy4FFmK7UowP9wZPrX+LCana9jA+Lw49M0xdl6W0gKTUCnM= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1731822041; c=relaxed/simple; bh=zhBhIEbH1gp3YvyAIPkxgVzsMDJ8x+9DQe3qhi5ssK0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=GtD6T86RNevrtkqshrk39ufnLOndjBxa+uyoZwjwwESxCUxzNAEmSfar5EKSclkaLfQGnOmBrQSmclkoiIj4UnMKNg7aYN6UWN/9CQrbszK3SpTkuqvLswJe81LcQiL6M9QxA+asK5u9JnSxAFxRY4y8g337sdpQWpA6jzP4lbs= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=loongson.cn; spf=pass smtp.mailfrom=loongson.cn; arc=none smtp.client-ip=114.242.206.163 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=loongson.cn Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=loongson.cn Received: from loongson.cn (unknown [223.64.68.202]) by gateway (Coremail) with SMTP id _____8CxC+LVgTlnGQxAAA--.60511S3; Sun, 17 Nov 2024 13:40:37 +0800 (CST) Received: from localhost.localdomain (unknown [223.64.68.202]) by front1 (Coremail) with SMTP id qMiowMBxO+DDgTlnJ4NZAA--.10317S2; Sun, 17 Nov 2024 13:40:36 +0800 (CST) From: Huacai Chen To: Huacai Chen , Sebastian Andrzej Siewior Cc: loongarch@lists.linux.dev, Clark Williams , Steven Rostedt , linux-rt-devel@lists.linux.dev, Xuerui Wang , Jiaxun Yang , linux-kernel@vger.kernel.org, loongson-kernel@lists.loongnix.cn, Huacai Chen Subject: [PATCH V2 1/4] LoongArch: Reduce min_delta for the arch clockevent device Date: Sun, 17 Nov 2024 13:40:14 +0800 Message-ID: <20241117054017.3938700-1-chenhuacai@loongson.cn> X-Mailer: git-send-email 2.43.5 In-Reply-To: <20241117053740.3938646-1-chenhuacai@loongson.cn> References: <20241117053740.3938646-1-chenhuacai@loongson.cn> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-CM-TRANSID: qMiowMBxO+DDgTlnJ4NZAA--.10317S2 X-CM-SenderInfo: hfkh0x5xdftxo6or00hjvr0hdfq/ X-Coremail-Antispam: 1Uk129KBj9xXoWrZFyxuF43urW7ArWfXF13Awc_yoWkJrc_ur 17Gw1DWr9aqFZIy3ZFgw4rWw1UKw48tFya93ZrWF43Jw15Jr98GFWDXanxArn0qFWYyrs8 Xr4jqr9akr13KosvyTuYvTs0mTUanT9S1TB71UUUUjDqnTZGkaVYY2UrUUUUj1kv1TuYvT s0mT0YCTnIWjqI5I8CrVACY4xI64kE6c02F40Ex7xfYxn0WfASr-VFAUDa7-sFnT9fnUUI cSsGvfJTRUUUbfkYFVCjjxCrM7AC8VAFwI0_Jr0_Gr1l1xkIjI8I6I8E6xAIw20EY4v20x vaj40_Wr0E3s1l1IIY67AEw4v_JrI_Jryl8cAvFVAK0II2c7xJM28CjxkF64kEwVA0rcxS w2x7M28EF7xvwVC0I7IYx2IY67AKxVW8JVW5JwA2z4x0Y4vE2Ix0cI8IcVCY1x0267AKxV W8JVWxJwA2z4x0Y4vEx4A2jsIE14v26r4j6F4UM28EF7xvwVC2z280aVCY1x0267AKxVW8 JVW8Jr1ln4kS14v26r126r1DM2AIxVAIcxkEcVAq07x20xvEncxIr21l57IF6xkI12xvs2 x26I8E6xACxx1l5I8CrVACY4xI64kE6c02F40Ex7xfMcIj6xIIjxv20xvE14v26r1q6rW5 McIj6I8E87Iv67AKxVW8JVWxJwAm72CE4IkC6x0Yz7v_Jr0_Gr1lF7xvr2IYc2Ij64vIr4 1lc7CjxVAaw2AFwI0_JF0_Jw1l42xK82IYc2Ij64vIr41l4I8I3I0E4IkC6x0Yz7v_Jr0_ Gr1l4IxYO2xFxVAFwI0_JF0_Jw1lx2IqxVAqx4xG67AKxVWUJVWUGwC20s026x8GjcxK67 AKxVWUGVWUWwC2zVAF1VAY17CE14v26r1q6r43MIIYrxkI7VAKI48JMIIF0xvE2Ix0cI8I cVAFwI0_Gr0_Xr1lIxAIcVC0I7IYx2IY6xkF7I0E14v26r4j6F4UMIIF0xvE42xK8VAvwI 8IcIk0rVWUJVWUCwCI42IY6I8E87Iv67AKxVW8JVWxJwCI42IY6I8E87Iv6xkF7I0E14v2 6r4j6r4UJbIYCTnIWIevJa73UjIFyTuYvjxU4BHqDUUUU Content-Type: text/plain; charset="utf-8" Now the min_delta is 0x600 (1536) for LoongArch's constant clockevent device. For a 100MHz hardware timer this means ~15us. This is a little big, especially for PREEMPT_RT enabled kernels. So reduce it to 100 for PREEMPT_RT kernel, and 1000 for others (we don't want too small values to affect performance). Signed-off-by: Huacai Chen --- arch/loongarch/kernel/time.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/arch/loongarch/kernel/time.c b/arch/loongarch/kernel/time.c index 46d7d40c87e3..a07d7eff4dc5 100644 --- a/arch/loongarch/kernel/time.c +++ b/arch/loongarch/kernel/time.c @@ -127,7 +127,11 @@ void sync_counter(void) int constant_clockevent_init(void) { unsigned int cpu =3D smp_processor_id(); - unsigned long min_delta =3D 0x600; +#ifdef CONFIG_PREEMPT_RT + unsigned long min_delta =3D 100; +#else + unsigned long min_delta =3D 1000; +#endif unsigned long max_delta =3D (1UL << 48) - 1; struct clock_event_device *cd; static int irq =3D 0, timer_irq_installed =3D 0; --=20 2.43.5