From nobody Thu Dec 18 08:34:11 2025 Received: from linux.microsoft.com (linux.microsoft.com [13.77.154.182]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 4D269125B9; Thu, 25 Jul 2024 05:26:18 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=13.77.154.182 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1721885179; cv=none; b=hgkoEjmzLUWUZCaJa8B6JlNJcJBX5fsHUixR63yvw/v4HD97TuPTRpSSBz5JBBC4clWsV74kQLQOhYvzxqTqoYcoDsQ5DV343lnNABW+VlsKJi58aFUZ09cdHgdQRdelAxFnI25HfePANCgpkvoZVXJbnd+TQpwJHIAvVkV7OHQ= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1721885179; c=relaxed/simple; bh=tRluP6WyVirJy8G2zBCqGpb2tqnlhAegLSpbjCzVCBM=; h=From:To:Cc:Subject:Date:Message-Id; b=XSjdEYHamHGh2ycZKrQKCcZrqY0BTWpo0zXkap5i7hxbQtvo+IfNAFxOzRwtj+HQBYj0nfrk7ael/ldNJfRNgdtbW0ZHaYDdDntdWrA1h+iixOnbzeaGnRaEiEwG4oOKx/w5yIGFsuv4r88xSX+kYoWryJ8IEr7NdB1+0RAXVho= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.microsoft.com; spf=pass smtp.mailfrom=linux.microsoft.com; dkim=pass (1024-bit key) header.d=linux.microsoft.com header.i=@linux.microsoft.com header.b=aazhQlQn; arc=none smtp.client-ip=13.77.154.182 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.microsoft.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.microsoft.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.microsoft.com header.i=@linux.microsoft.com header.b="aazhQlQn" Received: from linuxonhyperv3.guj3yctzbm1etfxqx2vob5hsef.xx.internal.cloudapp.net (linux.microsoft.com [13.77.154.182]) by linux.microsoft.com (Postfix) with ESMTPSA id BBED020B7165; Wed, 24 Jul 2024 22:26:12 -0700 (PDT) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com BBED020B7165 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1721885172; bh=daSIVeFPy9XrJZuvHVC2wNjvN5BkHjuD/V8ojvrxBP4=; h=From:To:Cc:Subject:Date:From; b=aazhQlQnIEZWV8AX7eGKG1CPAxqxNU2cxe8pZjICNXCQ269UFK/OLdinu/rM8BR46 cAxrwXQwC5mglefOhydfURnV7i8BjIUMzlVX+u8dZsbLujU7Te0M8z05A6U/+Ein2B 1ljukPSHlIR60hvRt7+UQYKoKeJDPY/HN80zNJE4= From: Saurabh Sengar To: kys@microsoft.com, haiyangz@microsoft.com, wei.liu@kernel.org, decui@microsoft.com, linux-hyperv@vger.kernel.org, linux-kernel@vger.kernel.org Cc: ssengar@microsoft.com, srivatsa@csail.mit.edu Subject: [PATCH] Drivers: hv: vmbus: Deferring per cpu tasks Date: Wed, 24 Jul 2024 22:26:04 -0700 Message-Id: <1721885164-6962-1-git-send-email-ssengar@linux.microsoft.com> X-Mailer: git-send-email 1.8.3.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Currently on a very large system with 1780 CPUs, hv_acpi_init takes around 3 seconds to complete for all the CPUs. This is because of sequential synic initialization for each CPU. Defer these tasks so that each CPU executes hv_acpi_init in parallel to take full advantage of multiple CPUs. This solution saves around 2 seconds of boot time on a 1780 CPU system, that around 66% improvement in the existing logic. Signed-off-by: Saurabh Sengar Reviewed-by: Nuno Das Neves --- drivers/hv/vmbus_drv.c | 33 ++++++++++++++++++++++++++++++--- 1 file changed, 30 insertions(+), 3 deletions(-) diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c index c857dc3975be..3395526ad0d0 100644 --- a/drivers/hv/vmbus_drv.c +++ b/drivers/hv/vmbus_drv.c @@ -1306,6 +1306,13 @@ static irqreturn_t vmbus_percpu_isr(int irq, void *d= ev_id) return IRQ_HANDLED; } =20 +static void vmbus_percpu_work(struct work_struct *work) +{ + unsigned int cpu =3D smp_processor_id(); + + hv_synic_init(cpu); +} + /* * vmbus_bus_init -Main vmbus driver initialization routine. * @@ -1316,7 +1323,8 @@ static irqreturn_t vmbus_percpu_isr(int irq, void *de= v_id) */ static int vmbus_bus_init(void) { - int ret; + int ret, cpu; + struct work_struct __percpu *works; =20 ret =3D hv_init(); if (ret !=3D 0) { @@ -1355,12 +1363,31 @@ static int vmbus_bus_init(void) if (ret) goto err_alloc; =20 + works =3D alloc_percpu(struct work_struct); + if (!works) { + ret =3D -ENOMEM; + goto err_alloc; + } + /* * Initialize the per-cpu interrupt state and stimer state. * Then connect to the host. */ - ret =3D cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "hyperv/vmbus:online", - hv_synic_init, hv_synic_cleanup); + cpus_read_lock(); + for_each_online_cpu(cpu) { + struct work_struct *work =3D per_cpu_ptr(works, cpu); + + INIT_WORK(work, vmbus_percpu_work); + schedule_work_on(cpu, work); + } + + for_each_online_cpu(cpu) + flush_work(per_cpu_ptr(works, cpu)); + + ret =3D __cpuhp_setup_state_cpuslocked(CPUHP_AP_ONLINE_DYN, "hyperv/vmbus= :online", false, + hv_synic_init, hv_synic_cleanup, false); + cpus_read_unlock(); + free_percpu(works); if (ret < 0) goto err_alloc; hyperv_cpuhp_online =3D ret; --=20 2.43.0