From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-10.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9C7E1C18E5B for ; Mon, 16 Mar 2020 11:54:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6B0162071C for ; Mon, 16 Mar 2020 11:54:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1584359694; bh=AyyqWFicmezYrufAMr8UkkNZBDHNMHGsGNnQRTSAWFQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=2XZnP/2gatAFwUAllylG4DPr9zzxpUcAexRBGSm5Yg2qNKIDM9qG9lM1NLUAScZ61 +oad0mZNEmlii87/ooM6peoyzaJGL4cpZWRFxAUWo7OyNZD+mERR9aI2apieixwz4l REwtWw0oOtTarqsPzYDRlBd5/ESuTmXSHwKVOxhA= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730947AbgCPLyx (ORCPT ); Mon, 16 Mar 2020 07:54:53 -0400 Received: from mail.kernel.org ([198.145.29.99]:51578 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730907AbgCPLyu (ORCPT ); Mon, 16 Mar 2020 07:54:50 -0400 Received: from disco-boy.misterjones.org (disco-boy.misterjones.org [51.254.78.96]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 9F17320719; Mon, 16 Mar 2020 11:54:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1584359689; bh=AyyqWFicmezYrufAMr8UkkNZBDHNMHGsGNnQRTSAWFQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=HjqEzoW9YkfNMpA+szdgf016wjqszAnHRrJON/B8SeFFRfsmEN4vtOEw80WbVtFxB qKRHSpHwxed61ZNU4D6ecZLyhufDxqDFrVWwN0xzwWdcH/h6Z2Yu9MZoUQ8ncOfYpB GsUhVVRBGPCBBr2/TrPEvC6mgfJUge07mtEQBrlw= Received: from 78.163-31-62.static.virginmediabusiness.co.uk ([62.31.163.78] helo=why.lan) by disco-boy.misterjones.org with esmtpsa (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1jDoKV-00D45x-W3; Mon, 16 Mar 2020 11:54:48 +0000 From: Marc Zyngier To: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org Cc: John Garry , chenxiang , Zhou Wang , Ming Lei , Jason Cooper , Thomas Gleixner Subject: [PATCH v3 2/2] irqchip/gic-v3-its: Balance initial LPI affinity across CPUs Date: Mon, 16 Mar 2020 11:54:33 +0000 Message-Id: <20200316115433.9017-3-maz@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20200316115433.9017-1-maz@kernel.org> References: <20200316115433.9017-1-maz@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-SA-Exim-Connect-IP: 62.31.163.78 X-SA-Exim-Rcpt-To: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, john.garry@huawei.com, chenxiang66@hisilicon.com, wangzhou1@hisilicon.com, ming.lei@redhat.com, jason@lakedaemon.net, tglx@linutronix.de X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org When mapping a LPI, the ITS driver picks the first possible affinity, which is in most cases CPU0, assuming that if that's not suitable, someone will come and set the affinity to something more interesting. It apparently isn't the case, and people complain of poor performance when many interrupts are glued to the same CPU. So let's place the interrupts by finding the "least loaded" CPU (that is, the one that has the fewer LPIs mapped to it). So called 'managed' interrupts are an interesting case where the affinity is actually dictated by the kernel itself, and we should honor this. Reported-by: John Garry Link: https://lore.kernel.org/r/1575642904-58295-1-git-send-email-john.garry@huawei.com Signed-off-by: Marc Zyngier --- drivers/irqchip/irq-gic-v3-its.c | 118 ++++++++++++++++++++++++------- 1 file changed, 92 insertions(+), 26 deletions(-) diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c index 941786e1e8f7..7f1b731c04bb 100644 --- a/drivers/irqchip/irq-gic-v3-its.c +++ b/drivers/irqchip/irq-gic-v3-its.c @@ -1531,31 +1531,107 @@ static void its_dec_lpi_count(struct irq_data *d, int cpu) atomic_dec(&per_cpu_ptr(&cpu_lpi_count, cpu)->unmanaged); } +static unsigned int cpumask_pick_least_loaded(struct irq_data *d, + const struct cpumask *cpu_mask) +{ + unsigned int cpu = nr_cpu_ids, tmp; + int count = S32_MAX; + + for_each_cpu(tmp, cpu_mask) { + int this_count = its_read_lpi_count(d, tmp); + if (this_count < count) { + cpu = tmp; + count = this_count; + } + } + + return cpu; +} + +/* + * As suggested by Thomas Gleixner in: + * https://lore.kernel.org/r/87h80q2aoc.fsf@nanos.tec.linutronix.de + */ +static int its_select_cpu(struct irq_data *d, + const struct cpumask *aff_mask) +{ + struct its_device *its_dev = irq_data_get_irq_chip_data(d); + cpumask_var_t tmpmask; + int cpu, node; + + if (!alloc_cpumask_var(&tmpmask, GFP_KERNEL)) + return -ENOMEM; + + node = its_dev->its->numa_node; + + if (!irqd_affinity_is_managed(d)) { + /* First try the NUMA node */ + if (node != NUMA_NO_NODE) { + /* + * Try the intersection of the affinity mask and the + * node mask (and the online mask, just to be safe). + */ + cpumask_and(tmpmask, cpumask_of_node(node), aff_mask); + cpumask_and(tmpmask, tmpmask, cpu_online_mask); + + /* If that doesn't work, try the nodemask itself */ + if (cpumask_empty(tmpmask)) + cpumask_and(tmpmask, cpumask_of_node(node), cpu_online_mask); + + cpu = cpumask_pick_least_loaded(d, tmpmask); + if (cpu < nr_cpu_ids) + goto out; + + /* If we can't cross sockets, give up */ + if ((its_dev->its->flags & ITS_FLAGS_WORKAROUND_CAVIUM_23144)) + goto out; + + /* If the above failed, expand the search */ + } + + /* Try the intersection of the affinity and online masks */ + cpumask_and(tmpmask, aff_mask, cpu_online_mask); + + /* If that doesn't fly, the online mask is the last resort */ + if (cpumask_empty(tmpmask)) + cpumask_copy(tmpmask, cpu_online_mask); + + cpu = cpumask_pick_least_loaded(d, tmpmask); + } else { + cpumask_and(tmpmask, irq_data_get_affinity_mask(d), cpu_online_mask); + + /* If we cannot cross sockets, limit the search to that node */ + if ((its_dev->its->flags & ITS_FLAGS_WORKAROUND_CAVIUM_23144) && + node != NUMA_NO_NODE) + cpumask_and(tmpmask, tmpmask, cpumask_of_node(node)); + + cpu = cpumask_pick_least_loaded(d, tmpmask); + } +out: + free_cpumask_var(tmpmask); + + pr_debug("IRQ%d -> %*pbl CPU%d\n", d->irq, cpumask_pr_args(aff_mask), cpu); + return cpu; +} + static int its_set_affinity(struct irq_data *d, const struct cpumask *mask_val, bool force) { - unsigned int cpu; - const struct cpumask *cpu_mask = cpu_online_mask; struct its_device *its_dev = irq_data_get_irq_chip_data(d); struct its_collection *target_col; u32 id = its_get_event_id(d); + int cpu; /* A forwarded interrupt should use irq_set_vcpu_affinity */ if (irqd_is_forwarded_to_vcpu(d)) return -EINVAL; - /* lpi cannot be routed to a redistributor that is on a foreign node */ - if (its_dev->its->flags & ITS_FLAGS_WORKAROUND_CAVIUM_23144) { - if (its_dev->its->numa_node >= 0) { - cpu_mask = cpumask_of_node(its_dev->its->numa_node); - if (!cpumask_intersects(mask_val, cpu_mask)) - return -EINVAL; - } - } - - cpu = cpumask_any_and(mask_val, cpu_mask); + if (!force) + cpu = its_select_cpu(d, mask_val); + else + cpu = cpumask_pick_least_loaded(d, mask_val); - if (cpu >= nr_cpu_ids) + if (cpu < 0 || cpu >= nr_cpu_ids) return -EINVAL; /* don't set the affinity when the target cpu is same as current one */ @@ -3455,21 +3531,11 @@ static int its_irq_domain_activate(struct irq_domain *domain, { struct its_device *its_dev = irq_data_get_irq_chip_data(d); u32 event = its_get_event_id(d); - const struct cpumask *cpu_mask = cpu_online_mask; int cpu; - /* get the cpu_mask of local node */ - if (its_dev->its->numa_node >= 0) - cpu_mask = cpumask_of_node(its_dev->its->numa_node); - - /* Bind the LPI to the first possible CPU */ - cpu = cpumask_first_and(cpu_mask, cpu_online_mask); - if (cpu >= nr_cpu_ids) { - if (its_dev->its->flags & ITS_FLAGS_WORKAROUND_CAVIUM_23144) - return -EINVAL; - - cpu = cpumask_first(cpu_online_mask); - } + cpu = its_select_cpu(d, cpu_online_mask); + if (cpu < 0 || cpu >= nr_cpu_ids) + return -EINVAL; its_inc_lpi_count(d, cpu); its_dev->event_map.col_map[event] = cpu; -- 2.20.1