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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2489BC433F5 for ; Fri, 1 Oct 2021 09:33:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id ECB9561440 for ; Fri, 1 Oct 2021 09:33:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1352944AbhJAJf0 (ORCPT ); Fri, 1 Oct 2021 05:35:26 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40882 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229681AbhJAJfZ (ORCPT ); Fri, 1 Oct 2021 05:35:25 -0400 Received: from bhuna.collabora.co.uk (bhuna.collabora.co.uk [IPv6:2a00:1098:0:82:1000:25:2eeb:e3e3]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 30419C061775 for ; Fri, 1 Oct 2021 02:33:41 -0700 (PDT) Received: from [127.0.0.1] (localhost [127.0.0.1]) (Authenticated sender: gtucker) with ESMTPSA id BBE1C1F4539F Subject: Re: [PATCH v5 6/6] sched/fair: Consider SMT in ASYM_PACKING load balance To: Ricardo Neri , "Peter Zijlstra (Intel)" , Ingo Molnar , Juri Lelli , Vincent Guittot Cc: Srikar Dronamraju , Nicholas Piggin , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Len Brown , Srinivas Pandruvada , Tim Chen , Aubrey Li , "Ravi V. Shankar" , Ricardo Neri , Quentin Perret , "Joel Fernandes (Google)" , linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, Aubrey Li , Daniel Bristot de Oliveira , "Rafael J . Wysocki" , "kernelci-results@groups.io" References: <20210911011819.12184-1-ricardo.neri-calderon@linux.intel.com> <20210911011819.12184-7-ricardo.neri-calderon@linux.intel.com> From: Guillaume Tucker Message-ID: <78608a82-93b8-8036-2bf0-65f53f2f5120@collabora.com> Date: Fri, 1 Oct 2021 11:33:34 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.14.0 MIME-Version: 1.0 In-Reply-To: <20210911011819.12184-7-ricardo.neri-calderon@linux.intel.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Ricardo, Please see the bisection report below about a boot failure on rk3288-rock64. Reports aren't automatically sent to the public while we're trialing new bisection features on kernelci.org but this one looks valid. Some more details can be found here: https://linux.kernelci.org/test/case/id/6155a4b0836c79a98f99a31d/ It looks like some i.MX arm64 platforms also regressed with next-20210920 although it hasn't been verified yet whether that's due to the same commit: https://linux.kernelci.org/test/job/next/branch/master/kernel/next-20210930/plan/baseline/ The x86 platforms don't seem to be impacted though. Please let us know if you need help debugging the issue or if you have a fix to try. Best wishes, Guillaume GitHub: https://github.com/kernelci/kernelci-project/issues/65 ------------------------------------------------------------------------------- * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * This automated bisection report was sent to you on the basis * * that you may be involved with the breaking commit it has * * found. No manual investigation has been done to verify it, * * and the root cause of the problem may be somewhere else. * * * * If you do send a fix, please include this trailer: * * Reported-by: "kernelci.org bot" * * * * Hope this helps! * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * next/master bisection: baseline.login on rk3328-rock64 Summary: Start: 2d02a18f75fc Add linux-next specific files for 20210929 Plain log: https://storage.kernelci.org/next/master/next-20210929/arm64/defconfig+CONFIG_RANDOMIZE_BASE=y/gcc-8/lab-baylibre/baseline-rk3328-rock64.txt HTML log: https://storage.kernelci.org/next/master/next-20210929/arm64/defconfig+CONFIG_RANDOMIZE_BASE=y/gcc-8/lab-baylibre/baseline-rk3328-rock64.html Result: eac6f3841f1d sched/fair: Consider SMT in ASYM_PACKING load balance Checks: revert: PASS verify: PASS Parameters: Tree: next URL: https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git Branch: master Target: rk3328-rock64 CPU arch: arm64 Lab: lab-baylibre Compiler: gcc-8 Config: defconfig+CONFIG_RANDOMIZE_BASE=y Test case: baseline.login Breaking commit found: ------------------------------------------------------------------------------- commit eac6f3841f1dac7b6f43002056b63f44cc1f1543 Author: Ricardo Neri Date: Fri Sep 10 18:18:19 2021 -0700 sched/fair: Consider SMT in ASYM_PACKING load balance On 11/09/2021 03:18, Ricardo Neri wrote: > When deciding to pull tasks in ASYM_PACKING, it is necessary not only to > check for the idle state of the destination CPU, dst_cpu, but also of > its SMT siblings. > > If dst_cpu is idle but its SMT siblings are busy, performance suffers > if it pulls tasks from a medium priority CPU that does not have SMT > siblings. > > Implement asym_smt_can_pull_tasks() to inspect the state of the SMT > siblings of both dst_cpu and the CPUs in the candidate busiest group. > > Cc: Aubrey Li > Cc: Ben Segall > Cc: Daniel Bristot de Oliveira > Cc: Dietmar Eggemann > Cc: Mel Gorman > Cc: Quentin Perret > Cc: Rafael J. Wysocki > Cc: Srinivas Pandruvada > Cc: Steven Rostedt > Cc: Tim Chen > Reviewed-by: Joel Fernandes (Google) > Reviewed-by: Len Brown > Signed-off-by: Ricardo Neri > --- > Changes since v4: > * Use sg_lb_stats::sum_nr_running the idle state of a scheduling group. > (Vincent, Peter) > * Do not even idle CPUs in asym_smt_can_pull_tasks(). (Vincent) > * Updated function documentation and corrected a typo. > > Changes since v3: > * Removed the arch_asym_check_smt_siblings() hook. Discussions with the > powerpc folks showed that this patch should not impact them. Also, more > recent powerpc processor no longer use asym_packing. (PeterZ) > * Removed unnecessary local variable in asym_can_pull_tasks(). (Dietmar) > * Removed unnecessary check for local CPUs when the local group has zero > utilization. (Joel) > * Renamed asym_can_pull_tasks() as asym_smt_can_pull_tasks() to reflect > the fact that it deals with SMT cases. > * Made asym_smt_can_pull_tasks() return false for !CONFIG_SCHED_SMT so > that callers can deal with non-SMT cases. > > Changes since v2: > * Reworded the commit message to reflect updates in code. > * Corrected misrepresentation of dst_cpu as the CPU doing the load > balancing. (PeterZ) > * Removed call to arch_asym_check_smt_siblings() as it is now called in > sched_asym(). > > Changes since v1: > * Don't bailout in update_sd_pick_busiest() if dst_cpu cannot pull > tasks. Instead, reclassify the candidate busiest group, as it > may still be selected. (PeterZ) > * Avoid an expensive and unnecessary call to cpumask_weight() when > determining if a sched_group is comprised of SMT siblings. > (PeterZ). > --- > kernel/sched/fair.c | 94 +++++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 94 insertions(+) > > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > index 26db017c14a3..8d763dd0174b 100644 > --- a/kernel/sched/fair.c > +++ b/kernel/sched/fair.c > @@ -8597,10 +8597,98 @@ group_type group_classify(unsigned int imbalance_pct, > return group_has_spare; > } > > +/** > + * asym_smt_can_pull_tasks - Check whether the load balancing CPU can pull tasks > + * @dst_cpu: Destination CPU of the load balancing > + * @sds: Load-balancing data with statistics of the local group > + * @sgs: Load-balancing statistics of the candidate busiest group > + * @sg: The candidate busiest group > + * > + * Check the state of the SMT siblings of both @sds::local and @sg and decide > + * if @dst_cpu can pull tasks. > + * > + * If @dst_cpu does not have SMT siblings, it can pull tasks if two or more of > + * the SMT siblings of @sg are busy. If only one CPU in @sg is busy, pull tasks > + * only if @dst_cpu has higher priority. > + * > + * If both @dst_cpu and @sg have SMT siblings, and @sg has exactly one more > + * busy CPU than @sds::local, let @dst_cpu pull tasks if it has higher priority. > + * Bigger imbalances in the number of busy CPUs will be dealt with in > + * update_sd_pick_busiest(). > + * > + * If @sg does not have SMT siblings, only pull tasks if all of the SMT siblings > + * of @dst_cpu are idle and @sg has lower priority. > + */ > +static bool asym_smt_can_pull_tasks(int dst_cpu, struct sd_lb_stats *sds, > + struct sg_lb_stats *sgs, > + struct sched_group *sg) > +{ > +#ifdef CONFIG_SCHED_SMT > + bool local_is_smt, sg_is_smt; > + int sg_busy_cpus; > + > + local_is_smt = sds->local->flags & SD_SHARE_CPUCAPACITY; > + sg_is_smt = sg->flags & SD_SHARE_CPUCAPACITY; > + > + sg_busy_cpus = sgs->group_weight - sgs->idle_cpus; > + > + if (!local_is_smt) { > + /* > + * If we are here, @dst_cpu is idle and does not have SMT > + * siblings. Pull tasks if candidate group has two or more > + * busy CPUs. > + */ > + if (sg_is_smt && sg_busy_cpus >= 2) > + return true; > + > + /* > + * @dst_cpu does not have SMT siblings. @sg may have SMT > + * siblings and only one is busy. In such case, @dst_cpu > + * can help if it has higher priority and is idle (i.e., > + * it has no running tasks). > + */ > + return !sds->local_stat.sum_nr_running && > + sched_asym_prefer(dst_cpu, sg->asym_prefer_cpu); > + } > + > + /* @dst_cpu has SMT siblings. */ > + > + if (sg_is_smt) { > + int local_busy_cpus = sds->local->group_weight - > + sds->local_stat.idle_cpus; > + int busy_cpus_delta = sg_busy_cpus - local_busy_cpus; > + > + if (busy_cpus_delta == 1) > + return sched_asym_prefer(dst_cpu, > + sg->asym_prefer_cpu); > + > + return false; > + } > + > + /* > + * @sg does not have SMT siblings. Ensure that @sds::local does not end > + * up with more than one busy SMT sibling and only pull tasks if there > + * are not busy CPUs (i.e., no CPU has running tasks). > + */ > + if (!sds->local_stat.sum_nr_running) > + return sched_asym_prefer(dst_cpu, sg->asym_prefer_cpu); > + > + return false; > +#else > + /* Always return false so that callers deal with non-SMT cases. */ > + return false; > +#endif > +} > + > static inline bool > sched_asym(struct lb_env *env, struct sd_lb_stats *sds, struct sg_lb_stats *sgs, > struct sched_group *group) > { > + /* Only do SMT checks if either local or candidate have SMT siblings */ > + if ((sds->local->flags & SD_SHARE_CPUCAPACITY) || > + (group->flags & SD_SHARE_CPUCAPACITY)) > + return asym_smt_can_pull_tasks(env->dst_cpu, sds, sgs, group); > + > return sched_asym_prefer(env->dst_cpu, group->asym_prefer_cpu); > } > > @@ -9606,6 +9694,12 @@ static struct rq *find_busiest_queue(struct lb_env *env, > nr_running == 1) > continue; > > + /* Make sure we only pull tasks from a CPU of lower priority */ > + if ((env->sd->flags & SD_ASYM_PACKING) && > + sched_asym_prefer(i, env->dst_cpu) && > + nr_running == 1) > + continue; > + > switch (env->migration_type) { > case migrate_load: > /* > 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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E4E1DC433EF for ; Fri, 1 Oct 2021 12:26:41 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 40095611C0 for ; Fri, 1 Oct 2021 12:26:41 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 40095611C0 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=collabora.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=lists.ozlabs.org Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4HLTqz6jl3z3cFS for ; Fri, 1 Oct 2021 22:26:39 +1000 (AEST) Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=collabora.com (client-ip=2a00:1098:0:82:1000:25:2eeb:e3e3; helo=bhuna.collabora.co.uk; envelope-from=guillaume.tucker@collabora.com; receiver=) X-Greylist: delayed 452 seconds by postgrey-1.36 at boromir; Fri, 01 Oct 2021 19:41:24 AEST Received: from bhuna.collabora.co.uk (bhuna.collabora.co.uk [IPv6:2a00:1098:0:82:1000:25:2eeb:e3e3]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4HLQ9J3WbVz2xXN for ; Fri, 1 Oct 2021 19:41:24 +1000 (AEST) Received: from [127.0.0.1] (localhost [127.0.0.1]) (Authenticated sender: gtucker) with ESMTPSA id BBE1C1F4539F Subject: Re: [PATCH v5 6/6] sched/fair: Consider SMT in ASYM_PACKING load balance To: Ricardo Neri , "Peter Zijlstra (Intel)" , Ingo Molnar , Juri Lelli , Vincent Guittot References: <20210911011819.12184-1-ricardo.neri-calderon@linux.intel.com> <20210911011819.12184-7-ricardo.neri-calderon@linux.intel.com> From: Guillaume Tucker Message-ID: <78608a82-93b8-8036-2bf0-65f53f2f5120@collabora.com> Date: Fri, 1 Oct 2021 11:33:34 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.14.0 MIME-Version: 1.0 In-Reply-To: <20210911011819.12184-7-ricardo.neri-calderon@linux.intel.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Mailman-Approved-At: Fri, 01 Oct 2021 22:25:51 +1000 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Len Brown , "Rafael J . Wysocki" , Srikar Dronamraju , "kernelci-results@groups.io" , "Ravi V. Shankar" , linuxppc-dev@lists.ozlabs.org, Aubrey Li , Nicholas Piggin , Ricardo Neri , Steven Rostedt , Quentin Perret , Ben Segall , Mel Gorman , Daniel Bristot de Oliveira , Srinivas Pandruvada , "Joel Fernandes \(Google\)" , Tim Chen , Dietmar Eggemann , linux-kernel@vger.kernel.org, Aubrey Li Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" Hi Ricardo, Please see the bisection report below about a boot failure on rk3288-rock64. Reports aren't automatically sent to the public while we're trialing new bisection features on kernelci.org but this one looks valid. Some more details can be found here: https://linux.kernelci.org/test/case/id/6155a4b0836c79a98f99a31d/ It looks like some i.MX arm64 platforms also regressed with next-20210920 although it hasn't been verified yet whether that's due to the same commit: https://linux.kernelci.org/test/job/next/branch/master/kernel/next-20210930/plan/baseline/ The x86 platforms don't seem to be impacted though. Please let us know if you need help debugging the issue or if you have a fix to try. Best wishes, Guillaume GitHub: https://github.com/kernelci/kernelci-project/issues/65 ------------------------------------------------------------------------------- * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * This automated bisection report was sent to you on the basis * * that you may be involved with the breaking commit it has * * found. No manual investigation has been done to verify it, * * and the root cause of the problem may be somewhere else. * * * * If you do send a fix, please include this trailer: * * Reported-by: "kernelci.org bot" * * * * Hope this helps! * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * next/master bisection: baseline.login on rk3328-rock64 Summary: Start: 2d02a18f75fc Add linux-next specific files for 20210929 Plain log: https://storage.kernelci.org/next/master/next-20210929/arm64/defconfig+CONFIG_RANDOMIZE_BASE=y/gcc-8/lab-baylibre/baseline-rk3328-rock64.txt HTML log: https://storage.kernelci.org/next/master/next-20210929/arm64/defconfig+CONFIG_RANDOMIZE_BASE=y/gcc-8/lab-baylibre/baseline-rk3328-rock64.html Result: eac6f3841f1d sched/fair: Consider SMT in ASYM_PACKING load balance Checks: revert: PASS verify: PASS Parameters: Tree: next URL: https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git Branch: master Target: rk3328-rock64 CPU arch: arm64 Lab: lab-baylibre Compiler: gcc-8 Config: defconfig+CONFIG_RANDOMIZE_BASE=y Test case: baseline.login Breaking commit found: ------------------------------------------------------------------------------- commit eac6f3841f1dac7b6f43002056b63f44cc1f1543 Author: Ricardo Neri Date: Fri Sep 10 18:18:19 2021 -0700 sched/fair: Consider SMT in ASYM_PACKING load balance On 11/09/2021 03:18, Ricardo Neri wrote: > When deciding to pull tasks in ASYM_PACKING, it is necessary not only to > check for the idle state of the destination CPU, dst_cpu, but also of > its SMT siblings. > > If dst_cpu is idle but its SMT siblings are busy, performance suffers > if it pulls tasks from a medium priority CPU that does not have SMT > siblings. > > Implement asym_smt_can_pull_tasks() to inspect the state of the SMT > siblings of both dst_cpu and the CPUs in the candidate busiest group. > > Cc: Aubrey Li > Cc: Ben Segall > Cc: Daniel Bristot de Oliveira > Cc: Dietmar Eggemann > Cc: Mel Gorman > Cc: Quentin Perret > Cc: Rafael J. Wysocki > Cc: Srinivas Pandruvada > Cc: Steven Rostedt > Cc: Tim Chen > Reviewed-by: Joel Fernandes (Google) > Reviewed-by: Len Brown > Signed-off-by: Ricardo Neri > --- > Changes since v4: > * Use sg_lb_stats::sum_nr_running the idle state of a scheduling group. > (Vincent, Peter) > * Do not even idle CPUs in asym_smt_can_pull_tasks(). (Vincent) > * Updated function documentation and corrected a typo. > > Changes since v3: > * Removed the arch_asym_check_smt_siblings() hook. Discussions with the > powerpc folks showed that this patch should not impact them. Also, more > recent powerpc processor no longer use asym_packing. (PeterZ) > * Removed unnecessary local variable in asym_can_pull_tasks(). (Dietmar) > * Removed unnecessary check for local CPUs when the local group has zero > utilization. (Joel) > * Renamed asym_can_pull_tasks() as asym_smt_can_pull_tasks() to reflect > the fact that it deals with SMT cases. > * Made asym_smt_can_pull_tasks() return false for !CONFIG_SCHED_SMT so > that callers can deal with non-SMT cases. > > Changes since v2: > * Reworded the commit message to reflect updates in code. > * Corrected misrepresentation of dst_cpu as the CPU doing the load > balancing. (PeterZ) > * Removed call to arch_asym_check_smt_siblings() as it is now called in > sched_asym(). > > Changes since v1: > * Don't bailout in update_sd_pick_busiest() if dst_cpu cannot pull > tasks. Instead, reclassify the candidate busiest group, as it > may still be selected. (PeterZ) > * Avoid an expensive and unnecessary call to cpumask_weight() when > determining if a sched_group is comprised of SMT siblings. > (PeterZ). > --- > kernel/sched/fair.c | 94 +++++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 94 insertions(+) > > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > index 26db017c14a3..8d763dd0174b 100644 > --- a/kernel/sched/fair.c > +++ b/kernel/sched/fair.c > @@ -8597,10 +8597,98 @@ group_type group_classify(unsigned int imbalance_pct, > return group_has_spare; > } > > +/** > + * asym_smt_can_pull_tasks - Check whether the load balancing CPU can pull tasks > + * @dst_cpu: Destination CPU of the load balancing > + * @sds: Load-balancing data with statistics of the local group > + * @sgs: Load-balancing statistics of the candidate busiest group > + * @sg: The candidate busiest group > + * > + * Check the state of the SMT siblings of both @sds::local and @sg and decide > + * if @dst_cpu can pull tasks. > + * > + * If @dst_cpu does not have SMT siblings, it can pull tasks if two or more of > + * the SMT siblings of @sg are busy. If only one CPU in @sg is busy, pull tasks > + * only if @dst_cpu has higher priority. > + * > + * If both @dst_cpu and @sg have SMT siblings, and @sg has exactly one more > + * busy CPU than @sds::local, let @dst_cpu pull tasks if it has higher priority. > + * Bigger imbalances in the number of busy CPUs will be dealt with in > + * update_sd_pick_busiest(). > + * > + * If @sg does not have SMT siblings, only pull tasks if all of the SMT siblings > + * of @dst_cpu are idle and @sg has lower priority. > + */ > +static bool asym_smt_can_pull_tasks(int dst_cpu, struct sd_lb_stats *sds, > + struct sg_lb_stats *sgs, > + struct sched_group *sg) > +{ > +#ifdef CONFIG_SCHED_SMT > + bool local_is_smt, sg_is_smt; > + int sg_busy_cpus; > + > + local_is_smt = sds->local->flags & SD_SHARE_CPUCAPACITY; > + sg_is_smt = sg->flags & SD_SHARE_CPUCAPACITY; > + > + sg_busy_cpus = sgs->group_weight - sgs->idle_cpus; > + > + if (!local_is_smt) { > + /* > + * If we are here, @dst_cpu is idle and does not have SMT > + * siblings. Pull tasks if candidate group has two or more > + * busy CPUs. > + */ > + if (sg_is_smt && sg_busy_cpus >= 2) > + return true; > + > + /* > + * @dst_cpu does not have SMT siblings. @sg may have SMT > + * siblings and only one is busy. In such case, @dst_cpu > + * can help if it has higher priority and is idle (i.e., > + * it has no running tasks). > + */ > + return !sds->local_stat.sum_nr_running && > + sched_asym_prefer(dst_cpu, sg->asym_prefer_cpu); > + } > + > + /* @dst_cpu has SMT siblings. */ > + > + if (sg_is_smt) { > + int local_busy_cpus = sds->local->group_weight - > + sds->local_stat.idle_cpus; > + int busy_cpus_delta = sg_busy_cpus - local_busy_cpus; > + > + if (busy_cpus_delta == 1) > + return sched_asym_prefer(dst_cpu, > + sg->asym_prefer_cpu); > + > + return false; > + } > + > + /* > + * @sg does not have SMT siblings. Ensure that @sds::local does not end > + * up with more than one busy SMT sibling and only pull tasks if there > + * are not busy CPUs (i.e., no CPU has running tasks). > + */ > + if (!sds->local_stat.sum_nr_running) > + return sched_asym_prefer(dst_cpu, sg->asym_prefer_cpu); > + > + return false; > +#else > + /* Always return false so that callers deal with non-SMT cases. */ > + return false; > +#endif > +} > + > static inline bool > sched_asym(struct lb_env *env, struct sd_lb_stats *sds, struct sg_lb_stats *sgs, > struct sched_group *group) > { > + /* Only do SMT checks if either local or candidate have SMT siblings */ > + if ((sds->local->flags & SD_SHARE_CPUCAPACITY) || > + (group->flags & SD_SHARE_CPUCAPACITY)) > + return asym_smt_can_pull_tasks(env->dst_cpu, sds, sgs, group); > + > return sched_asym_prefer(env->dst_cpu, group->asym_prefer_cpu); > } > > @@ -9606,6 +9694,12 @@ static struct rq *find_busiest_queue(struct lb_env *env, > nr_running == 1) > continue; > > + /* Make sure we only pull tasks from a CPU of lower priority */ > + if ((env->sd->flags & SD_ASYM_PACKING) && > + sched_asym_prefer(i, env->dst_cpu) && > + nr_running == 1) > + continue; > + > switch (env->migration_type) { > case migrate_load: > /* >