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Shenoy" , Vincent Guittot , Juri Lelli , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Valentin Schneider , Madadi Vineeth Reddy , Hillf Danton , Shrikanth Hegde , Jianyong Wu , Yangyu Chen , Tingyin Duan , Vern Hao , Len Brown , Aubrey Li , Zhao Liu , Chen Yu , Chen Yu , Libo Chen , Adam Li , Tim Chen , linux-kernel@vger.kernel.org Subject: Re: [PATCH 10/19] sched/fair: Prioritize tasks preferring destination LLC during balancing Message-ID: <20251024093258.GA1630077@bytedance> References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Hi Tim, On Sat, Oct 11, 2025 at 11:24:47AM -0700, Tim Chen wrote: > @@ -10849,11 +10849,45 @@ static void record_sg_llc_stats(struct lb_env *env, > if (unlikely(READ_ONCE(sd_share->capacity) != sgs->group_capacity)) > WRITE_ONCE(sd_share->capacity, sgs->group_capacity); > } > + > +/* > + * Do LLC balance on sched group that contains LLC, and have tasks preferring > + * to run on LLC in idle dst_cpu. > + */ > +static inline bool llc_balance(struct lb_env *env, struct sg_lb_stats *sgs, > + struct sched_group *group) > +{ > + struct sched_domain *child = env->sd->child; > + int llc; > + > + if (!sched_cache_enabled()) > + return false; > + > + if (env->sd->flags & SD_SHARE_LLC) > + return false; > + > + /* only care about task migration among LLCs */ > + if (child && !(child->flags & SD_SHARE_LLC)) > + return false; > + > + llc = llc_idx(env->dst_cpu); > + if (sgs->nr_pref_llc[llc] > 0 && > + can_migrate_llc(env->src_cpu, env->dst_cpu, 0, true) == mig_llc) llc_balance() is called from update_sg_lb_stats() and at that time, env->src_cpu is not determined yet so should not be used here? > + return true; > + > + return false; > +}