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Date:   Mon, 26 Sep 2022 22:52:12 +0800
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Subject: Re: [RESEND PATCH v7 0/2] sched/fair: Scan cluster before scanning
 LLC in wake-up path
To:     peterz@infradead.org
Cc:     gautham.shenoy@amd.com, vincent.guittot@linaro.org,
        tim.c.chen@linux.intel.com, dietmar.eggemann@arm.com,
        rostedt@goodmis.org, bsegall@google.com, bristot@redhat.com,
        prime.zeng@huawei.com, yangyicong@hisilicon.com,
        jonathan.cameron@huawei.com, ego@linux.vnet.ibm.com,
        srikar@linux.vnet.ibm.com, linuxarm@huawei.com, 21cnbao@gmail.com,
        juri.lelli@redhat.com, mingo@redhat.com, guodong.xu@linaro.org,
        hesham.almatary@huawei.com, john.garry@huawei.com,
        shenyang39@huawei.com, kprateek.nayak@amd.com, yu.c.chen@intel.com,
        wuyun.abel@bytedance.com, Yicong Yang <yangyicong@huawei.com>,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org
References: <20220915073423.25535-1-yangyicong@huawei.com>
From:   Yicong Yang <yangyccccc@gmail.com>
In-Reply-To: <20220915073423.25535-1-yangyicong@huawei.com>
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Hi Peter,

Does it still have a chance for 6.1?

It should be stable for now since I got no new comment for this whole review cycle and
it can still be applied cleanly on tip/sched/core.

However appreciation for any comment if there're!

Thanks.

On 9/15/2022 3:34 PM, Yicong Yang wrote:
> From: Yicong Yang <yangyicong@hisilicon.com>
> 
> This is the follow-up work to support cluster scheduler. Previously
> we have added cluster level in the scheduler for both ARM64[1] and
> X86[2] to support load balance between clusters to bring more memory
> bandwidth and decrease cache contention. This patchset, on the other
> hand, takes care of wake-up path by giving CPUs within the same cluster
> a try before scanning the whole LLC to benefit those tasks communicating
> with each other.
> 
> [1] 778c558f49a2 ("sched: Add cluster scheduler level in core and related Kconfig for ARM64")
> [2] 66558b730f25 ("sched: Add cluster scheduler level for x86")
> 
> Change for RESEND:
> - Collect tag from Chen Yu and rebase on the latest tip/sched/core. Thanks.
> Link: https://lore.kernel.org/lkml/20220822073610.27205-1-yangyicong@huawei.com/
> 
> Change since v6:
> - rebase on 6.0-rc1
> Link: https://lore.kernel.org/lkml/20220726074758.46686-1-yangyicong@huawei.com/
> 
> Change since v5:
> - Improve patch 2 according to Peter's suggestion:
>   - use sched_cluster_active to indicate whether cluster is active
>   - consider SMT case and use wrap iteration when scanning cluster
> - Add Vincent's tag
> Thanks.
> Link: https://lore.kernel.org/lkml/20220720081150.22167-1-yangyicong@hisilicon.com/
> 
> Change since v4:
> - rename cpus_share_resources to cpus_share_lowest_cache to be more informative, per Tim
> - return -1 when nr==0 in scan_cluster(), per Abel
> Thanks!
> Link: https://lore.kernel.org/lkml/20220609120622.47724-1-yangyicong@hisilicon.com/
> 
> Change since v3:
> - fix compile error when !CONFIG_SCHED_CLUSTER, reported by lkp test.
> Link: https://lore.kernel.org/lkml/20220608095758.60504-1-yangyicong@hisilicon.com/
> 
> Change since v2:
> - leverage SIS_PROP to suspend redundant scanning when LLC is overloaded
> - remove the ping-pong suppression
> - address the comment from Tim, thanks.
> Link: https://lore.kernel.org/lkml/20220126080947.4529-1-yangyicong@hisilicon.com/
> 
> Change since v1:
> - regain the performance data based on v5.17-rc1
> - rename cpus_share_cluster to cpus_share_resources per Vincent and Gautham, thanks!
> Link: https://lore.kernel.org/lkml/20211215041149.73171-1-yangyicong@hisilicon.com/
> 
> Barry Song (2):
>   sched: Add per_cpu cluster domain info and cpus_share_lowest_cache API
>   sched/fair: Scan cluster before scanning LLC in wake-up path
> 
>  include/linux/sched/sd_flags.h |  7 +++++++
>  include/linux/sched/topology.h |  8 +++++++-
>  kernel/sched/core.c            | 12 ++++++++++++
>  kernel/sched/fair.c            | 30 +++++++++++++++++++++++++++---
>  kernel/sched/sched.h           |  3 +++
>  kernel/sched/topology.c        | 25 +++++++++++++++++++++++++
>  6 files changed, 81 insertions(+), 4 deletions(-)
>