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Message-ID: <f8ab9995-72a3-4367-68bf-a74423167daf@huawei.com>
Date: Tue, 15 Aug 2023 19:16:17 +0800
From: Yicong Yang <yangyicong@...wei.com>
To: <peterz@...radead.org>
CC: <yangyicong@...ilicon.com>, <rostedt@...dmis.org>,
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Subject: Re: [PATCH v9 0/2] sched/fair: Scan cluster before scanning LLC in
wake-up path
Hi Peter,
A gentle ping for this. Any further comment?
Thanks.
On 2023/7/19 17:28, Yicong Yang wrote:
> From: Yicong Yang <yangyicong@...ilicon.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")
>
> Since we're using sd->groups->flags to determine a cluster, core should ensure
> the flags set correctly on domain generation. This is done by [*].
>
> [*] https://lore.kernel.org/all/20230713013133.2314153-1-yu.c.chen@intel.com/
>
> Change since v8:
> - Peter find cpus_share_lowest_cache() is weired so fallback to cpus_share_resources()
> suggested in v4
> - Use sd->groups->flags to find the cluster when scanning, save one per-cpu pointer
> - Fix sched_cluster_active enabled incorrectly on domain degeneration
> - Use sched_cluster_active to avoid repeated check on non-cluster machines, per Gautham
> Link: https://lore.kernel.org/all/20230530070253.33306-1-yangyicong@huawei.com/
>
> Change since v7:
> - Optimize by choosing prev_cpu/recent_used_cpu when possible after failed to
> scanning for an idle CPU in cluster/LLC. Thanks Chen Yu for testing on Jacobsville
> Link: https://lore.kernel.org/all/20220915073423.25535-1-yangyicong@huawei.com/
>
> 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 cpus_share_resources 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 | 59 +++++++++++++++++++++++++++++++---
> kernel/sched/sched.h | 2 ++
> kernel/sched/topology.c | 25 ++++++++++++++
> 6 files changed, 107 insertions(+), 6 deletions(-)
>
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