linux-kernel - Re: [PATCH v3] fpga: dfl: fme: Fix cpu hotplug issue in performance reporting

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Message-ID: <61495dc0-f496-992c-1d2a-9229a04e6e44@linux.ibm.com>
Date:   Mon, 2 Aug 2021 13:15:00 +0530
From:   kajoljain <kjain@...ux.ibm.com>
To:     will@...nel.org, hao.wu@...el.com, mark.rutland@....com
Cc:     trix@...hat.com, yilun.xu@...el.com, mdf@...nel.org,
        linux-fpga@...r.kernel.org, maddy@...ux.ibm.com,
        atrajeev@...ux.vnet.ibm.com, linux-kernel@...r.kernel.org,
        linuxppc-dev@...ts.ozlabs.org, rnsastry@...ux.ibm.com,
        linux-perf-users@...r.kernel.org, stable@...r.kernel.org
Subject: Re: [PATCH v3] fpga: dfl: fme: Fix cpu hotplug issue in performance
 reporting



On 7/13/21 1:12 PM, Kajol Jain wrote:
> The performance reporting driver added cpu hotplug
> feature but it didn't add pmu migration call in cpu
> offline function.
> This can create an issue incase the current designated
> cpu being used to collect fme pmu data got offline,
> as based on current code we are not migrating fme pmu to
> new target cpu. Because of that perf will still try to
> fetch data from that offline cpu and hence we will not
> get counter data.
> 
> Patch fixed this issue by adding pmu_migrate_context call
> in fme_perf_offline_cpu function.
> 
> Fixes: 724142f8c42a ("fpga: dfl: fme: add performance reporting support")
> Tested-by: Xu Yilun <yilun.xu@...el.com>
> Acked-by: Wu Hao <hao.wu@...el.com>
> Signed-off-by: Kajol Jain <kjain@...ux.ibm.com>
> Cc: stable@...r.kernel.org
> ---

Any update on this patch? Please let me know if any changes required.

Thanks,
Kajol Jain

>  drivers/fpga/dfl-fme-perf.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> ---
> Changelog:
> v2 -> v3:
> - Added Acked-by tag
> - Removed comment as suggested by Wu Hao
> - Link to patch v2: https://lkml.org/lkml/2021/7/9/143
> 
> v1 -> v2:
> - Add stable@...r.kernel.org in cc list
> - Link to patch v1: https://lkml.org/lkml/2021/6/28/275
> 
> RFC -> PATCH v1
> - Remove RFC tag
> - Did nits changes on subject and commit message as suggested by Xu Yilun
> - Added Tested-by tag
> - Link to rfc patch: https://lkml.org/lkml/2021/6/28/112
> ---
> 
> diff --git a/drivers/fpga/dfl-fme-perf.c b/drivers/fpga/dfl-fme-perf.c
> index 4299145ef347..587c82be12f7 100644
> --- a/drivers/fpga/dfl-fme-perf.c
> +++ b/drivers/fpga/dfl-fme-perf.c
> @@ -953,6 +953,8 @@ static int fme_perf_offline_cpu(unsigned int cpu, struct hlist_node *node)
>  		return 0;
>  
>  	priv->cpu = target;
> +	perf_pmu_migrate_context(&priv->pmu, cpu, target);
> +
>  	return 0;
>  }
>  
>