Re: [PATCH] fpga: dfl: fme: Fix cpu hotplug issue in performance reporting

Re: [PATCH] fpga: dfl: fme: Fix cpu hotplug issue in performance reporting

[kajoljain]

On 6/28/21 3:47 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.
> 

Adding stable@vger.kernel.org in cc list as suggested by Moritz Fischer.

Thanks,
Kajol Jain

> Fixes: 724142f8c42a ("fpga: dfl: fme: add performance reporting support")
> Tested-by: Xu Yilun <yilun.xu@intel.com>
> Signed-off-by: Kajol Jain <kjain@linux.ibm.com>
> ---
>  drivers/fpga/dfl-fme-perf.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> ---
> Changelog:
> - 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..b9a54583e505 100644
> --- a/drivers/fpga/dfl-fme-perf.c
> +++ b/drivers/fpga/dfl-fme-perf.c
> @@ -953,6 +953,10 @@ static int fme_perf_offline_cpu(unsigned int cpu, struct hlist_node *node)
>  		return 0;
>  
>  	priv->cpu = target;
> +
> +	/* Migrate fme_perf pmu events to the new target cpu */
> +	perf_pmu_migrate_context(&priv->pmu, cpu, target);
> +
>  	return 0;
>  }
>  
> 

Re: [PATCH] fpga: dfl: fme: Fix cpu hotplug issue in performance reporting

[Greg KH]

On Tue, Jun 29, 2021 at 12:45:20PM +0530, kajoljain wrote:
> 
> 
> On 6/28/21 3:47 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.
> > 
> 
> Adding stable@vger.kernel.org in cc list as suggested by Moritz Fischer.


<formletter>

This is not the correct way to submit patches for inclusion in the
stable kernel tree.  Please read:
    https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html
for how to do this properly.

</formletter>

Re: [PATCH] fpga: dfl: fme: Fix cpu hotplug issue in performance reporting

[kajoljain]

On 6/29/21 12:57 PM, Greg KH wrote:
> On Tue, Jun 29, 2021 at 12:45:20PM +0530, kajoljain wrote:
>>
>>
>> On 6/28/21 3:47 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.
>>>
>>
>> Adding stable@vger.kernel.org in cc list as suggested by Moritz Fischer.
> 
> 
> <formletter>
> 
> This is not the correct way to submit patches for inclusion in the
> stable kernel tree.  Please read:
>     https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html
> for how to do this properly.

Thanks Greg for pointing it, I will take care in my next version.

Thanks,
Kajol Jain

> 
> </formletter>
>