netdev - Re: 答复: [PATCH] sunrpc: queue work on system_power_efficient

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Date:   Tue, 20 Sep 2016 13:03:45 +0800
From:   Chunyan Zhang <zhang.lyra@...il.com>
To:     Ke Wang (王科) <Ke.Wang@...eadtrum.com>
Cc:     Anna Schumaker <Anna.Schumaker@...app.com>,
        "trond.myklebust@...marydata.com" <trond.myklebust@...marydata.com>,
        "davem@...emloft.net" <davem@...emloft.net>,
        "linux-nfs@...r.kernel.org" <linux-nfs@...r.kernel.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: 答复: [PATCH] sunrpc: queue work on system_power_efficient_wq

Resend behalf on Ke Wang.

Thanks,
Chunyan

On 20 September 2016 at 10:33, Ke Wang (王科) <Ke.Wang@...eadtrum.com> wrote:
> May I have any comments for this patch?
> or
> This patch can be merged directly into next release?
>
> Thanks,
> Ke
> ________________________________________
> 发件人: Anna Schumaker <Anna.Schumaker@...app.com>
> 发送时间: 2016年9月2日 2:46
> 收件人: Chunyan Zhang; trond.myklebust@...marydata.com; anna.schumaker@...app.com; davem@...emloft.net
> 抄送: linux-nfs@...r.kernel.org; netdev@...r.kernel.org; linux-kernel@...r.kernel.org; Ke Wang (王科)
> 主题: Re: [PATCH] sunrpc: queue work on system_power_efficient_wq
>
> On 09/01/2016 03:30 AM, Chunyan Zhang wrote:
>> From: Ke Wang <ke.wang@...eadtrum.com>
>>
>> sunrpc uses workqueue to clean cache regulary. There is no real dependency
>> of executing work on the cpu which queueing it.
>>
>> On a idle system, especially for a heterogeneous systems like big.LITTLE,
>> it is observed that the big idle cpu was woke up many times just to service
>> this work, which against the principle of power saving. It would be better
>> if we can schedule it on a cpu which the scheduler believes to be the most
>> appropriate one.
>>
>> After apply this patch, system_wq will be replaced by
>> system_power_efficient_wq for sunrpc. This functionality is enabled when
>> CONFIG_WQ_POWER_EFFICIENT is selected.
>
> Makes sense to me, but I'm a little surprised that there isn't a "schedule_delayed_power_efficient_work()" function to match how the normal workqueue is used.
>
> Thanks,
> Anna
>
>>
>> Signed-off-by: Ke Wang <ke.wang@...eadtrum.com>
>> ---
>>  net/sunrpc/cache.c | 5 +++--
>>  1 file changed, 3 insertions(+), 2 deletions(-)
>>
>> diff --git a/net/sunrpc/cache.c b/net/sunrpc/cache.c
>> index 4d8e11f..8aabe12 100644
>> --- a/net/sunrpc/cache.c
>> +++ b/net/sunrpc/cache.c
>> @@ -353,7 +353,7 @@ void sunrpc_init_cache_detail(struct cache_detail *cd)
>>       spin_unlock(&cache_list_lock);
>>
>>       /* start the cleaning process */
>> -     schedule_delayed_work(&cache_cleaner, 0);
>> +     queue_delayed_work(system_power_efficient_wq, &cache_cleaner, 0);
>>  }
>>  EXPORT_SYMBOL_GPL(sunrpc_init_cache_detail);
>>
>> @@ -476,7 +476,8 @@ static void do_cache_clean(struct work_struct *work)
>>               delay = 0;
>>
>>       if (delay)
>> -             schedule_delayed_work(&cache_cleaner, delay);
>> +             queue_delayed_work(system_power_efficient_wq,
>> +                                &cache_cleaner, delay);
>>  }
>>
>>
>>
>