Return-Path: Received: from mx142.netapp.com ([216.240.21.19]:5603 "EHLO mx142.netapp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752250AbcIAVPz (ORCPT ); Thu, 1 Sep 2016 17:15:55 -0400 Subject: Re: [PATCH] sunrpc: queue work on system_power_efficient_wq To: Chunyan Zhang , , , References: <1472715026-11397-1-git-send-email-zhang.lyra@gmail.com> CC: , , , From: Anna Schumaker Message-ID: <544e309c-9893-a0ed-ab8a-ccbf5d342dc6@Netapp.com> Date: Thu, 1 Sep 2016 14:46:35 -0400 MIME-Version: 1.0 In-Reply-To: <1472715026-11397-1-git-send-email-zhang.lyra@gmail.com> Content-Type: text/plain; charset="utf-8" Sender: linux-nfs-owner@vger.kernel.org List-ID: On 09/01/2016 03:30 AM, Chunyan Zhang wrote: > From: Ke Wang > > 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 > --- > 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); > } > > >