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[204.195.22.127]) by smtp.gmail.com with ESMTPSA id z8sm61913492pgz.3.2019.04.15.08.38.37 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Mon, 15 Apr 2019 08:38:37 -0700 (PDT) Date: Mon, 15 Apr 2019 08:38:34 -0700 From: Stephen Hemminger To: "Ananyev, Konstantin" Cc: Honnappa Nagarahalli , "paulmck@linux.ibm.com" , "Kovacevic, Marko" , "dev@dpdk.org" , "Gavin Hu (Arm Technology China)" , Dharmik Thakkar , Malvika Gupta , nd Message-ID: <20190415083834.31b38ed3@shemminger-XPS-13-9360> In-Reply-To: <2601191342CEEE43887BDE71AB9772580148A97E53@irsmsx105.ger.corp.intel.com> References: <20181122033055.3431-1-honnappa.nagarahalli@arm.com> <20190412202039.46902-1-honnappa.nagarahalli@arm.com> <20190412202039.46902-2-honnappa.nagarahalli@arm.com> <20190412150650.3709358e@shemminger-XPS-13-9360> <20190412160629.670eacd1@shemminger-XPS-13-9360> <2601191342CEEE43887BDE71AB9772580148A97E53@irsmsx105.ger.corp.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Subject: Re: [dpdk-dev] [PATCH v5 1/3] rcu: add RCU library supporting QSBR mechanism X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" Message-ID: <20190415153834.0RH0lGBIEMU3VOKmwSNE1rggERVPzVPchR1yhEMtZgQ@z> On Mon, 15 Apr 2019 12:24:47 +0000 "Ananyev, Konstantin" wrote: > > -----Original Message----- > > From: Stephen Hemminger [mailto:stephen@networkplumber.org] > > Sent: Saturday, April 13, 2019 12:06 AM > > To: Honnappa Nagarahalli > > Cc: Ananyev, Konstantin ; paulmck@linux.ibm.com; Kovacevic, Marko ; > > dev@dpdk.org; Gavin Hu (Arm Technology China) ; Dharmik Thakkar ; Malvika Gupta > > ; nd > > Subject: Re: [PATCH v5 1/3] rcu: add RCU library supporting QSBR mechanism > > > > On Fri, 12 Apr 2019 22:24:45 +0000 > > Honnappa Nagarahalli wrote: > > > > > > > > > > On Fri, 12 Apr 2019 15:20:37 -0500 > > > > Honnappa Nagarahalli wrote: > > > > > > > > > Add RCU library supporting quiescent state based memory reclamation > > > > method. > > > > > This library helps identify the quiescent state of the reader threads > > > > > so that the writers can free the memory associated with the lock less > > > > > data structures. > > > > > > > > > > Signed-off-by: Honnappa Nagarahalli > > > > > Reviewed-by: Steve Capper > > > > > Reviewed-by: Gavin Hu > > > > > Reviewed-by: Ola Liljedahl > > > > > Acked-by: Konstantin Ananyev > > > > > > > > After evaluating long term API/ABI issues, I think you need to get rid of almost > > > > all use of inline and visible structures. Yes it might be marginally slower, but > > > > you thank me the first time you have to fix something. > > > > > > > Agree, I was planning on another version to address this (I am yet to take a look at your patch addressing the ABI). > > > The structure visibility definitely needs to be addressed. > > > For the inline functions, is the plan to convert all the inline functions in DPDK? If yes, I think we need to consider the performance > > difference. May be consider L3-fwd application, change all the inline functions in its path and run a test? > > > > Every function that is not in the direct datapath should not be inline. > > Exceptions or things like rx/tx burst, ring enqueue/dequeue, and packet alloc/free > > Plus synchronization routines: spin/rwlock/barrier, etc. > I think rcu should be one of such exceptions - it is just another synchronization mechanism after all > (just a bit more sophisticated). > Konstantin If you look at the other userspace RCU, you wil see that the only inlines are the rcu_read_lock,rcu_read_unlock and rcu_reference/rcu_assign_pointer. The synchronization logic is all real functions.