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[73.241.150.58]) by smtp.gmail.com with ESMTPSA id n205sm733624pfd.50.2020.05.19.20.18.20 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 19 May 2020 20:18:21 -0700 (PDT) Subject: Re: [PATCH v1 01/25] net: core: device_rename: Use rwsem instead of a seqcount To: David Miller , tglx@linutronix.de Cc: stephen@networkplumber.org, a.darwish@linutronix.de, peterz@infradead.org, mingo@redhat.com, will@kernel.org, paulmck@kernel.org, bigeasy@linutronix.de, rostedt@goodmis.org, linux-kernel@vger.kernel.org, kuba@kernel.org, netdev@vger.kernel.org References: <87v9kr5zt7.fsf@nanos.tec.linutronix.de> <20200519161141.5fbab730@hermes.lan> <87lfln5w61.fsf@nanos.tec.linutronix.de> <20200519.195722.1091264300612213554.davem@davemloft.net> From: Eric Dumazet Message-ID: <886041df-d889-3d88-59fe-e190d15f9c98@gmail.com> Date: Tue, 19 May 2020 20:18:19 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.6.0 MIME-Version: 1.0 In-Reply-To: <20200519.195722.1091264300612213554.davem@davemloft.net> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 5/19/20 7:57 PM, David Miller wrote: > From: Thomas Gleixner > Date: Wed, 20 May 2020 01:42:30 +0200 > >> Stephen Hemminger writes: >>> On Wed, 20 May 2020 00:23:48 +0200 >>> Thomas Gleixner wrote: >>>> No. We did not. -ENOTESTCASE >>> >>> Please try, it isn't that hard.. >>> >>> # time for ((i=0;i<1000;i++)); do ip li add dev dummy$i type dummy; done >>> >>> real 0m17.002s >>> user 0m1.064s >>> sys 0m0.375s >> >> And that solves the incorrectness of the current code in which way? > > You mentioned that there wasn't a test case, he gave you one to try. > I do not think this would ever use device rename, nor netdev_get_name() None of this stuff is fast path really. # time for ((i=1;i<1000;i++)); do ip li add dev dummy$i type dummy; done real 0m1.127s user 0m0.270s sys 0m1.039s