From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Subject: Re: [PATCH 1/1] Drivers: net-next: hyperv: Increase the size of the sendbuf region Date: Thu, 31 Jul 2014 21:59:07 -0700 (PDT) Message-ID: <20140731.215907.860867918938148695.davem@davemloft.net> References: <1406770549-29982-1-git-send-email-kys@microsoft.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: olaf@aepfle.de, netdev@vger.kernel.org, jasowang@redhat.com, linux-kernel@vger.kernel.org, apw@canonical.com, devel@linuxdriverproject.org To: kys@microsoft.com Return-path: In-Reply-To: <1406770549-29982-1-git-send-email-kys@microsoft.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: driverdev-devel-bounces@linuxdriverproject.org Sender: driverdev-devel-bounces@linuxdriverproject.org List-Id: netdev.vger.kernel.org From: "K. Y. Srinivasan" Date: Wed, 30 Jul 2014 18:35:49 -0700 > For forwarding scenarios, it will be useful to allocate larger > sendbuf. Make the necessary adjustments to permit this. > > Signed-off-by: K. Y. Srinivasan This needs more information. You're increasing the size by 16 times, 1MB --> 16MB, thus less cache locality. You're also now using vmalloc() memory, thus more TLB misses and thrashing. This must have a negative impact on performance, and you have to test for that and quantify it when making a change as serious as this one. You also haven't gone into detail as to why forwarding scenerios require more buffer space, than say thousands of local sockets sending bulk TCP data. I'm not applying this, it needs a lot more work.