Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751038AbaKYS1Y (ORCPT ); Tue, 25 Nov 2014 13:27:24 -0500 Received: from shards.monkeyblade.net ([149.20.54.216]:36571 "EHLO shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750841AbaKYS1X (ORCPT ); Tue, 25 Nov 2014 13:27:23 -0500 Date: Tue, 25 Nov 2014 13:27:17 -0500 (EST) Message-Id: <20141125.132717.122094133335261929.davem@davemloft.net> To: pagupta@redhat.com Cc: linux-kernel@vger.kernel.org, netdev@vger.kernel.org, jasowang@redhat.com, dgibson@redhat.com, vfalico@gmail.com, edumazet@google.com, vyasevic@redhat.com, hkchu@google.com, xemul@parallels.com, therbert@google.com, bhutchings@solarflare.com, xii@google.com, stephen@networkplumber.org, jiri@resnulli.us, sergei.shtylyov@cogentembedded.com Subject: Re: [PATCH v2 net-next 3/3] tuntap: reduce the size of tun_struct by using flex array. From: David Miller In-Reply-To: <1416854044-10124-1-git-send-email-pagupta@redhat.com> References: <1416854044-10124-1-git-send-email-pagupta@redhat.com> X-Mailer: Mew version 6.5 on Emacs 24.1 / Mule 6.0 (HANACHIRUSATO) Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.5.7 (shards.monkeyblade.net [149.20.54.216]); Tue, 25 Nov 2014 10:27:21 -0800 (PST) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Pankaj Gupta Date: Tue, 25 Nov 2014 00:04:04 +0530 > This patch switches to flex array to implement the flow caches, it brings > several advantages: > > - Reduce the size of the tun_struct structure, which allows us to increase the > upper limit of queues in future. > - Avoid higher order memory allocation. It will be useful when switching to > pure hashing in flow cache which may demand a larger size array in future. > > After this patch, the size of tun_struct on x86_64 reduced from 8512 to > 328 > > Signed-off-by: Jason Wang > Signed-off-by: Pankaj Gupta > Reviewed-by: David Gibson I see no reason to use flex arrays for this, you are preallocaing the memory so if anything flex array is adding an unnecessary level of redirection for every access in return for no real gains. Just allocate the thing normally using kzalloc() or whatever. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/