From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vlad Yasevich Subject: Re: [PATCH net-next 4/9] net: sctp: sctp_outq: consolidate chars into bitfield Date: Wed, 17 Apr 2013 11:35:49 -0400 Message-ID: <516EC155.5060202@gmail.com> References: <1366146438-8815-1-git-send-email-dborkman@redhat.com> <1366146438-8815-5-git-send-email-dborkman@redhat.com> <516E6ABD.2040904@redhat.com> <20130417152757.GD5149@hmsreliant.think-freely.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Daniel Borkmann , David Laight , davem@davemloft.net, netdev@vger.kernel.org, linux-sctp@vger.kernel.org To: Neil Horman Return-path: Received: from mail-qc0-f182.google.com ([209.85.216.182]:56679 "EHLO mail-qc0-f182.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S966772Ab3DQPfx (ORCPT ); Wed, 17 Apr 2013 11:35:53 -0400 In-Reply-To: <20130417152757.GD5149@hmsreliant.think-freely.org> Sender: netdev-owner@vger.kernel.org List-ID: On 04/17/2013 11:27 AM, Neil Horman wrote: > On Wed, Apr 17, 2013 at 11:26:21AM +0200, Daniel Borkmann wrote: >> On 04/17/2013 10:43 AM, David Laight wrote: >>>> __u32 outstanding_bytes; >>>> >>>> - /* Are we doing fast-rtx on this queue */ >>>> - char fast_rtx; >>>> - >>>> - /* Corked? */ >>>> - char cork; >>>> - >>>> - /* Is this structure empty? */ >>>> - char empty; >>>> + __u8 fast_rtx:1, /* Are we doing fast-rtx on this queue */ >>>> + cork:1, /* Corked? */ >>>> + empty:1; /* Is this structure empty? */ >>>> }; >>> >>> Use of bitfields just makes the code slower. >>> The only real excuse for using them is to reduce the size >>> of a structure that is allocated a lot. >> >> sctp_outq is _embedded_ into an sctp_association structure, which >> has [size: 2280, cachelines: 36, members: 76]! A next step would be >> to try to reorder its elements carefully and see if we can reduce >> the size by filling some holes. > Unrelated note: How did you get pahole to give you that information? For some > reason pahole can never glean any useful information about struct > sctp_association for me, despite having dwarf info embedded into the cu. > pahole -C sctp_association works for me. -vlad > Neil > >> -- >> To unsubscribe from this list: send the line "unsubscribe linux-sctp" in >> the body of a message to majordomo@vger.kernel.org >> More majordomo info at http://vger.kernel.org/majordomo-info.html >> > -- > To unsubscribe from this list: send the line "unsubscribe linux-sctp" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html >