Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Thu, 14 Nov 2002 21:35:03 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Thu, 14 Nov 2002 21:35:03 -0500 Received: from packet.digeo.com ([12.110.80.53]:30956 "EHLO packet.digeo.com") by vger.kernel.org with ESMTP id ; Thu, 14 Nov 2002 21:35:03 -0500 Message-ID: <3DD45EEB.4E4F170@digeo.com> Date: Thu, 14 Nov 2002 18:41:47 -0800 From: Andrew Morton X-Mailer: Mozilla 4.79 [en] (X11; U; Linux 2.5.46 i686) X-Accept-Language: en MIME-Version: 1.0 To: Tim Hockin CC: Tim Hockin , Linux Kernel Mailing List Subject: Re: [BK PATCH 1/2] Remove NGROUPS hardlimit (resend w/o qsort) References: <3DD44E39.4703C2DA@digeo.com> from "Andrew Morton" at Nov 14, 2002 05:30:33 PM <200211150233.gAF2XQv15588@www.hockin.org> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-OriginalArrivalTime: 15 Nov 2002 02:41:51.0454 (UTC) FILETIME=[8D3B47E0:01C28C50] Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 807 Lines: 22 Tim Hockin wrote: > > > 10,000 bits isn't much. Maybe: > > That's 10000 USED bits. Remember groups are non-contiguously allocated. If > a task is a member of just groups 32767 and 65535, you'll get one bit per > page used, and when they call getgroups() you need to pull it apart and > return an array of gid_t. > Well that's what I was asking. What is the maximum group ID? 0xffffffff? In that case a radix tree _might_ suit. All you need to put in the node is a (void *)1 or (void *)0. But it won't be very space-efficient for really sparse groups. - 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/