Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753888AbaFPGkN (ORCPT ); Mon, 16 Jun 2014 02:40:13 -0400 Received: from 216-12-86-13.cv.mvl.ntelos.net ([216.12.86.13]:57791 "EHLO brightrain.aerifal.cx" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753666AbaFPGkM (ORCPT ); Mon, 16 Jun 2014 02:40:12 -0400 Date: Mon, 16 Jun 2014 02:39:08 -0400 From: Rich Felker To: Andy Lutomirski Cc: "H. Peter Anvin" , Mikael Pettersson , Russ Cox , Linux API , Ian Taylor , "linux-kernel@vger.kernel.org" , X86 ML Subject: Re: [RFC 0/2] __vdso_findsym Message-ID: <20140616063907.GX179@brightrain.aerifal.cx> References: <21405.44257.742122.786960@gargle.gargle.HOWL> <20140615143500.GP179@brightrain.aerifal.cx> <539DD26B.3060709@zytor.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Jun 15, 2014 at 11:22:48AM -0700, Andy Lutomirski wrote: > >>[1] The only comprehensible description of the GNU hash extension that > >>I could find is on Oracle's blog (!) > >> > > > > Curious about this blog. We do have a GNU hash implementation in Syslinux, too, for another reference. > > > > https://blogs.oracle.com/ali/entry/gnu_hash_elf_sections > > FWIW, I bet that __vdso_findsym could be smaller if it used the GNU > hash. Maybe it would save about the same amount of space that turning > on the GNU hash would take up. How so? My implementation of gnu hash lookup in musl's dynamic linker is somewhat larger than the sysv hash lookup, and that's even with skipping the bloom filter (which did not seem to yield any benefit, though we may revisit this issue later). The actual hash function is _slightly_ smaller for gnu, but the lookup function has a lot more work to do. Of course for the size of vdso's symbol table, a pure linear search with no hash table would suffice... Rich -- 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/