From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeff King Subject: Re: diffcore-rename performance mode Date: Tue, 18 Sep 2007 05:01:05 -0400 Message-ID: <20070918090105.GA11854@coredump.intra.peff.net> References: <20070918082321.GA9883@coredump.intra.peff.net> <7vsl5cwe6p.fsf@gitster.siamese.dyndns.org> <20070918085413.GA11751@coredump.intra.peff.net> <7vhclswdsm.fsf@gitster.siamese.dyndns.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: git@vger.kernel.org To: Junio C Hamano X-From: git-owner@vger.kernel.org Tue Sep 18 11:01:18 2007 Return-path: Envelope-to: gcvg-git-2@gmane.org Received: from vger.kernel.org ([209.132.176.167]) by lo.gmane.org with esmtp (Exim 4.50) id 1IXYxJ-0003lY-Gr for gcvg-git-2@gmane.org; Tue, 18 Sep 2007 11:01:18 +0200 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752796AbXIRJBK (ORCPT ); Tue, 18 Sep 2007 05:01:10 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752401AbXIRJBJ (ORCPT ); Tue, 18 Sep 2007 05:01:09 -0400 Received: from 66-23-211-5.clients.speedfactory.net ([66.23.211.5]:3445 "EHLO peff.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752067AbXIRJBI (ORCPT ); Tue, 18 Sep 2007 05:01:08 -0400 Received: (qmail 26263 invoked by uid 111); 18 Sep 2007 09:01:06 -0000 Received: from coredump.intra.peff.net (HELO coredump.intra.peff.net) (10.0.0.2) by peff.net (qpsmtpd/0.32) with SMTP; Tue, 18 Sep 2007 05:01:06 -0400 Received: by coredump.intra.peff.net (sSMTP sendmail emulation); Tue, 18 Sep 2007 05:01:05 -0400 Content-Disposition: inline In-Reply-To: <7vhclswdsm.fsf@gitster.siamese.dyndns.org> Sender: git-owner@vger.kernel.org Precedence: bulk X-Mailing-List: git@vger.kernel.org Archived-At: On Tue, Sep 18, 2007 at 01:58:17AM -0700, Junio C Hamano wrote: > > I thought we were holding counts of hashes, in which case there _is_ no > > overflow. > > The raw hashval (the fingerprint recorded in struct spanhash) is > further reduced and used as an index into spahash_top.data[]. > So more than one hashval can try to sit in the same slot in > spanhash_top.data[] array. Right, that's sort of what I was hinting at in the original message. Can we just make the hash table big enough to use the fingerprint hashes directly? It's going to use a bit more memory, but lookups should be very fast. I'll try to experiment and get some numbers. -Peff