From mboxrd@z Thu Jan 1 00:00:00 1970 From: Junio C Hamano Subject: Re: diffcore-rename performance mode Date: Tue, 18 Sep 2007 02:17:01 -0700 Message-ID: <7v8x74wcxe.fsf@gitster.siamese.dyndns.org> 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> <20070918090105.GA11854@coredump.intra.peff.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: git@vger.kernel.org To: Jeff King X-From: git-owner@vger.kernel.org Tue Sep 18 11:17:29 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 1IXZCw-00009o-Ka for gcvg-git-2@gmane.org; Tue, 18 Sep 2007 11:17:27 +0200 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754417AbXIRJRL (ORCPT ); Tue, 18 Sep 2007 05:17:11 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754403AbXIRJRK (ORCPT ); Tue, 18 Sep 2007 05:17:10 -0400 Received: from rune.sasl.smtp.pobox.com ([208.210.124.37]:51471 "EHLO sasl.smtp.pobox.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753906AbXIRJRJ (ORCPT ); Tue, 18 Sep 2007 05:17:09 -0400 Received: from pobox.com (ip68-225-240-77.oc.oc.cox.net [68.225.240.77]) (using TLSv1 with cipher AES128-SHA (128/128 bits)) (No client certificate requested) by rune.sasl.smtp.pobox.com (Postfix) with ESMTP id 34F271373D5; Tue, 18 Sep 2007 05:17:25 -0400 (EDT) In-Reply-To: <20070918090105.GA11854@coredump.intra.peff.net> (Jeff King's message of "Tue, 18 Sep 2007 05:01:05 -0400") User-Agent: Gnus/5.110006 (No Gnus v0.6) Emacs/21.4 (gnu/linux) Sender: git-owner@vger.kernel.org Precedence: bulk X-Mailing-List: git@vger.kernel.org Archived-At: Jeff King writes: > 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. Thanks -- I vaguely recall large hash was disastrous for me (trashed cache), but that was on a different hardware, different time.