From mboxrd@z Thu Jan 1 00:00:00 1970 From: Junio C Hamano Subject: Re: [PATCH v2 2/2] index-pack: kill union delta_base to save memory Date: Sat, 28 Feb 2015 18:37:40 -0800 Message-ID: References: <1424397488-22169-1-git-send-email-pclouds@gmail.com> <1424947928-19396-1-git-send-email-pclouds@gmail.com> <1424947928-19396-3-git-send-email-pclouds@gmail.com> Mime-Version: 1.0 Content-Type: text/plain Cc: Git Mailing List , matthew sporleder To: Duy Nguyen X-From: git-owner@vger.kernel.org Sun Mar 01 03:37:53 2015 Return-path: Envelope-to: gcvg-git-2@plane.gmane.org Received: from vger.kernel.org ([209.132.180.67]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1YRtlR-0000Kq-9p for gcvg-git-2@plane.gmane.org; Sun, 01 Mar 2015 03:37:53 +0100 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752933AbbCACht (ORCPT ); Sat, 28 Feb 2015 21:37:49 -0500 Received: from pb-smtp1.int.icgroup.com ([208.72.237.35]:55642 "EHLO sasl.smtp.pobox.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752605AbbCAChs (ORCPT ); Sat, 28 Feb 2015 21:37:48 -0500 Received: from sasl.smtp.pobox.com (unknown [127.0.0.1]) by pb-smtp1.pobox.com (Postfix) with ESMTP id E6ED73BF76; Sat, 28 Feb 2015 21:37:41 -0500 (EST) DKIM-Signature: v=1; a=rsa-sha1; c=relaxed; d=pobox.com; h=from:to:cc :subject:references:date:in-reply-to:message-id:mime-version :content-type; s=sasl; bh=DJJhuPsPCxABrqlQGnsWXBlWXmg=; b=tsNr6w 38gPPF1BJXv+7Oj6owfGqBSkKN1vMoaNLN1OKqfS8yrdOr4I6WTM9DrGvZhTbNb8 ctrKJph+Q8EW0PT23YuplYqNzcn7OI1qm/mCFD2AGVzNdJ+MJGiEZa6mFKJWCadu GpEg7MVNsjIh5kZyBaNjmOewJ846OHaOOhWQE= DomainKey-Signature: a=rsa-sha1; c=nofws; d=pobox.com; h=from:to:cc :subject:references:date:in-reply-to:message-id:mime-version :content-type; q=dns; s=sasl; b=pwYYW1ax7g+7cji1rto3jXfafM/ahz78 /OTJCiIQSfXW/KgkxM0dwvWL7g2z0wCv6xM131wfFwsI9DH0d7tsCEdQa/5ZunKL etRVu5KcOVGGO7h2XqrUlnIMG7RTAdl1R+aOAlahTZ8wDrSjhY1+XRtXuKA6/PZh XJI/jOP/VAE= Received: from pb-smtp1.int.icgroup.com (unknown [127.0.0.1]) by pb-smtp1.pobox.com (Postfix) with ESMTP id DF2833BF75; Sat, 28 Feb 2015 21:37:41 -0500 (EST) Received: from pobox.com (unknown [72.14.226.9]) (using TLSv1.2 with cipher DHE-RSA-AES128-SHA (128/128 bits)) (No client certificate requested) by pb-smtp1.pobox.com (Postfix) with ESMTPSA id 6940F3BF74; Sat, 28 Feb 2015 21:37:41 -0500 (EST) In-Reply-To: (Duy Nguyen's message of "Sat, 28 Feb 2015 18:44:07 +0700") User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.3 (gnu/linux) X-Pobox-Relay-ID: EED15178-BFBB-11E4-A1F4-29999F42C9D4-77302942!pb-smtp1.pobox.com Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org Archived-At: Duy Nguyen writes: >> Probably "Not so ancient versions of Git tries to use ofs-delta >> encoding whenever possible, so it is expected that objects encoded >> using ref-delta are minority" may be closer to the truth. And that >> observation does justify why using two separate pools (one with >> 8-byte entries for ofs-delta, the other with 20-byte entries for >> ref-delta) is a better idean than using one pool with 20-byte >> entries for both kinds. > > Yes. Looks good. Should I send a patch, or you fix the commit > message locally? Thinking about the above again, I do not think there is any point saying "not so ancient versions of Git", as the receiving index-pack would not even know what implementaiton of Git sits on the other end of the connection; it may even be a jGit based server, for example. So something like: Because ofs-delta encoding is more efficient space-wise and more performant at runtime than ref-delta encoding, Git packers try to use ofs-delta whenever possible, and it is expected that objects encoded as ref-delta are minority. perhaps?