From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on dcvr.yhbt.net X-Spam-Level: X-Spam-ASN: AS31976 209.132.180.0/23 X-Spam-Status: No, score=-4.2 required=3.0 tests=AWL,BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,RCVD_IN_DNSWL_HI, RP_MATCHES_RCVD shortcircuit=no autolearn=ham autolearn_force=no version=3.4.0 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by dcvr.yhbt.net (Postfix) with ESMTP id 5613620958 for ; Thu, 23 Mar 2017 19:02:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932743AbdCWTCS (ORCPT ); Thu, 23 Mar 2017 15:02:18 -0400 Received: from pb-smtp1.pobox.com ([64.147.108.70]:58407 "EHLO sasl.smtp.pobox.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S932166AbdCWTCR (ORCPT ); Thu, 23 Mar 2017 15:02:17 -0400 Received: from sasl.smtp.pobox.com (unknown [127.0.0.1]) by pb-smtp1.pobox.com (Postfix) with ESMTP id C55A665089; Thu, 23 Mar 2017 15:02:15 -0400 (EDT) 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=JIRF1pzK6DykiCMConS0utdWbys=; b=VIEnbU dA4pfJfgXO3ejX5gQlPWsA8sHwpYfV3Mhf60nz8Tx86+uJWOoNfGmAXZyTjqSlwN sZ8RjtVYpIFZFzlM5ZK5tcKF0ozAs2HEDISp6DuX+FxugKt09HWGZYMYOcU1rVE4 bEWi0X4JgI2wVj7ZfEvcgvX7vIR2XR7LHXYsM= 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=yUpJt+eebOHuiRaxFHgue6XfNNei3Cwy +N+UR608uf+Kmx66xUoelo1/vVxcQfut3DKS0LZPZ/wh4NzgaJd4l6wlKLN1f2Et lphRMg05Q8bvrBXVJN+itjOxafO22b5t4+VuirvfH5m0XrrpZbk5okam29MTxfRI Bkr8iXR1p4k= Received: from pb-smtp1.nyi.icgroup.com (unknown [127.0.0.1]) by pb-smtp1.pobox.com (Postfix) with ESMTP id BDF1765088; Thu, 23 Mar 2017 15:02:15 -0400 (EDT) Received: from pobox.com (unknown [104.132.0.95]) (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 21A0765087; Thu, 23 Mar 2017 15:02:15 -0400 (EDT) From: Junio C Hamano To: Jeff King Cc: Linus Torvalds , Johannes Schindelin , Jonathan Nieder , Lars Schneider , Git Mailing List Subject: Re: USE_SHA1DC is broken in pu References: <2B1DE627-11C8-4FA5-A354-76B6C475666A@gmail.com> <20170322220246.GD26108@aiede.mtv.corp.google.com> <20170323174750.xyucxmfhuc6dbrzc@sigill.intra.peff.net> Date: Thu, 23 Mar 2017 12:02:14 -0700 In-Reply-To: <20170323174750.xyucxmfhuc6dbrzc@sigill.intra.peff.net> (Jeff King's message of "Thu, 23 Mar 2017 13:47:50 -0400") Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/25.1.91 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-Pobox-Relay-ID: 3A964B90-0FFB-11E7-BCDA-97B1B46B9B0B-77302942!pb-smtp1.pobox.com Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org Jeff King writes: > Side note: I also have a feeling that any operation that cares about > non-object sha1 performance is probably ripe for other, bigger > optimizations. If you update 300MB worth of index entries, then the > cost of computing a checksum over it isn't a big deal. But if you have > a 300MB index file and you update one entry (or you just want to read > one entry), maybe we ought to consider solutions that don't involve > the whole 300MB in the first place. I know that's a much harder change > because it may involve new on-disk formats. But it seems like that's > the right long-term path forward. Yes ;-)