From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id F075DC433EF for ; Tue, 12 Oct 2021 19:16:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D23D161074 for ; Tue, 12 Oct 2021 19:16:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233467AbhJLTSE (ORCPT ); Tue, 12 Oct 2021 15:18:04 -0400 Received: from pb-smtp20.pobox.com ([173.228.157.52]:62636 "EHLO pb-smtp20.pobox.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232502AbhJLTSE (ORCPT ); Tue, 12 Oct 2021 15:18:04 -0400 Received: from pb-smtp20.pobox.com (unknown [127.0.0.1]) by pb-smtp20.pobox.com (Postfix) with ESMTP id F16A314B249; Tue, 12 Oct 2021 15:16:01 -0400 (EDT) (envelope-from junio@pobox.com) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed; d=pobox.com; h=from:to:cc :subject:references:date:message-id:mime-version:content-type; s=sasl; bh=4xl7mnYjlgGBI1a9bDGjuKL/ha+VtubcvkH/GMCah/A=; b=BWnp 53HneV2C6P+NTUVSOJ5PVYaDa7f2L+QkSIMYfsrz1YPyJlhpFEa8pjFKJgD/7h+4 RzelsJOH1OGeUwuaDp1anPBOyz1ZgO/9uEc2D5w6w0N+dJYN5bSkIl2aXxld7db0 AkJtpZeOpW2PwYe9ILG/PYr2SZCCf4YsC+Zl74Y= Received: from pb-smtp20.sea.icgroup.com (unknown [127.0.0.1]) by pb-smtp20.pobox.com (Postfix) with ESMTP id E9E6314B248; Tue, 12 Oct 2021 15:16:01 -0400 (EDT) (envelope-from junio@pobox.com) Received: from pobox.com (unknown [104.133.2.91]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by pb-smtp20.pobox.com (Postfix) with ESMTPSA id 6BB9114B246; Tue, 12 Oct 2021 15:15:59 -0400 (EDT) (envelope-from junio@pobox.com) From: Junio C Hamano To: Phillip Wood Cc: Victoria Dye , phillip.wood@dunelm.org.uk, Victoria Dye via GitGitGadget , git@vger.kernel.org, stolee@gmail.com, newren@gmail.com, Taylor Blau , Bagas Sanjaya , =?utf-8?B?w4Z2YXIgQXJuZmrDtnI=?= =?utf-8?B?w7A=?= Bjarmason Subject: Re: [PATCH v3 6/8] reset: make sparse-aware (except --mixed) References: <330e0c0977480d0506801854fcaa6c9f2b014569.1633641339.git.gitgitgadget@gmail.com> <52768318-ef8a-b26f-d4bc-d5c91779ccdb@github.com> <47d4c810-0b56-45b0-944c-72c4d047f9b6@gmail.com> Date: Tue, 12 Oct 2021 12:15:58 -0700 Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.2 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-Pobox-Relay-ID: D53F049C-2B90-11EC-80BF-F327CE9DA9D6-77302942!pb-smtp20.pobox.com Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org Phillip Wood writes: > I haven't really thought this through but could we teach > unpack_trees() to call prime_cache_tree() rather than > cache_tree_update() when that would be safe? For callers that use > oneway_merge() merge it should always be safe I think and it might be > possible to modify twoway_merge() to signal if the final tree in the > index matches the second one passed to it. We could have a more > general mechanism for the callback to signal if it is safe to prime > the tree but I suspect the callers that are using custom callbacks are > not updating the whole tree. Before going in any direction, other than doing nothing ;-), we'd need to see how expensive "prime" and "update" are. Having said that. * Your idea is quite beneficial for callers of unpack_trees() as they no longer have to decide whether they want to make a separate call to "prime". * Right now we do not seem to have a codepath that (1) populates the index entries from existing trees (not necessarily making the index in complete sync with the trees) without unpack_trees() and (2) does "prime" to fix the cache tree but such a codepath may want to do either "prime" or "update", or neither. When it knows that it damages cache-tree so badly, and that it is often expected that the user would make many other changes to the index before writing it out as a tree, it may choose not to do either. Thanks.