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([2605:a601:9b88:8300:4178:7958:947f:ef4f]) by smtp.gmail.com with ESMTPSA id af79cd13be357-914f870c37dsm847436385a.19.2026.05.28.08.28.55 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 28 May 2026 08:28:55 -0700 (PDT) Message-ID: Date: Thu, 28 May 2026 11:28:55 -0400 Precedence: bulk X-Mailing-List: git@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 0/3] pack-objects: support bitmaps and delta-islands with `--path-walk` To: Taylor Blau , git@vger.kernel.org Cc: Junio C Hamano , Jeff King , Elijah Newren References: Content-Language: en-US From: Derrick Stolee In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 5/27/26 7:18 PM, Taylor Blau wrote: > Here is a trimmed-down reroll of my series to make `--path-walk` work > with reachability bitmaps and delta-islands. This series was originally > an RFC that was a companion to Stolee's recent patches to extend > `--filter` support to `--path-walk` [1]. > > Since the previous round, Stolee's series has graduated and incorporated > the filter-related patches from my earlier RFC [2]. What remains are the > three patches here that implement support for reachability bitmaps and > delta-islands under `--path-walk`. > > * The first patch allows `--path-walk` to use reachability bitmaps when > they can answer the request, falling back to path-walk enumeration > when they cannot. It also lets bitmap writing see the same commit > candidates that the regular traversal would have shown to the bitmap > selector. > > * The second patch is preparatory, and factors the > delta-islands-specific tree-depth recording from `show_object()` into > a helper. > > * The final patch teaches the path-walk callback to perform the same > delta-islands side effects as the regular traversal: propagating > island marks for commits, and recording tree depths for trees. This > gives `resolve_tree_islands()` the same input in either enumeration > mode, so the existing island checks can be reused unchanged. I've applied these patches locally and confirmed that each one passes the test suite with GIT_TEST_PACK_PATH_WALK=1, which helps to confirm that the changes are correct (all existing bitmap tests create and use the bitmaps with --path-walk unless explicitly disabled). Should we add GIT_TEST_PACK_PATH_WALK=1 to the test-var CI build, now that this is going to be more commonly used? Do you have any end-to-end performance data to demonstrate that these changes are effective at scale? Are we still producing packfiles with the pack-file compression and now with .bitmap files? How does this impact the performance of a clone or fetch when using a bitmap index at read time? With that in mind, should we update any t/perf/ test to cover some of these scenarios? I'm running a few with GIT_TEST_PACK_PATH_WALK=1 on my laptop as a test, but it's taking a while. If you have stats ready from your local testing, then that would be interesting. Thanks, -Stolee