Re: [PATCH 2/2] fetch: forgo full connectivity check if --filter

From: Junio C Hamano <gitster@pobox.com>
Date: Jan 30, 2020, 18:57 UTC
Message-ID: <xmqqimksdb6w.fsf@gitster-ct.c.googlers.com>
In-Reply-To: <20200129204326.GB17350@google.com>

Jonathan Nieder <jrnieder@gmail.com> writes:

Show 22 quoted lines

> Jonathan Tan wrote:
>
>> If a filter is specified, we do not need a full connectivity check on
>> the contents of the packfile we just fetched; we only need to check that
>> the objects referenced are promisor objects.
>>
>> This significantly speeds up fetches into repositories that have many
>> promisor objects, because during the connectivity check, all promisor
>> objects are enumerated (to mark them UNINTERESTING), and that takes a
>> significant amount of time.
>>
>> Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
>> ---
>> For example, a local fetch was sped up from 6.63s to 3.39s. The bulk of
>> the remaining time is spent in yet another connectivity check
>> (fetch_refs -> check_exist_and_connected) prior to the fetch - that will
>> hopefully be done in a subsequent patch.
>
> Can this information (at least the speedup) be included in the comment
> message?
>
> Or even better, can we demonstrate the impact using a perf test?

It does make sense, but let's queue these two first and then add it as a follow-up patch on top.

Thanks for writing and reviewing.