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From: Junio C Hamano <gitster@pobox.com>
To: Takuto Ikuta <tikuta@chromium.org>
Cc: git@vger.kernel.org, Jonathan Tan <jonathantanmy@google.com>
Subject: Re: [PATCH] fetch-pack.c: use oidset to check existence of loose object
Date: Fri, 09 Mar 2018 11:41:36 -0800	[thread overview]
Message-ID: <xmqqa7vh595b.fsf@gitster-ct.c.googlers.com> (raw)
In-Reply-To: <xmqqd10d6ser.fsf@gitster-ct.c.googlers.com> (Junio C. Hamano's message of "Fri, 09 Mar 2018 10:00:12 -0800")

Junio C Hamano <gitster@pobox.com> writes:

>> Yes. But I think the default limit for the number of loose objects, 7000,
>> gives us small overhead when we do enumeration of all objects.
>
> Hmph, I didn't see the code that does the estimation of loose object
> count before starting to enumerate, though.

Another thing the code could do to avoid negative consequences on
projects that look quite different from yours (e.g. the other side
does not have insane number of refs, but there are locally quite a
few loose objects) is to count how many entries are on *refs list
before we decide to enumerate all loose objects.  When the refs list
is relatively shorter than the estimated number of loose objects
(you can actually do the estimation based on sampling, or just rely
on your assumed 7k), it may be a win _not_ to trigger the new code
you are adding to this codepath with this patch.  I would imagine
that the simplest implementaion may just count 

	for (ref = *refs, count = 0; ref && count++ < LIMIT; ref = ref->next)
		;
	use_oidset_optim = (LIMIT <= count);
		
assuming your "up to 7k loose objects" and then experimenting to
determine the LIMIT which is a rough number of refs that makes the
oidset optimization worthwhile.

We need a bit better/descriptive name for the LIMIT, if we go that
route, though.

Thanks.


 

  reply	other threads:[~2018-03-09 19:41 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-03-08 12:06 [PATCH] fetch-pack.c: use oidset to check existence of loose object Takuto Ikuta
2018-03-08 17:19 ` René Scharfe
2018-03-09 13:42   ` Takuto Ikuta
2018-03-08 18:42 ` Junio C Hamano
2018-03-09 13:11   ` [PATCH v2 0/1] " Takuto Ikuta
2018-03-09 13:11     ` [PATCH v2 1/1] " Takuto Ikuta
2018-03-09 13:26       ` [PATCH v3] " Takuto Ikuta
2018-03-09 19:54         ` Junio C Hamano
2018-03-10 13:19           ` Takuto Ikuta
2018-03-13 17:53             ` Junio C Hamano
2018-03-14  6:26               ` Takuto Ikuta
2018-03-10 12:34         ` [PATCH v4] " Takuto Ikuta
2018-03-10 12:46           ` [PATCH v5] " Takuto Ikuta
2018-03-13 19:04             ` Junio C Hamano
2018-03-14  6:05           ` [PATCH v6] " Takuto Ikuta
2018-03-14  6:32             ` [PATCH v7] " Takuto Ikuta
2018-03-09 14:12   ` [PATCH] " Takuto Ikuta
2018-03-09 18:00     ` Junio C Hamano
2018-03-09 19:41       ` Junio C Hamano [this message]
2018-03-13 15:30   ` [PATCH] sha1_file: restore OBJECT_INFO_QUICK functionality Jonathan Tan

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