From: Jeff King <peff@peff.net>
To: "Shawn O. Pearce" <spearce@spearce.org>
Cc: Junio C Hamano <gitster@pobox.com>, git@vger.kernel.org
Subject: Re: [PATCH 1/2] fetch-pack: Finish negotation if remote replies "ACK %s ready"
Date: Thu, 17 Mar 2011 03:15:12 -0400 [thread overview]
Message-ID: <20110317071512.GF11931@sigill.intra.peff.net> (raw)
In-Reply-To: <1300146519-26508-1-git-send-email-spearce@spearce.org>
On Mon, Mar 14, 2011 at 04:48:38PM -0700, Shawn O. Pearce wrote:
> Upon receiving "ACK %s ready" there is no point in looking at
> the remaining commits inside of rev_list. Sending additional
> "have %s" lines to the remote will not construct a smaller pack.
> It is unlikely a commit older than the current cut point will have
> a better delta base than the cut point itself has.
> [...]
> Assuming the client is only following the remote (and does not make
> its own local commits), the client needs 11 rounds to spin through
> the entire list of tags (32 commits per round, ceil(339/32) == 11).
> Unfortunately the server knows on the first "have %s" line that
> it can produce a good pack, and does not need to see the remaining
> 320 tags in the other 10 rounds.
Does this optimization help in that case? From looking at the code, it
seems that we offer "ACK %s ready" only in the case that the client
has something we do not. I.e., they _are_ building local commits on top.
> Over smart HTTP, the client must do an additional 10 HTTP POST
> requests, each of which incurs round-trip latency, and must upload
> the entire state vector of all known common objects. On the final
> POST request, this is 16 KiB worth of data.
This optimization aside, I wonder if it is worth bumping up the number
of haves we send in a chunk from 32 to something higher.
-Peff
next prev parent reply other threads:[~2011-03-17 7:15 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-03-14 23:48 [PATCH 1/2] fetch-pack: Finish negotation if remote replies "ACK %s ready" Shawn O. Pearce
2011-03-14 23:48 ` [PATCH 2/2] upload-pack: More aggressively send 'ACK %s ready' Shawn O. Pearce
2011-03-17 7:15 ` Jeff King [this message]
2011-03-17 7:16 ` [PATCH 1/2] fetch-pack: Finish negotation if remote replies "ACK %s ready" Jeff King
2011-03-17 15:51 ` Shawn Pearce
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