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From: Shawn Pearce <spearce@spearce.org>
To: git <git@vger.kernel.org>
Subject: expanding pack idx fanout table
Date: Mon, 8 Jul 2013 08:54:24 -0700
Message-ID: <CAJo=hJsto1ik=GTC8c3+2_jBuUqcAPL0UWp-1uoYYMpgbLB+qg@mail.gmail.com> (raw)

Has anyone studied the impact of converting the pack idx fanout table
from 256 entries to 65536 entries?

Back of the envelope estimates for 3.1M objects in linux.git suggests
a 2^16 fanout table would decrease the number of binary search
iterations from ~14 to ~6. The increased table costs an extra 255 KiB
of disk. On a 70M idx file this is noise.

I'm starting to wonder if increasing the fanout table once the object
count is above a certain threshold is a reasonable optimization for
larger repositories.

             reply index

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-07-08 15:54 Shawn Pearce [this message]
2013-07-08 17:37 ` Junio C Hamano
2013-07-08 17:58   ` Shawn Pearce
2013-07-09  4:19 ` Jeff King

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