From mboxrd@z Thu Jan  1 00:00:00 1970
From: Jeff King <peff@peff.net>
Subject: Re: [PATCH] Preallocate hash tables when the number of inserts are
 known in advance
Date: Sun, 17 Mar 2013 04:51:07 -0400
Message-ID: <20130317085107.GB934@sigill.intra.peff.net>
References: <1363490886-29729-1-git-send-email-pclouds@gmail.com>
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Cc: git@vger.kernel.org, Junio C Hamano <gitster@pobox.com>
To: =?utf-8?B?Tmd1eeG7hW4gVGjDoWkgTmfhu41j?= Duy <pclouds@gmail.com>
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On Sun, Mar 17, 2013 at 10:28:06AM +0700, Nguyen Thai Ngoc Duy wrote:

> This avoids unnecessary re-allocations and reinsertions. On webkit.git
> (i.e. about 182k inserts to the name hash table), this reduces about
> 100ms out of 3s user time.

Good idea.

I had a similar thought when analyzing the hashing behavior of
pack-objects' "Counting objects..." phase, but it had even less impact
there. The insertions are just drowned out by the number of lookups in
that case.

-Peff