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From: Junio C Hamano <gitster@pobox.com>
To: Jeff King <peff@peff.net>
Cc: git@vger.kernel.org
Subject: Re: diffcore-rename performance mode
Date: Tue, 18 Sep 2007 02:17:01 -0700	[thread overview]
Message-ID: <7v8x74wcxe.fsf@gitster.siamese.dyndns.org> (raw)
In-Reply-To: <20070918090105.GA11854@coredump.intra.peff.net> (Jeff King's message of "Tue, 18 Sep 2007 05:01:05 -0400")

Jeff King <peff@peff.net> writes:

> On Tue, Sep 18, 2007 at 01:58:17AM -0700, Junio C Hamano wrote:
>
>> > I thought we were holding counts of hashes, in which case there _is_ no
>> > overflow.
>> 
>> The raw hashval (the fingerprint recorded in struct spanhash) is
>> further reduced and used as an index into spahash_top.data[].
>> So more than one hashval can try to sit in the same slot in
>> spanhash_top.data[] array.
>
> Right, that's sort of what I was hinting at in the original message. Can
> we just make the hash table big enough to use the fingerprint hashes
> directly? It's going to use a bit more memory, but lookups should be
> very fast. I'll try to experiment and get some numbers.

Thanks -- I vaguely recall large hash was disastrous for me
(trashed cache), but that was on a different hardware, different
time.

  reply	other threads:[~2007-09-18  9:17 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-09-18  8:23 diffcore-rename performance mode Jeff King
2007-09-18  8:49 ` Junio C Hamano
2007-09-18  8:54   ` Jeff King
2007-09-18  8:58     ` Junio C Hamano
2007-09-18  9:01       ` Jeff King
2007-09-18  9:17         ` Junio C Hamano [this message]
2007-09-18 11:20     ` Johannes Schindelin
2007-09-25 16:38     ` Jeff King
2007-09-25 19:06       ` Jeff King
2007-09-25 19:10         ` Andreas Ericsson
2007-09-25 19:32         ` David Kastrup
2007-09-25 19:52           ` Jeff King
2007-09-18 22:12 ` Linus Torvalds

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