From: Karsten Blees <karsten.blees@gmail.com>
To: Fredrik Gustafsson <iveqy@iveqy.com>
Cc: Git List <git@vger.kernel.org>
Subject: Re: [PATCH v2 0/5] New hash table implementation
Date: Thu, 26 Sep 2013 15:55:52 +0200 [thread overview]
Message-ID: <52443CE8.6000902@gmail.com> (raw)
In-Reply-To: <20130926101648.GD6615@paksenarrion.iveqy.com>
Am 26.09.2013 12:16, schrieb Fredrik Gustafsson:
> On Tue, Sep 24, 2013 at 11:50:16AM +0200, Karsten Blees wrote:
>> Tests can be reproduced with 'time echo "perfhash[map] <method> 1000" | ./test-hashmap', see test-hashmap.c for definition of method flags.
>
> So I'm still curious about the actual performance improvements for git.
> I runned git describe on the linux kernel with both the old hashmap and
> this new one:
>
Performance was never the primary issue, the intention of the performance tests was to ensure that the new implementation doesn't *slow down* git.
>From the original PATCH/RFC:
- O(1) remove
- builtin entry chaining
- ready-to-use FNV-1 hash functions
- unit test
- additions are ~twice as fast
- uses less memory
So, the new implementation allows us to get rid of workarounds such as the CE_UNHASHED flag, duplicate entry chaining code and hash_name() implementations. It also addresses the memory usage FIXME in hash.h.
The simplified API may help prevent bugs such as the broken entry chaining in name-hash.c (see commits 2548183, 395c735, 2092678).
Maybe we can also replace some of the custom hash table implementations in attr.c, decorate.c, fast-import.c and object.c (to name just a few...).
prev parent reply other threads:[~2013-09-26 13:55 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-09-10 23:27 [PATCH/RFC 0/5] New hash table implementation Karsten Blees
2013-09-10 23:28 ` [PATCH/RFC 1/5] add a hashtable implementation that supports O(1) removal Karsten Blees
2013-09-11 23:56 ` Junio C Hamano
2013-09-23 9:16 ` Karsten Blees
2013-09-12 4:10 ` Junio C Hamano
2013-09-23 9:21 ` Karsten Blees
2013-09-10 23:28 ` [PATCH/RFC 2/5] buitin/describe.c: use new hash map implementation Karsten Blees
2013-09-10 23:29 ` [PATCH/RFC 3/5] diffcore-rename.c: move code around to prepare for the next patch Karsten Blees
2013-09-10 23:30 ` [PATCH/RFC 4/5] diffcore-rename.c: simplify finding exact renames Karsten Blees
2013-09-10 23:30 ` [PATCH/RFC 5/5] diffcore-rename.c: use new hash map implementation Karsten Blees
2013-09-24 9:50 ` [PATCH v2 0/5] New hash table implementation Karsten Blees
2013-09-24 9:51 ` [PATCH v2 1/5] add a hashtable implementation that supports O(1) removal Karsten Blees
2013-09-24 9:52 ` [PATCH v2 2/5] buitin/describe.c: use new hash map implementation Karsten Blees
2013-09-24 9:52 ` [PATCH v2 3/5] diffcore-rename.c: move code around to prepare for the next patch Karsten Blees
2013-09-24 9:53 ` [PATCH v2 4/5] diffcore-rename.c: simplify finding exact renames Karsten Blees
2013-09-24 9:54 ` [PATCH v2 5/5] diffcore-rename.c: use new hash map implementation Karsten Blees
2013-09-24 10:18 ` [PATCH v2 0/5] New hash table implementation Fredrik Gustafsson
2013-09-24 11:16 ` Tay Ray Chuan
2013-09-26 14:38 ` Karsten Blees
2013-09-26 10:16 ` Fredrik Gustafsson
2013-09-26 10:26 ` Duy Nguyen
2013-09-26 11:08 ` Fredrik Gustafsson
2013-09-26 11:14 ` Duy Nguyen
2013-09-26 13:55 ` Karsten Blees [this message]
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