From: Nguyen Thai Ngoc Duy <pclouds@gmail.com>
To: Dave Zarzycki <zarzycki@apple.com>
Cc: git@vger.kernel.org, Thomas Rast <trast@inf.ethz.ch>,
Joshua Redstone <joshua.redstone@fb.com>
Subject: Re: [PATCH 6/6] Automatically switch to crc32 checksum for index when it's too large
Date: Mon, 6 Feb 2012 15:54:37 +0700 [thread overview]
Message-ID: <CACsJy8Dv9fUzL3COZKVw_KR6aF20kHaw8M4CdBXJDA9H3fbxLw@mail.gmail.com> (raw)
In-Reply-To: <E799595D-61B3-4978-BCE1-BA6A33034B55@apple.com>
2012/2/6 Dave Zarzycki <zarzycki@apple.com>:
> Which crc32 polynomial is being used? crc32c (a.k.a. Castagnoli)? It would be great if this were the same polynomial that Intel implements in hardware via SSE4.2.
It's zlib's crc32.
> On Feb 5, 2012, at 9:48 PM, Nguyễn Thái Ngọc Duy <pclouds@gmail.com> wrote:
>
>> An experiment with -O3 is done on Intel D510@1.66GHz. At around 250k
>> entries, index reading time exceeds 0.5s. Switching to crc32 brings it
>> back lower than 0.2s.
>>
>> On 4M files index, reading time with SHA-1 takes ~8.4, crc32 2.8s.
--
Duy
next prev parent reply other threads:[~2012-02-06 8:55 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-02-06 5:48 [PATCH 1/6] read-cache: use sha1file for sha1 calculation Nguyễn Thái Ngọc Duy
2012-02-06 5:48 ` [PATCH 2/6] csum-file: make sha1 calculation optional Nguyễn Thái Ngọc Duy
2012-02-06 5:48 ` [PATCH 3/6] Stop producing index version 2 Nguyễn Thái Ngọc Duy
2012-02-06 7:10 ` Junio C Hamano
2012-02-07 3:09 ` Shawn Pearce
2012-02-07 4:50 ` Nguyen Thai Ngoc Duy
2012-02-07 8:51 ` Nguyen Thai Ngoc Duy
2012-02-07 5:21 ` Junio C Hamano
2012-02-07 17:25 ` Thomas Rast
2012-02-06 5:48 ` [PATCH 4/6] Introduce index version 4 with global flags Nguyễn Thái Ngọc Duy
2012-02-06 5:48 ` [PATCH 5/6] Allow to use crc32 as a lighter checksum on index Nguyễn Thái Ngọc Duy
2012-02-07 3:17 ` Shawn Pearce
2012-02-07 4:04 ` Dave Zarzycki
2012-02-07 4:29 ` Dave Zarzycki
2012-02-06 5:48 ` [PATCH 6/6] Automatically switch to crc32 checksum for index when it's too large Nguyễn Thái Ngọc Duy
2012-02-06 8:50 ` Dave Zarzycki
2012-02-06 8:54 ` Nguyen Thai Ngoc Duy [this message]
2012-02-06 9:07 ` Dave Zarzycki
2012-02-06 7:34 ` [PATCH 1/6] read-cache: use sha1file for sha1 calculation Junio C Hamano
2012-02-06 8:36 ` Nguyen Thai Ngoc Duy
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