From: Duy Nguyen <pclouds@gmail.com>
Date: Thu, 25 Apr 2013 21:12:10 GMT
Subject: Re: [PATCH] Hold an 'unsigned long' chunk of the sha1 in obj_hash
Message-ID: <CACsJy8CJO+rLHgMo+F_fsWBj7Nm0rbpVNHTLXbi7u60+rT0OJQ@mail.gmail.com>
In-Reply-To: <6c2b67a2f0b67ee796c7676e3febe4c61ab85d4a.1366912627.git.trast@inf.ethz.ch>

On Fri, Apr 26, 2013 at 1:04 AM, Thomas Rast <trast@inf.ethz.ch> wrote:
> So we take a slightly different approach, and trade some memory for
> better cache locality.  Namely, we change the hash table slots to
> contain
>
>   struct object *obj;
>   unsigned long sha1prefix;
>
> We use this new 'sha1prefix' field to store the first part of the
> object's sha1, from which its hash table slot is computed.

Clever. I went a similar road before. But I put the whole 20-byte
sha-1 in obj_hash, which makes obj_hash even bigger and less
cache-friendly.
--
Duy