Openwall GNU/*/Linux - a small security-enhanced Linux distro for servers
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date: Mon, 14 Sep 2015 07:47:37 +0530
From: Sayantan Datta <std2048@...il.com>
To: john-dev <john-dev@...ts.openwall.com>
Subject: Re: bt.c initial table size

On Sun, Sep 13, 2015 at 1:55 AM, Solar Designer <solar@...nwall.com> wrote:

> Sayantan -
>
> When testing with lots of hashes, I was getting many "Progress is too
> slow!! trying next table size." and this hurt the speeds badly (2 to 3.5
> minutes total running time for my test).  To have bt.c use a larger
> table size right away, I hacked this into create_perfect_hash_table(),
> right before the "do { ... } while(1);" loop:
>
>         for (i = 0; i < 9; i++) {
>                 unsigned int temp;
>                 temp = next_prime(approx_offset_table_sz % 10);
>                 approx_offset_table_sz /= 10;
>                 approx_offset_table_sz *= 10;
>                 approx_offset_table_sz += temp;
>
>                 i++;
>
>                 if (!(i % 5)) {
>                         multiplier_ot += inc_ot;
>                         multiplier_ht += inc_ht;
>                         approx_offset_table_sz = (((long
> double)num_loaded_hashes / 4.0) * multiplier_ot + 10.00);
>                         approx_hash_table_sz = ((long
> double)num_loaded_hashes * multiplier_ht);
>                 }
>         }
>
> The loop contents is some lines I copied from your larger loop.  Oh, I
> just noticed I got an extra "i++" in there.  Well, I am writing this to
> ask you to make something like this a standard feature, where we could
> request a larger initial table size without hacking the source code -
> and maybe the default needs to be bumped up too?
>
> Alexander
>

Hi Solar,

How would you like to request the table size - the exact table size or a
multiplier(as in table size = num_loaded_hashes * multiplier + prime) .
Also, if you request a larger table size, you are not guaranteed that it
will 'build the tables on first try', however, the probability of that
happening is definitely higher.

Regards,
Sayantan

[ CONTENT OF TYPE text/html SKIPPED ]

Powered by blists - more mailing lists

Your e-mail address:

Powered by Openwall GNU/*/Linux - Powered by OpenVZ