Follow @Openwall on Twitter for new release announcements and other news
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date: Fri, 18 Sep 2015 17:50:59 +0300
From: Solar Designer <>
Subject: Re: bitmap & hash table prefetching (was: Judy array)

magnum -

On Thu, Sep 17, 2015 at 07:09:30PM +0300, Solar Designer wrote:
> FWIW, the patch that I posted, which works best for me and which is
> now committed, prefetches only bitmap elements and then hash table
> elements for which the bitmap indicates a hit.  It does not prefetch
> "struct db_password *pw" (from which we're using the "binary" and
> "next_hash" fields), nor pw->binary (I mean the actual binary here,
> whereas the "binary" field is just a pointer).

The attached patch does that, and it assumes that "binary" itself is
allocated right after the tiny struct, so doesn't need to be prefetched
separately.  This should be suitable for commit now.

The 29M testcase:

real    0m40.821s
user    2m55.786s
sys     0m14.104s


View attachment "john-huge-prefetch2.diff" of type "text/plain" (5590 bytes)

Powered by blists - more mailing lists

Confused about mailing lists and their use? Read about mailing lists on Wikipedia and check out these guidelines on proper formatting of your messages.