linux-kernel - Re: [PATCH] low performance of lib/sort.c , kernel 2.6.18

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	29 Sep 2006 06:34:28 +0800
From:	Zou Nan hai <nanhai.zou@...el.com>
To:	Matt Mackall <mpm@...enic.com>
Cc:	keios <keios.cn@...il.com>, LKML <linux-kernel@...r.kernel.org>,
	Andrew Morton <akpm@...l.org>
Subject: Re: [PATCH] low performance of lib/sort.c , kernel 2.6.18

On Fri, 2006-09-29 at 06:33, Matt Mackall wrote:
> On Thu, Sep 28, 2006 at 11:18:45PM +0800, keios wrote:
> > It is a non-standard heap-sort algorithm implementation because the
> > index of child node is wrong . The sort function still outputs right
> > result, but the performance is O( n * ( log(n) + 1 ) ) , about 10% ~
> > 20% worse than standard algorithm .
> >
> > Signed-off-by: keios <keios.cn@...il.com>
> 
> Was a bit mystified by this as your patch matches what I've got
> in my userspace test harness from 2003.
> 
> Here's what I submitted, which is almost the same as yours:
> 
> http://www.kernel.org/pub/linux/kernel/people/akpm/patches/2.6/2.6.11-rc4/2.6.11-rc4-mm1/broken-out/lib-sort-heapsort-implementation-of-sort.patch
> 
> Then Zou Nan hai sent Andrew a fix for an off-by-one bug here (merged
> with my patch):
> 
> http://kernel.org/pub/linux/kernel/people/akpm/patches/2.6/2.6.11/2.6.11-mm1/broken-out/lib-sort-heapsort-implementation-of-sort.patch
> 
> ..which introduced the performance regression.
> 
> And then I subsequently tweaked my local copy for use in another
> project, coming up with your version.
> 
> So this passes my test harness just fine (for both even and odd array
> sizes).
> 
> Acked-by: Matt Mackall <mpm@...enic.com>

 
  I think this patch is correct. 

  Thanks
  Zou Nan hai
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/