linux-kernel - Re: [patch 04/17] Add pagetable accessors to pack and unpack pagetable entries

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:	Wed, 4 Apr 2007 17:46:55 +0200
From:	Ingo Molnar <mingo@...e.hu>
To:	Jeremy Fitzhardinge <jeremy@...p.org>
Cc:	Andi Kleen <ak@...e.de>, Andrew Morton <akpm@...ux-foundation.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	lkml <linux-kernel@...r.kernel.org>
Subject: Re: [patch 04/17] Add pagetable accessors to pack and unpack pagetable entries


* Jeremy Fitzhardinge <jeremy@...p.org> wrote:

> Ingo Molnar wrote:
> > the main metric we are interested in is the overhead for people who just 
> > want to run the non-patched native kernel that has CONFIG_PARAVIRT 
> > enabled (99%+ of the users at the moment), so the delta is:
> >
> >  null:              +12.0%
> >  null IO:            +7.5%
> >  stat:        within noise
> >  open/close:  within noise
> >  TCP:                ~5.0%
> >  signal install:      2.0%
> >  signal handle:       4.7%
> >  fork:                2.7%
> >  exec:                3.6%
> >  shell:               3.6%
> >   
>
> Hm, I don't think you can get this much precision out of these 
> numbers. I noticed larger variations from boot-to-boot running the 
> same test.

sure. i simply took the middle numbers. But there's definitely a 'few 
percents' trend in the numbers.

> > this is not 'barely measurable' but 'BLOODY LARGE' overhead.
> 
> Yes.  Fortunately there's a noticable difference between native and 
> unpatched paravirt, because it shows all the effort we put into 
> patching is worthwhile.

if only it were not such an ugly piece of code? ;)

	Ingo
-
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/