From: Arno Wagner <arno@wagner.name>
To: dm-crypt@saout.de
Subject: Re: [dm-crypt] dm-crypt kills NFS performance?
Date: Thu, 21 Apr 2011 22:26:47 +0200 [thread overview]
Message-ID: <20110421202647.GA20092@tansi.org> (raw)
In-Reply-To: <4DB07221.6020708@redhat.com>
On Thu, Apr 21, 2011 at 08:06:25PM +0200, Milan Broz wrote:
> On 04/21/2011 07:52 PM, Arno Wagner wrote:
> >
> > This sounds like one more problems with the Big Kernel Lock.
> > The basic problem (simplified) is that some operations
> > block everything while running. dm-crypt and RAID makes
> > them take longer, but the problem is the blocking.
>
> It can be many problems, from network card driver to
> nfs handling or io scheduler setting.
>
> For dm-crypt (kcryptd) - it doesn't not use BKL at all
> and after every sector encryption it calls cond_resched()
> (hinting scheduler to switch process if there is other work
> even if kernel is compiled with voluntary preemption).
> So it should behave correctly under load.
Ah. Good to know.
Arno
--
Arno Wagner, Dr. sc. techn., Dipl. Inform., CISSP -- Email: arno@wagner.name
GnuPG: ID: 1E25338F FP: 0C30 5782 9D93 F785 E79C 0296 797F 6B50 1E25 338F
----
Cuddly UI's are the manifestation of wishful thinking. -- Dylan Evans
If it's in the news, don't worry about it. The very definition of
"news" is "something that hardly ever happens." -- Bruce Schneier
prev parent reply other threads:[~2011-04-21 20:26 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-04-21 17:14 [dm-crypt] dm-crypt kills NFS performance? Randall Cotton
2011-04-21 17:52 ` Arno Wagner
2011-04-21 18:06 ` Milan Broz
2011-04-21 20:26 ` Arno Wagner [this message]
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