From: Milan Broz <mbroz@redhat.com>
To: dm-crypt@saout.de
Subject: Re: [dm-crypt] dm-crypt kills NFS performance?
Date: Thu, 21 Apr 2011 20:06:25 +0200 [thread overview]
Message-ID: <4DB07221.6020708@redhat.com> (raw)
In-Reply-To: <20110421175202.GA17024@tansi.org>
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.
Milan
next prev parent reply other threads:[~2011-04-21 18:06 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 [this message]
2011-04-21 20:26 ` Arno Wagner
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