From: Milan Broz <mbroz@redhat.com>
To: Kyle Rose <krose@krose.org>
Cc: dm-crypt <dm-crypt@saout.de>
Subject: Re: [dm-crypt] FSB saturation?
Date: Sat, 14 May 2011 17:30:58 +0200 [thread overview]
Message-ID: <4DCEA032.1030207@redhat.com> (raw)
In-Reply-To: <BANLkTimMGF-fKzoyrrWKd-f4TR_ohANRbw@mail.gmail.com>
On 05/14/2011 04:36 PM, Kyle Rose wrote:
> For the past week I've been trying to figure out why my
> dm-crypt-on-RAID6 performance is so terrible. To wit:
>
> root@yupa:/source# hdparm -t /dev/md1
>
> /dev/md1: <---the RAID 6 block device
> Timing buffered disk reads: 1262 MB in 3.00 seconds = 420.19 MB/sec
>
> root@yupa:/source# hdparm -t /dev/mapper/yupa
>
> /dev/mapper/yupa: <---the dm-crypt device with /dev/md1 as the underlying store
> Timing buffered disk reads: 370 MB in 3.00 seconds = 123.26 MB/sec
IIRC hdparm is doing direct io of size 2MB.
Can you try do the same but with dd (just dd from device without direct mode).
like "dd if=/dev/md1 of=/dev/null bs=64k count=4096"
Gives it better throughput now? (on 2.6.38 and above)
Milan
next prev parent reply other threads:[~2011-05-14 15:31 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-05-14 14:36 [dm-crypt] FSB saturation? Kyle Rose
2011-05-14 15:30 ` Milan Broz [this message]
2011-05-14 15:35 ` Kyle Rose
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