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From: Tim Pepper <tpepper@gmail.com>
To: Lars Marowsky-Bree <lmb@suse.de>
Cc: device-mapper development <dm-devel@redhat.com>,
	tranlan@us.ibm.com, Linux SCSI <linux-scsi@vger.kernel.org>,
	aherrman@de.ibm.com
Subject: Re: Re: fastfail operation and retries
Date: Wed, 27 Apr 2005 15:57:09 -0700	[thread overview]
Message-ID: <eada2a0705042715573dd04ab1@mail.gmail.com> (raw)
In-Reply-To: <20050427144406.GK4431@marowsky-bree.de>

On 4/27/05, Lars Marowsky-Bree <lmb@suse.de> wrote:
> User-space needs to take action and tell us when to stop queuing.

Is there any risk of priority inversion?  I can't think of a specific
issue beyond the userspace daemon process simply not existing that
wouldn't hopefully settle out over time and I haven't looked closely
at this aspect of 2.6, but it used to be easy to get/keep the cpu busy
enough on flushing IO to disk to hurt userspace response times (fibre
pulls during heavy buffered, filesystem IO effectively DoSing the
machine for a long period).  If that sort of thing is still possible,
it seems risky relying on a userspace application for
timely/meaningful recovery of the resources consumed by the IO.

  reply	other threads:[~2005-04-27 22:57 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2005-04-21 21:33 [dm-devel] Re: fastfail operation and retries Andreas Herrmann
2005-04-21 21:38 ` David S. Miller
2005-04-21 22:24 ` Lars Marowsky-Bree
2005-04-22 19:13   ` Lan
2005-04-25 23:56     ` [dm-devel] " Tim Pepper
2005-04-27 14:44       ` Lars Marowsky-Bree
2005-04-27 22:57         ` Tim Pepper [this message]
2005-05-03 11:11           ` Lars Marowsky-Bree
2005-04-26  9:55     ` Lars Marowsky-Bree
  -- strict thread matches above, loose matches on Subject: below --
2005-04-21 22:01 goggin, edward
2005-04-21 22:16 ` Lars Marowsky-Bree
2005-04-21 21:31 goggin, edward
2005-04-21 21:49 ` Lars Marowsky-Bree
2005-04-21 21:02 goggin, edward
2005-04-19 17:19 Andreas Herrmann
2005-04-21 16:42 ` Patrick Mansfield
2005-04-21 19:54   ` Lars Marowsky-Bree
2005-04-21 22:13     ` Patrick Mansfield
2005-04-21 22:52       ` Lars Marowsky-Bree
2005-04-22  0:22         ` Patrick Mansfield

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