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[Xen-devel] [PATCH 0/2] blkback: Token-based QoS resource limiting for V

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Subject: [Xen-devel] [PATCH 0/2] blkback: Token-based QoS resource limiting for VBD I/O.
From: William Pitcock <nenolod@xxxxxxxxxxxxxxxx>
Date: Tue, 31 Mar 2009 09:25:59 -0500
Delivery-date: Tue, 31 Mar 2009 08:40:12 -0700
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This patch series is a completed version of the I/O QoS work that I have
been doing in the blkback driver. The end goal of this work is to enable
constructs in the vm config file to define a ratelimiting policy for I/O

This is important because on systems where LVM+AoE are used, I/O performance
is a larger challenge than with local disks. As such, the ability to reduce
the effects of guests performing a lot of I/O operations is desirable.

This patch series was inspired by the UML 'token-limiter' patch, which was
developed with a similar rationale. However, unlike the token-limiter patch
the QoS limitation is enforced in the backend, which allows any paravirtualized
guest to be run without the ability of getting around the QoS limits.

This patch series provides the host kernel side. Patches to xend will
be necessary, and it may be desirable to see the QoS stats in the guest.
However, the guest side (blkfront) would need to be modified to display
these stats.

William Pitcock (2):
  blkback: Implement VBD QoS mechanics.
  blkback: Read "tokens-refill", and "tokens-max" xenstore values to
    provide QoS parameters per device.

 drivers/xen/blkback/blkback.c |   22 ++++++++++++++++++++++
 drivers/xen/blkback/common.h  |    6 ++++++
 drivers/xen/blkback/xenbus.c  |    5 +++++
 3 files changed, 33 insertions(+), 0 deletions(-)

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