ACK/cmnt: [SRU cosmic-aws][PATCH 0/6] LP: #1801305: xen-blkfront: restore request mode
kleber.souza at canonical.com
Wed Nov 7 17:22:17 UTC 2018
On 11/02/18 09:57, Daniel Axtens wrote:
> In current Ubuntu kernels, PV blkfront drivers have blk-mq enabled by
> default and cannot use the old I/O scheduler.
> blk-mq is not as fast as the old request-based scheduler for some
> workloads on HDD disks.
> Amazon Linux has a commit which reintroduces the request-based
> mode. It disables blk-mq by default but allows it to be switched back
> on with a kernel parameter.
> For X this needs a small patch from upstream for error handling.
> For B/C this patchset is bigger as it includes the suspend/resume
> patches already in X, and a new fixup. These are desirable as the
> request mode patch assumes their presence.
> [Regression Potential]
> Could potentially break xen based disks on AWS.
> For B/C, the patches also add some code to the xen core around suspend
> and resume, this code is much smaller and also mirrors code already in
> Tested by AWS for Xenial, and their kernel engineers vetted the Xenial
> patches. I tested the Bionic and Cosmic patchsets with fio, the system
> appears stable and the IOPS promised for EBS Provisioned IOPS disks
> were met in my testing. I did an apt update/upgrade and everything
> worked (no hash-sum mismatches).
> Anchal Agarwal (1):
> xen-blkfront: Fixed blkfront_restore to remove a call to negotiate_mq
> Munehisa Kamata (5):
> xen/manage: keep track of the on-going suspend mode
> xen/manage: introduce helper function to know the on-going suspend
> xenbus: add freeze/thaw/restore callbacks support
> xen-blkfront: add callbacks for PM suspend and hibernation
> xen-blkfront: resurrect request-based mode
> drivers/block/xen-blkfront.c | 475 ++++++++++++++++++++++++++----
> drivers/xen/manage.c | 73 +++++
> drivers/xen/xenbus/xenbus_probe.c | 102 ++++++-
> include/xen/xen-ops.h | 4 +
> include/xen/xenbus.h | 3 +
> 5 files changed, 576 insertions(+), 81 deletions(-)
The patches probably need a SAUCE tag since they don't seems to come
Acked-by: Kleber Sacilotto de Souza <kleber.souza at canonical.com>
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