ACK/cmnt: [SRU xenial-aws][PATCH 0/2] LP: #1801305: xen-blkfront: restore request mode
daniel.axtens at canonical.com
Thu Nov 8 00:20:12 UTC 2018
Good catch. Would you like me to resubmit the 3 series with this
fixed? If so, do I include the existing ACKs, or is there any tooling
that depends on the particular messages with the particular subjects
being in someone's inbox?
On Thu, Nov 8, 2018 at 4:24 AM Kleber Souza <kleber.souza at canonical.com> wrote:
> On 11/02/18 10:01, Daniel Axtens wrote:
> > In current Ubuntu kernels, PV blkfront drivers have blk-mq enabled by
> > default and cannot use the old I/O scheduler.
> > [Impact]
> > blk-mq is not as fast as the old request-based scheduler for some
> > workloads on HDD disks.
> > [Fix]
> > 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
> > Xenial.
> > [Tests]
> > 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).
> > Christoph Hellwig (1):
> > xen-blkfront: don't use req->errors
> > Munehisa Kamata (1):
> > xen-blkfront: resurrect request-based mode
> > drivers/block/xen-blkfront.c | 333 +++++++++++++++++++++++++++++------
> > 1 file changed, 276 insertions(+), 57 deletions(-)
> Patch 2/2 probably need a SAUCE tag since it doesn't seem to come
> from mainline.
> Acked-by: Kleber Sacilotto de Souza <kleber.souza at canonical.com>
More information about the kernel-team