On 04/01/16 03:01, Dave Chinner wrote:
> Can you go back to your original kernel, and lower nr_requests to 8?
Sure, did that and as expected it didn't help much. Under prolonged stress
it was actually even a bit worse than writeback throttling. IMHO that's not
really surprising either, since small
On 04/01/2016 12:27 AM, Dave Chinner wrote:
On Thu, Mar 31, 2016 at 09:25:33PM -0600, Jens Axboe wrote:
On 03/31/2016 06:46 PM, Dave Chinner wrote:
virtio in guest, XFS direct IO -> no-op -> scsi in host.
That has write back caching enabled on the guest, correct?
No. It uses virtio,cache=no
On 04/01/2016 12:16 AM, Dave Chinner wrote:
On Thu, Mar 31, 2016 at 09:39:25PM -0600, Jens Axboe wrote:
On 03/31/2016 09:29 PM, Jens Axboe wrote:
I can't seem to reproduce this at all. On an nvme device, I get a
fairly steady 60K/sec file creation rate, and we're nowhere near
being IO bound. So
On Thu, Mar 31, 2016 at 09:25:33PM -0600, Jens Axboe wrote:
> On 03/31/2016 06:46 PM, Dave Chinner wrote:
> >>>virtio in guest, XFS direct IO -> no-op -> scsi in host.
> >>
> >>That has write back caching enabled on the guest, correct?
> >
> >No. It uses virtio,cache=none (that's the "XFS Direct IO
On Thu, Mar 31, 2016 at 09:39:25PM -0600, Jens Axboe wrote:
> On 03/31/2016 09:29 PM, Jens Axboe wrote:
> >>>I can't seem to reproduce this at all. On an nvme device, I get a
> >>>fairly steady 60K/sec file creation rate, and we're nowhere near
> >>>being IO bound. So the throttling has no effect a
On Thu, Mar 31, 2016 at 09:29:30PM -0600, Jens Axboe wrote:
> On 03/31/2016 06:56 PM, Dave Chinner wrote:
> >I'm not changing the host kernels - it's a production machine and so
> >it runs long uptime testing of stable kernels. (e.g. catch slow
> >memory leaks, etc). So if you've disabled throttli
On 03/31/2016 09:29 PM, Jens Axboe wrote:
I can't seem to reproduce this at all. On an nvme device, I get a
fairly steady 60K/sec file creation rate, and we're nowhere near
being IO bound. So the throttling has no effect at all.
That's too slow to show the stalls - your likely concurrency bound
On 03/31/2016 09:29 PM, Jens Axboe wrote:
I'm not changing the host kernels - it's a production machine and so
it runs long uptime testing of stable kernels. (e.g. catch slow
memory leaks, etc). So if you've disabled throttling in the guest, I
can't test the throttling changes.
Right, that'd d
On 03/31/2016 06:56 PM, Dave Chinner wrote:
On Thu, Mar 31, 2016 at 10:21:04AM -0600, Jens Axboe wrote:
On 03/31/2016 08:29 AM, Jens Axboe wrote:
What I see in these performance dips is the XFS transaction
subsystem stalling *completely* - instead of running at a steady
state of around 350,000
On 03/31/2016 06:46 PM, Dave Chinner wrote:
On Thu, Mar 31, 2016 at 08:29:35AM -0600, Jens Axboe wrote:
On 03/31/2016 02:24 AM, Dave Chinner wrote:
On Wed, Mar 30, 2016 at 09:07:48AM -0600, Jens Axboe wrote:
Hi,
This patchset isn't as much a final solution, as it's demonstration
of what I bel
On Thu, Mar 31, 2016 at 10:09:56PM +, Holger Hoffstätte wrote:
>
> Hi,
>
> Jens mentioned on Twitter I should post my experience here as well,
> so here we go.
>
> I've backported this series (incl. updates) to stable-4.4.x - not too
> difficult, minus the NVM part which I don't need anyway
On Thu, Mar 31, 2016 at 10:21:04AM -0600, Jens Axboe wrote:
> On 03/31/2016 08:29 AM, Jens Axboe wrote:
> >>What I see in these performance dips is the XFS transaction
> >>subsystem stalling *completely* - instead of running at a steady
> >>state of around 350,000 transactions/s, there are *zero*
>
On Thu, Mar 31, 2016 at 08:29:35AM -0600, Jens Axboe wrote:
> On 03/31/2016 02:24 AM, Dave Chinner wrote:
> >On Wed, Mar 30, 2016 at 09:07:48AM -0600, Jens Axboe wrote:
> >>Hi,
> >>
> >>This patchset isn't as much a final solution, as it's demonstration
> >>of what I believe is a huge issue. Since
Hi,
Jens mentioned on Twitter I should post my experience here as well,
so here we go.
I've backported this series (incl. updates) to stable-4.4.x - not too
difficult, minus the NVM part which I don't need anyway - and have been
running it for the past few days without any problem whatsoever, wi
On 03/31/2016 08:29 AM, Jens Axboe wrote:
What I see in these performance dips is the XFS transaction
subsystem stalling *completely* - instead of running at a steady
state of around 350,000 transactions/s, there are *zero*
transactions running for periods of up to ten seconds. This
co-incides w
On 03/31/2016 02:24 AM, Dave Chinner wrote:
On Wed, Mar 30, 2016 at 09:07:48AM -0600, Jens Axboe wrote:
Hi,
This patchset isn't as much a final solution, as it's demonstration
of what I believe is a huge issue. Since the dawn of time, our
background buffered writeback has sucked. When we do bac
On Wed, Mar 30, 2016 at 09:07:48AM -0600, Jens Axboe wrote:
> Hi,
>
> This patchset isn't as much a final solution, as it's demonstration
> of what I believe is a huge issue. Since the dawn of time, our
> background buffered writeback has sucked. When we do background
> buffered writeback, it shou
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