[dm-devel] [PATCH 14/15] multipath-tools: replace queue-length by default selector

[Christophe Varoqui]

I agree with Hannes on this.

The default values are not meant to provide optimal performance ... they
are meant to provide an accessible LUN whatever the hardware and on the
broader range of Linux kernels. Vendors are responsible to provide their
array tuning as hwtable entries. And the size or factorization of the
hwtable is not an issue.


On Thu, Aug 11, 2016 at 7:58 AM, Hannes Reinecke <hare at suse.de> wrote:

> On 08/10/2016 06:20 PM, Xose Vazquez Perez wrote:
> > service-time is more advanced, and it works better in asymmetric and
> > asymmetric environments.
> >
> > Cc: Hannes Reinecke <hare at suse.de>
> > Cc: Benjamin Marzinski <bmarzins at redhat.com>
> > Cc: Christophe Varoqui <christophe.varoqui at opensvc.com>
> > Cc: device-mapper development <dm-devel at redhat.com>
> > Signed-off-by: Xose Vazquez Perez <xose.vazquez at gmail.com>
> > ---
> >  libmultipath/hwtable.c | 2 --
> >  1 file changed, 2 deletions(-)
> >
> > diff --git a/libmultipath/hwtable.c b/libmultipath/hwtable.c
> > index bc2d407..edfd8fe 100644
> > --- a/libmultipath/hwtable.c
> > +++ b/libmultipath/hwtable.c
> > @@ -198,7 +198,6 @@ static struct hwentry default_hw[] = {
> >       {
> >               .vendor        = "XtremIO",
> >               .product       = "XtremApp",
> > -             .selector      = "queue-length 0",
> >               .pgpolicy      = MULTIBUS,
> >               .pgfailback    = FAILBACK_UNDEF,
> >       },
> > @@ -823,7 +822,6 @@ static struct hwentry default_hw[] = {
> >       {
> >               .vendor        = "PURE",
> >               .product       = "FlashArray",
> > -             .selector      = "queue-length 0",
> >               .pgpolicy      = MULTIBUS,
> >               .pgfailback    = FAILBACK_UNDEF,
> >               .fast_io_fail  = 10,
> >
> I would _not_ do this, unless tested on the real hardware.
> Just claiming 'the other one is more advanced' is not enough here.
>
> NACK.
>
> Cheers,
>
> Hannes
> --
> Dr. Hannes Reinecke                Teamlead Storage & Networking
> hare at suse.de                                   +49 911 74053 688
> SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
> GF: F. Imendörffer, J. Smithard, J. Guild, D. Upmanyu, G. Norton
> HRB 21284 (AG Nürnberg)
>
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