svn commit: r322863 - head/sys/cam

[Warner Losh]

On Fri, Aug 25, 2017 at 9:46 AM, Slawa Olhovchenkov <slw at zxy.spb.ru> wrote:

> On Fri, Aug 25, 2017 at 09:33:35AM -0600, Warner Losh wrote:
>
> > On Fri, Aug 25, 2017 at 7:35 AM, Slawa Olhovchenkov <slw at zxy.spb.ru>
> wrote:
> >
> > > On Thu, Aug 24, 2017 at 10:11:10PM +0000, Warner Losh wrote:
> > >
> > > > Author: imp
> > > > Date: Thu Aug 24 22:11:10 2017
> > > > New Revision: 322863
> > > > URL: https://svnweb.freebsd.org/changeset/base/322863
> > > >
> > > > Log:
> > > >   Expand the latency tracking array from 1.024s to 8.192s to help
> track
> > > >   extreme outliers from dodgy drives. Adjust comments to reflect
> this,
> > > >   and make sure that the number of latency buckets match in the two
> > > >   places where it matters.
> > >
> > > May be up to 1min?
> > >
> >
> > I'm not sure what additional data you'll get between "totally sucks, at
> > least 8s latency" and "totally sucks, at least 32s." or "totally sucks,
> at
> > least 64s" though the latter isn't possible with the default timeouts...
> >
> > I'm planning on adding a 'max' latency that's self-resetting instead of
> > expanding the bucket upwards. I'm also contemplating expanding it down to
> > 100us or even 10us since nda serves nvme drives which easily can be sub
> > 100us.
>
> This is just stat data?
> Don't produce error messages about timeout commands and etc?
>

This is 100% stats. There's no error messages produced.

Warner