Filesystem operations slower in 13.0 than 12.2

[Warner Losh]

On Sat, Mar 13, 2021 at 5:33 PM Kevin Oberman <rkoberman at gmail.com> wrote:

> Just spent a little time looking at my issue and have a few more notes:
>

What version did you evaluate? There's a number of changes lately that
could have a big impact on this...

Warner


> Seems to only occur on large r/w operations from/to the same disk. "sp
> big-file /other/file/on/same/disk" or tar/untar operations on large files.
> Hit this today updating firefox.
>
> I/O starts at >40MB/s. Dropped to about 1.5MB/s. If I tried doing other
> things while it was running slowly, the disk would appear to lock up. E.g.
> pwd(1) seemed to completely lock up the system, but I could still ping it
> and, after about 30 seconds, things came back to life. It was also not
> instantaneous. Disc activity dropped to <1MB/s for a few seconds before
> everything froze.
>
> During the untar of firefox, I saw; this several times. I also looked at my
> console where I found these errors during :
> swap_pager: indefinite wait buffer: bufobj: 0, blkno: 55043, size: 8192
> swap_pager: indefinite wait buffer: bufobj: 0, blkno: 51572, size: 4096
>
> I should note that some operations continue just fine while this is going
> on until I do something that freezes the system. I assume that this
> eliminates the disk drive and low-level driver. Is vfs a possible issue. It
> had some serious work in the past few months by markj. That does not
> explain why more people are not seeing this.
>
> I have been seeing this since at least September 2020, so it goes back a
> way. As this CometLake system will not run graphics on 12, I can't confirm
> operation before 13.
> --
> Kevin Oberman, Part time kid herder and retired Network Engineer
> E-mail: rkoberman at gmail.com
> PGP Fingerprint: D03FB98AFA78E3B78C1694B318AB39EF1B055683
>
>
> On Fri, Mar 5, 2021 at 10:47 PM Mark Millard via freebsd-stable <
> freebsd-stable at freebsd.org> wrote:
>
> >
> > Konstantin Belousov kostikbel at gmail.com wrote on
> > Fri Mar 5 23:12:13 UTC 2021 :
> >
> > > On Sat, Mar 06, 2021 at 12:27:55AM +0200, Christos Chatzaras wrote:
> > . . .
> > > > Command: /usr/bin/time -l portsnap extract (these tests done with 2
> > different idle servers but with same 4TB HDDs models)
> > > >
> > > > FreeBSD 12.2p4
> > > >
> > > >        99.45 real        34.90 user        59.63 sys
> > > >       100.00 real        34.91 user        59.97 sys
> > > >        82.95 real        35.98 user        60.68 sys
> > > >
> > > > FreeBSD 13.0-RC1
> > > >
> > > >       217.43 real        75.67 user       110.97 sys
> > > >       125.50 real        63.00 user        96.47 sys
> > > >       118.93 real        62.91 user        96.28 sys
> > > . . .
> > > In the portsnap results for 13RC1, the variance is too high to conclude
> > > anything, I think.
> >
> > I'll note that there are other reports of wide variance
> > in transfer rates observed during an overall operation
> > such as "make extract". The one I'm thinking of is:
> >
> >
> https://lists.freebsd.org/pipermail/freebsd-stable/2021-March/093251.html
> >
> > which is an update to earlier reports, but based on more recent
> > stable/13. https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=253968
> > comment 4 has some more notes about the context. The "make extract"
> > for firefox likely is not as complicated as the portsnap extract
> > example's execution structure.
> >
> > Might be something to keep an eye on if there are on-going
> > examples of over time.
> >
> > ===
> > Mark Millard
> > marklmi at yahoo.com
> > ( dsl-only.net went
> > away in early 2018-Mar)
> >
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> >
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