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Date:      Wed, 14 Jun 2017 15:04:18 -0700 (PDT)
From:      "Rodney W. Grimes" <freebsd-rwg@pdx.rh.CN85.dnsmgr.net>
To:        "Caza, Aaron" <Aaron.Caza@ca.weatherford.com>
Cc:        Allan Jude <allanjude@freebsd.org>, "freebsd-hackers@freebsd.org" <freebsd-hackers@freebsd.org>
Subject:   Re: [EXTERNAL] Re: FreeBSD10 Stable + ZFS + PostgreSQL + SSD performance drop < 24 hours
Message-ID:  <201706142204.v5EM4IEu063454@pdx.rh.CN85.dnsmgr.net>
In-Reply-To: <f2b7a8f619f844a9bd1549bbfbeafbfa@DM2PR58MB013.032d.mgd.msft.net>

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> > -----Original Message-----
> > From: owner-freebsd-hackers@freebsd.org [mailto:owner-freebsd-hackers@f=
reebsd.org] On Behalf Of Allan Jude
> > Sent: Wednesday, June 14, 2017 11:20 AM
> > To: freebsd-hackers@freebsd.org
> > Subject: [EXTERNAL] Re: FreeBSD10 Stable + ZFS + PostgreSQL + SSD perfo=
rmance drop < 24 hours
> >
> > On 2017-06-14 13:11, Caza, Aaron wrote:
> > > Further to this:
> > >
> > > I've now tested FreeBSD 10.3-RELEASE-p19 and FreeBSD 11.0-STABLE #0 r=
307264M, both of which suffer the same degraded performance.
> > >
> > > test$ uname -a
> > > FreeBSD xyz.com 10.3-RELEASE-p19 FreeBSD 10.3-RELEASE-p19 #0 r319904M=
: Tue Jun 13 12:38:29 MDT 2017     aaronc@WFT:XYZ  amd64
> > > test$ uptime
> > > 10:15AM  up 21:09, 2 users, load averages: 1.00, 1.14, 1.30 test$ dd
> > > if=3D/testdb/test of=3D/dev/null bs=3D1m
> > > 16000+0 records in
> > > 16000+0 records out
> > > 16777216000 bytes transferred in 200.379127 secs (83727363 bytes/sec)
> > >
> > > After reboot:
> > > test$ dd if=3D/testdb/test of=3D/dev/null bs=3D1m
> > > 16000+0 records in
> > > 16000+0 records out
> > > 16777216000 bytes transferred in 23.213040 secs (722749623 bytes/sec)
> > >
> > > Same Intel Xeon E31240 with 8GB ram and 2x Samsung 850 Pro 256GB SSDs=
 as before.
> > >
> > > This message may contain confidential and privileged information. If =
it has been sent to you in error, please reply to advise the sender of the =
error and then immediately delete it. If you are not the intended recipient=
, do not read, copy, disclose=
 or otherwise use this message. The sender disclaims any liability for such=
 unauthorized use. > > PLEASE NOTE that all incoming e-mails sent to Weathe=
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>  ut this process,
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> > > _______________________________________________
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> > >
> >
> > Can you do the same test, but grab the memory lines from top(1) before =
and after each of those two runs.
> >
> > I am guessing the ARC is being squeezed out by PostgreSQL, because you =
have so little RAM.
> >
> > --
> > Allan Jude
>=20
> Takes a while for the degradation to kick in now that I rebooted this mor=
ning.
>=20
> Regarding the ARC being squeezed - well, that doesn't explain why gstat s=
hows on 95-100% busy on the drives on reboot but only ~15 %busy after the d=
egradation hits.
>=20
> In fact, ARC is being squeezed all the time because I've limited it to 50=
M in /boot/loader.conf:
> vfs.zfs.arc_min=3D"50M"
> vfs.zfs.arc_max=3D"50M"

Would you passify an old fart by at least having a delta of 1 between a min=
 and max please?
Some code may oscilate when min=3Dmax.


> Note that the FreeBSD 9.0 server that I tested on also hamstrings the ARC=
 to 50M but doesn't suffer a performance degradation hence why I hadn't bot=
hered mentioning it before.
>=20
> To remove Postgres entirely, I won't even start it and simply use dd on t=
he 16GB file.  The server is essentially doing nothing at all.
>=20
> At this point, I'm looking at going back to FreeBSD 10.3-RELEASE-p7 as ye=
sterday as 'trafdev' reported that he doesn't see any performance drop and =
he's got 95 days uptime.  He's also mentioned vfs.zfs.metaslab.lba_weightin=
g_enabled=3D0 setting which I a=
lso need to try.
>=20
> --
> Aaron
>=20
>=20
> This message may contain confidential and privileged information. If it h=
as been sent to you in error, please reply to advise the sender of the erro=
r and then immediately delete it. If you are not the intended recipient, do=
 not read, copy, disclose or=20=
otherwise use this message. The sender disclaims any liability for such una=
uthorized use. PLEASE NOTE that all incoming e-mails sent to Weatherford e-=
mail accounts will be archived and may be scanned by us and/or by external =
service providers to detect a=
nd prevent threats to our systems, investigate illegal or inappropriate beh=
avior, and/or eliminate unsolicited promotional e-mails (spam). This proces=
s could result in deletion of a legitimate e-mail before it is read by its =
intended recipient at our org=
anization. Moreover, based on the scanning results, the full text of e-mail=
s and attachments may be made available to Weatherford security and other p=
ersonnel for review and appropriate action. If you have any concerns about =
this process,
>   please contact us at dataprivacy@weatherford.com.
> _______________________________________________
> freebsd-hackers@freebsd.org mailing list
> https://lists.freebsd.org/mailman/listinfo/freebsd-hackers
> To unsubscribe, send any mail to "freebsd-hackers-unsubscribe@freebsd.org"
>=20

--=20
Rod Grimes                                                 rgrimes@freebsd.=
org



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