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Date:      Wed, 22 Aug 2018 09:38:05 +0000
From:      Wei Hu <weh@microsoft.com>
To:        Support SimpleRezo <simplerezo@gmail.com>
Cc:        "freebsd-virtualization@freebsd.org" <freebsd-virtualization@freebsd.org>
Subject:   RE: [HyperV-2016] urandom performance issue...
Message-ID:  <PU1P153MB0153ECB9C43DC68C64928AE5BB300@PU1P153MB0153.APCP153.PROD.OUTLOOK.COM>
In-Reply-To: <20180822003512.GI97145@funkthat.com>
References:  <CALVu1vZ3iSFDt60mLVie_17rejNeXggjDOGdY7HuYeRGmMxM=w@mail.gmail.com> <20180822003512.GI97145@funkthat.com>

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Have you ever seen the same issue on Hyper-V 2012? What is the Windows vers=
ion what you are running into the issue?

Thanks,
Wei

-----Original Message-----
From: owner-freebsd-virtualization@freebsd.org <owner-freebsd-virtualizatio=
n@freebsd.org> On Behalf Of John-Mark Gurney
Sent: Wednesday, August 22, 2018 8:35 AM
To: Support SimpleRezo <simplerezo@gmail.com>
Cc: freebsd-virtualization@freebsd.org
Subject: Re: [HyperV-2016] urandom performance issue...

Support SimpleRezo wrote this message on Tue, Aug 21, 2018 at 19:06 +0200:
> I was figuring a performance issue of a FreeBSD on HyperV, after:
>   - moving it from an Hyper-V 2012 host to a Hyper-V 2016
>   - updating to FreeBSD 11.2 (custom kernel, but same issue with=20
> GENERIC) After loosing some times because i was thinking about=20
> hardware issue (disk controller was my first thought...) and testing=20
> with "dd if=3D/dev/urandom"... I discovered this...
>=20
> I ran the following test... and quite surprised by the speed result!
> $ dd if=3D/dev/urandom of=3D/dev/null bs=3D10M count=3D3
> 3+0 records in
> 3+0 records out
> 31457280 bytes transferred in 27.960431 secs (1125064 bytes/sec) The=20
> test was also sometimes "freezing" the Hyper-V host!
>=20
> Looking into "dmesg" i have found this:
> random: registering fast source Intel Secure Key RNG
> random: fast provider: "Intel Secure Key RNG"
>=20
> So I rebuilt my KERNEL without "rdrand_rng" (didn't find another way=20
> to disable it...)... and performances went back to normal!
>=20
> I think this issue should documented on https://na01.safelinks.protection=
.outlook.com/?url=3Dhttps%3A%2F%2Fwiki.freebsd.org%2FHyperV&amp;data=3D02%7=
C01%7Cweh%40microsoft.com%7Cc42c865cb80e4ed2c95f08d607c74577%7C72f988bf86f1=
41af91ab2d7cd011db47%7C1%7C0%7C636704949779065690&amp;sdata=3DWaGPCp%2FggDU=
QMyrk49GAbe8TypqYGdpV2tgTg3sTqvk%3D&amp;reserved=3D0 !

This is likely the same issue as:
https://na01.safelinks.protection.outlook.com/?url=3Dhttps%3A%2F%2Fbugs.fre=
ebsd.org%2Fbugzilla%2Fshow_bug.cgi%3Fid%3D230808&amp;data=3D02%7C01%7Cweh%4=
0microsoft.com%7Cc42c865cb80e4ed2c95f08d607c74577%7C72f988bf86f141af91ab2d7=
cd011db47%7C1%7C0%7C636704949779065690&amp;sdata=3Dnm3oeJoKGlYzD0ZcSPhGCEw1=
rMgbsrGkem69AYA2hoI%3D&amp;reserved=3D0

If you're having troubles w/ the host freezing, this should probably still =
be investigated as even w/ the excessive locking, it should never freeze.

--=20
  John-Mark Gurney				Voice: +1 415 225 5579

     "All that I will do, has been done, All that I have, has not."
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