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Date:      Sat, 4 Feb 2017 18:00:16 +0100
From:      Rainer Duffner <rainer@ultra-secure.de>
To:        Florian Ermisch <florian.ermisch@alumni.tu-berlin.de>
Cc:        freebsd-stable@freebsd.org
Subject:   Re: Problem with FreeBSD as a XenServer Guest - how to debug?
Message-ID:  <9D72A1D4-C728-4405-8101-11734D092615@ultra-secure.de>
In-Reply-To: <37CEE483-1901-4B8A-AB89-654D6C4DA6C7@alumni.tu-berlin.de>
References:  <F2B72D04-A4B1-482D-B0C7-FE9CDB26BE07@ultra-secure.de> <37CEE483-1901-4B8A-AB89-654D6C4DA6C7@alumni.tu-berlin.de>

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> Am 04.02.2017 um 10:48 schrieb Florian Ermisch =
<florian.ermisch@alumni.tu-berlin.de>:
>=20
> Hi Rainer,
>=20
> isn't Amazon AWS xen-based?
> I know Colin Percival (cperciva@) is running=20
> tarsnap.com on AWS, maybe he knows how=20
> to tune it properly?


It=E2=80=99s not a question of tuning.
It=E2=80=99s a factor of 5 that FreeBSD is slower. On SSDs, it=E2=80=99s =
10 to 15x.


> Looks like he's the one providing FreeBSD=20
> images for AWS, too: https://aws.amazon.com/marketplace/pp/B01LWSWRED/
> Amazon is probably running a heavily patched
> version of Xen but looking at the images'=20
> sysctls & stuff and running one on your Xen-
> Server might provide some insights - or at
> least datapoints.
>=20
> And then there's DTrace to dive into the=20
> kernel's inner workings*=E2=80=A6
>=20


Yes, but I don=E2=80=99t even know there to start.
My knowledge of Dtrace is very, very limited.




> Oh, does Xen still provide emulation for other
> storage controllers like SATA or SAS? If so
> you may get an at least bearable performance
> using those.


FreeBSD 10 and 11 contain the =E2=80=9Eoptimal=E2=80=9C support for Xen =
DomU support out-of-the box, AFAIK (the documentation / wiki for Xen is =
in a horrible state IMO).





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