From: Paolo Bonzini <pbonzini@redhat.com>
To: Oleg Ovechko <ovechko.spam@gmail.com>
Cc: qemu-discuss@nongnu.org, kvm@vger.kernel.org
Subject: Re: Why do additional cores reduce performance?
Date: Tue, 16 Dec 2014 17:31:13 +0100 [thread overview]
Message-ID: <54905E51.10600@redhat.com> (raw)
In-Reply-To: <CAGwhzhGDJksiBE6b7Kxf6P7gFKaEG8H-t7xCWG+ZZLQkWqZwYw@mail.gmail.com>
On 16/12/2014 17:22, Oleg Ovechko wrote:
>> What is your benchmark?
>
> I've tried different ways (CrystalDiskMark 3.0.3 x64, ATTO Disk
> Banchmark v2.47) all give same result.
All are run on the AHCI passthrough disk(s), right?
> When everything is enabled in BIOS it is 6:23 on real Windows versus
> 9:03 on virtualized...
>
> Phil Ehrens has sent me link
> https://lists.gnu.org/archive/html/qemu-discuss/2014-10/msg00036.html
> If I don't misunderstand, it means kvm/qemu simply is not designed for
> multi-threading.
No, it means TCG does not support multithreading. KVM does, and you are
using it.
> I guess I need to try different hypervisor. 50% performance is too
> high price especially when VT-x and VT-d are meant to make it 0%
It is surprising to me too.
Paolo
next prev parent reply other threads:[~2014-12-16 16:31 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-12-15 23:40 Why do additional cores reduce performance? Oleg Ovechko
2014-12-16 9:26 ` Paolo Bonzini
2014-12-16 16:22 ` Oleg Ovechko
2014-12-16 16:31 ` Paolo Bonzini [this message]
-- strict thread matches above, loose matches on Subject: below --
2014-12-15 23:33 Oleg Ovechko
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