From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <5512FAC7.1030308@web.de> Date: Wed, 25 Mar 2015 19:13:27 +0100 From: Jan Kiszka MIME-Version: 1.0 References: <55117766.4090003@web.de> <5512D662.2030504@gmail.com> In-Reply-To: <5512D662.2030504@gmail.com> Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: quoted-printable Subject: Re: [Xenomai] xenomia on virtual box List-Id: Discussions about the Xenomai project List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Roland , xenomai@xenomai.org On 2015-03-25 16:38, Roland wrote: > Thanks Jan. > = > Will try KVM on top of PREEMPT-RT. > = > Is there a distribution particulalry suited to patch with PREEMPT-RT? Any is fine, just replace the kernel. Regarding tuning of the guest, you should try to study some basics in my original paper [1]. Details have changed, specifically QEMU has evolved a lot, but the core problem remains: prio inversion due to device emulation. Therefore, you won't see improvements in worst case latencies just by using QEMU/KVM on a PREEMPT-RT kernel. You will also have to isolate anything that triggers problematic emulations (UART, VGA, disk, ... - just virtio-net is less problematic) from RT applications in your guest via SMP, possibly also isolcpus and xenomai.supported_cpus. Given that, the question is which benefits you will get from such a setup and if the effort pays off. Jan [1] http://lwn.net/images/conf/rtlws11/papers/proc/p18.pdf -------------- next part -------------- A non-text attachment was scrubbed... Name: signature.asc Type: application/pgp-signature Size: 181 bytes Desc: OpenPGP digital signature URL: