Date: Thu, 11 Jun 2015 14:49:07 +0300 From: Stefan Andritoiu <stefan.andritoiu@gmail.com> To: =?UTF-8?Q?Roger_Pau_Monn=C3=A9?= <roger.pau@citrix.com> Cc: freebsd-virtualization@freebsd.org Subject: Re: Lock Holder Preemption on bhyve Message-ID: <CAO3d8=Zvkwf=T9MiymGOzxzACy=AziVKUD-q-c5ik-KRHBmUHw@mail.gmail.com> In-Reply-To: <5579555D.5060002@citrix.com> References: <CAO3d8=aV9ovP%2Bx2tWHSqTEGB2vK6Epano%2BqJceo7TetCsm8wLQ@mail.gmail.com> <5579555D.5060002@citrix.com>
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Hi Roger Thank you for the links, I have been looking for more information on Paravirtualized ticket spinlocks for a later project. I know how Xen handles LHP, but it does so through what are called "invasive methods", that modify the guest. For now, my work focuses on a non-invasive methods in which the guest is not aware that it is a guest. In hopes to offer a solution to LHP, regardless of the guest OS. Thank you, Stefan On Thu, Jun 11, 2015 at 12:31 PM, Roger Pau Monn=C3=A9 <roger.pau@citrix.co= m> wrote: > Hello, > > El 06/06/15 a les 0.59, Stefan Andritoiu ha escrit: >> Hello everyone, >> >> My name is Stefan Andritoiu and I'm currently studying Computer >> Science in my 4th year at the University POLITEHNICA of Bucharest. >> I'm fairly new to the FreeBSD operating system, having only a >> background in Linux. For the past few months I've been investigating >> the problem of Lock Holder Preemption on bhyve, how other hypervisors >> deal with this problem and a possible implementation of these >> solutions on bhyve. >> I am currently working on implementing Gang Scheduling on FreeBSD to >> test if it is a viable solution. I also plan to continue my work, by >> implementing and testing other techniques of avoiding overhead caused >> by lock holder preemption, and comparing their results. > > FWIW, Xen doesn't do gang-scheduling, so the lock-holder preemption > problem is solved inside of the guest by using > pvspinlocks/pvticketlocks. Not to detriment the work you are doing on > gang-scheduling, but having some like this would help FreeBSD when > running in all virtualized environments regardless of whether the > underlying hypervisor does gang-scheduling or not. Some more information > about it: > > https://blog.xenproject.org/2012/05/11/benchmarking-the-new-pv-ticketlock= -implementation/ > http://www-archive.xenproject.org/files/xensummitboston08/LHP.pdf > https://lwn.net/Articles/556141/ > > Roger.
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