Date: Thu, 11 Jun 2015 11:31:09 +0200 From: =?windows-1252?Q?Roger_Pau_Monn=E9?= <roger.pau@citrix.com> To: Stefan Andritoiu <stefan.andritoiu@gmail.com>, <freebsd-virtualization@freebsd.org> Subject: Re: Lock Holder Preemption on bhyve Message-ID: <5579555D.5060002@citrix.com> In-Reply-To: <CAO3d8=aV9ovP%2Bx2tWHSqTEGB2vK6Epano%2BqJceo7TetCsm8wLQ@mail.gmail.com> References: <CAO3d8=aV9ovP%2Bx2tWHSqTEGB2vK6Epano%2BqJceo7TetCsm8wLQ@mail.gmail.com>
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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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