Date: Mon, 25 Feb 2008 15:12:00 -1000 (HST) From: Jeff Roberson <jroberson@chesapeake.net> To: Brooks Davis <brooks@freebsd.org> Cc: current@freebsd.org Subject: Re: cpuset and affinity implementation Message-ID: <20080225150551.O920@desktop> In-Reply-To: <20080225233315.GA59569@lor.one-eyed-alien.net> References: <20080224173229.I920@desktop> <20080225233315.GA59569@lor.one-eyed-alien.net>
next in thread | previous in thread | raw e-mail | index | archive | help
On Mon, 25 Feb 2008, Brooks Davis wrote: > On Sun, Feb 24, 2008 at 05:38:37PM -1000, Jeff Roberson wrote: >> Hello, >> >> I have implemented a new api similar to processors sets on solaris. This >> allows you to assign processes to sets of cpus and dynamically change those >> sets. This is useful for provisioning purposes to add and remove cpu >> resources for a particular process or group of processes. This new >> facility also supports binding secific threads to specific cpus which some >> applications may want to do. At some point in the future this will be >> integrated with jail so you can restrict the cpus any jail is allowed to >> use. >> >> This api should not be considered final and the 'cpuset' tool is quite >> rough. This also only works with ULE and is unfortunately intertwined with >> a big ULE patch I've been working on. The set management code is generic >> but 4BSD doesn't contain the hooks to actually constrain threads. > > I took a look at the patch this morning. The API looks like it's > capable of doing what I need, at least at a first pass. It looks like I > should be able to implement the semantics currently employed by the Sun > Grid Engine scheduler on Irix systems. > > The one thing I noticed that I found worrying was the recursion in > cpuset_(test)update(). It wasn't immediately clear to me there there > is anything to would prevent an arbitrarily deep hierarchy from being > created and blowing the kernel stack. I'm I missing something? Yes, presently it can never be more than 3 levels deep. Once we have jails the max would be 6 levels, unless you can make jails within jails. There is presently now way for the user to create a cpuset that is a subset of another set. So the three cpu sets are: 1) Root set - immutable, all cpus, may be root of jail in which case root outside of the jail can change the set. 2) cpuset - the set this process is a member of. 3) mask - the anonymous set that is applied to an individual thread. Did you look at the userland tool at all? I think this needs the most improvement. I basically just made something that would allow me to pass every possible parameter to the api. Not exactly engineered for usability. > > -- Brooks >
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?20080225150551.O920>