[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Xen-devel] Cpupools and pdata_alloc


  • To: George Dunlap <George.Dunlap@xxxxxxxxxxxxx>
  • From: Juergen Gross <juergen.gross@xxxxxxxxxxxxxx>
  • Date: Tue, 11 May 2010 06:48:49 +0200
  • Cc: xen-devel@xxxxxxxxxxxxxxxxxxx, Keir Fraser <keir.fraser@xxxxxxxxxxxxx>
  • Delivery-date: Mon, 10 May 2010 21:50:02 -0700
  • Domainkey-signature: s=s1536a; d=ts.fujitsu.com; c=nofws; q=dns; h=X-SBRSScore:X-IronPort-AV:Received:X-IronPort-AV: Received:Received:Message-ID:Date:From:Organization: User-Agent:MIME-Version:To:CC:Subject:References: In-Reply-To:Content-Type:Content-Transfer-Encoding; b=op7TwVwQe2PlJz58qUDud/H15lkzbXHXrptAsrcEUKcWedD+YCnrByks wp+AXh1dBXifao+yizKpxM8bKI8Rr+xtjDuoNKdrOr4/ENzJHhyrhEZ3L NyvlCKdsOS7KMlEcxXEMiiHCElwv3wdGe6vHpqjKIIf0ilPfgQpHjGgQ9 BTegTF9t11IX72l9izbxquf9Sk6I9ROQvzslDn5FCu4zDMzL06T4jeoLu Z9SA7pNdbOUh1QyXH2itAj/EzGNbN;
  • List-id: Xen developer discussion <xen-devel.lists.xensource.com>

On 05/10/2010 07:47 PM, George Dunlap wrote:
It appears that in the new cpupools code:
* pdata_allocate is called from alloc_vcpu() with that cpu for the first time.
* this happens usually when dom0's cpus are allocated, as it cycles
through all of the cpus

No. It happens when idle vcpus are allocated. At this time there is no cpupool
existing, all physical cpus are marked as "free", e.g. they are in no pool at
all.
Dom0 vcpus are allocated in Pool-0. This pool is created after allocation of
the idle vcpus.


This seems a bit strange to me.  Wouldn't it make more sense to pass,
or to make available, a cpumask of the cpus in a pool to the init
function?

No. A cpupool is created without any cpu in the beginning. Whenever a cpu is
added to a cpupool, alloc_pdata is called for this cpu.

BTW: Allocating the percpu data of the scheduler during the allocation of the
first vcpu on this cpu was in sched_credit.c before cpupools were introduced.


Also, is there documentation of the cpupool lifecycle anywhere, to
help scheduler writers understand what's going on?

Not yet.
I'll write something up in the next days.


Juergen

--
Juergen Gross                 Principal Developer Operating Systems
TSP ES&S SWE OS6                       Telephone: +49 (0) 89 3222 2967
Fujitsu Technology Solutions              e-mail: juergen.gross@xxxxxxxxxxxxxx
Domagkstr. 28                           Internet: ts.fujitsu.com
D-80807 Muenchen                 Company details: ts.fujitsu.com/imprint.html

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel


 


Rackspace

Lists.xenproject.org is hosted with RackSpace, monitoring our
servers 24x7x365 and backed by RackSpace's Fanatical Support®.