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

RE: [PATCH 02/37] xen: introduce a Kconfig option to configure NUMA nodes number


  • To: Jan Beulich <jbeulich@xxxxxxxx>
  • From: Wei Chen <Wei.Chen@xxxxxxx>
  • Date: Fri, 24 Sep 2021 10:33:31 +0000
  • Accept-language: en-US
  • Arc-authentication-results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=arm.com; dmarc=pass action=none header.from=arm.com; dkim=pass header.d=arm.com; arc=none
  • Arc-message-signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector9901; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version; bh=NrlQQVZM2whjIHVadx7f0f/C77QMIN1PZzvyKX895Sg=; b=J1UiPMHekcWbdEXABqBq2ygvS/B8OmmJwQ0M5BJa5dCMkhJ6/Ejpqo+hwoJJfaHc2gLf/gr6Y5IeCczQB2ZM0uDFhAILat0JPnAdWw2+8jTbLBigp2pMNsbUkkVGGcaG6AF+CZYaIgGEqMvaKCvfYgSyGsXhyZpj8mMLwsbzOsJIYi9V4w+wRvmhZ7E0Vch/9pfjX7ddHLRZTjgS+WNw0TthVWnbrXUDVolQQHCHFgT6wIK43D+vhqf0bFwy0RqqKsjKAyJ/2rSu+HiQ+6BhaW8lql1+tZ1PNSKNRV/fGBZojVFcY3S0q6qxODnVEn5rVZog+tT/9U0fPxGcKj9l5A==
  • Arc-seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=B805XAQ03J4Pp3AOwMHMaOZIMPxjs44QiOkCy3AqOvx+40z4ehpHrr09hq7ICNvMmXQG+0ELSUHSUK0PVczuCxJC6XzXLQmRWA8atq76JTezwXXtKnvGvFJDbw95Wh9tJyZgXeRj5UK2mdCQDs8LWXXnra8GjVKGGE7iVVVP6CYGzOoaLrHteJfx+GoQTjLo7QHmAAGK3mW+96d4VwPpKcpaWlLrqDhGxu3fMTccnmdekj7lBO8KdCOsfGTWgAe3Co3GXWT/kFdMPqafebqw8gwcHPmFaebGW1zpi9AQzhwohCk0AjRg4ZWdJstdmd67ZvY5LKff3BqVhEUj/cR3WQ==
  • Authentication-results-original: suse.com; dkim=none (message not signed) header.d=none;suse.com; dmarc=none action=none header.from=arm.com;
  • Cc: Bertrand Marquis <Bertrand.Marquis@xxxxxxx>, "xen-devel@xxxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxxx>, "sstabellini@xxxxxxxxxx" <sstabellini@xxxxxxxxxx>, "julien@xxxxxxx" <julien@xxxxxxx>
  • Delivery-date: Fri, 24 Sep 2021 10:34:04 +0000
  • List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
  • Nodisclaimer: true
  • Original-authentication-results: suse.com; dkim=none (message not signed) header.d=none;suse.com; dmarc=none action=none header.from=arm.com;
  • Thread-index: AQHXsHMKuuhjNuZvvk2uWABlJOqp6quy4w2AgAAazgA=
  • Thread-topic: [PATCH 02/37] xen: introduce a Kconfig option to configure NUMA nodes number

Hi Jan,

> -----Original Message-----
> From: Jan Beulich <jbeulich@xxxxxxxx>
> Sent: 2021年9月24日 16:56
> To: Wei Chen <Wei.Chen@xxxxxxx>
> Cc: Bertrand Marquis <Bertrand.Marquis@xxxxxxx>; xen-
> devel@xxxxxxxxxxxxxxxxxxxx; sstabellini@xxxxxxxxxx; julien@xxxxxxx
> Subject: Re: [PATCH 02/37] xen: introduce a Kconfig option to configure
> NUMA nodes number
> 
> On 23.09.2021 14:02, Wei Chen wrote:
> > Current NUMA nodes number is a hardcode configuration. This
> > configuration is difficult for an administrator to change
> > unless changing the code.
> >
> > So in this patch, we introduce this new Kconfig option for
> > administrators to change NUMA nodes number conveniently.
> > Also considering that not all architectures support NUMA,
> > this Kconfig option only can be visible on NUMA enabled
> > architectures. Non-NUMA supported architectures can still
> > use 1 as MAX_NUMNODES.
> 
> Do you really mean administrators here? To me command line options
> are for administrators, but build decisions are usually taken by
> build managers of distros.
> 
> > --- a/xen/arch/Kconfig
> > +++ b/xen/arch/Kconfig
> > @@ -17,3 +17,14 @@ config NR_CPUS
> >       For CPU cores which support Simultaneous Multi-Threading or
> similar
> >       technologies, this the number of logical threads which Xen will
> >       support.
> > +
> > +config NR_NUMA_NODES
> > +   int "Maximum number of NUMA nodes supported"
> > +   range 1 4095
> 
> How was this upper bound established? Seeing 4095 is the limit of the
> number of CPUs, do we really expect a CPU per node on such huge
> systems? And did you check that whichever involved data types and
> structures are actually suitable? I'm thinking e.g. of things like ...
> 
> > --- a/xen/include/asm-x86/numa.h
> > +++ b/xen/include/asm-x86/numa.h
> > @@ -3,8 +3,6 @@
> >
> >  #include <xen/cpumask.h>
> >
> > -#define NODES_SHIFT 6
> > -
> >  typedef u8 nodeid_t;
> 
> ... this.
> 

you're right, we use u8 as nodeid_t. 4095 for node number in this option
is not reasonable. Maybe a 255 upper bound is good?

> Jan


 


Rackspace

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