From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:45923) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Vlhqi-0005Qc-Ky for qemu-devel@nongnu.org; Wed, 27 Nov 2013 11:20:30 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Vlhqc-0002iV-M3 for qemu-devel@nongnu.org; Wed, 27 Nov 2013 11:20:24 -0500 Received: from mx1.redhat.com ([209.132.183.28]:41381) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Vlhqc-0002hl-Dl for qemu-devel@nongnu.org; Wed, 27 Nov 2013 11:20:18 -0500 Date: Wed, 27 Nov 2013 17:19:52 +0100 From: Andrew Jones Message-ID: <20131127161952.GA11571@hawk.usersys.redhat.com> References: <1385086118-11699-1-git-send-email-gaowanlong@cn.fujitsu.com> <1385086118-11699-11-git-send-email-gaowanlong@cn.fujitsu.com> <52960349.5020603@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <52960349.5020603@redhat.com> Subject: Re: [Qemu-devel] [PATCH V16 09/11] NUMA: set guest numa nodes memory policy List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Paolo Bonzini Cc: ehabkost@redhat.com, lersek@redhat.com, mtosatti@redhat.com, qemu-devel@nongnu.org, lcapitulino@redhat.com, bsd@redhat.com, anthony@codemonkey.ws, hutao@cn.fujitsu.com, y-goto@jp.fujitsu.com, peter.huangpeng@huawei.com, afaerber@suse.de, Wanlong Gao On Wed, Nov 27, 2013 at 03:35:53PM +0100, Paolo Bonzini wrote: > > + > > + len = numa_info[nodeid].node_mem; > > + bind_mode = node_parse_bind_mode(nodeid); > > + unsigned long *nodes = numa_info[nodeid].host_mem; > > + > > + /* This is a workaround for a long standing bug in Linux' > > + * mbind implementation, which cuts off the last specified > > + * node. To stay compatible should this bug be fixed, we > > + * specify one more node and zero this one out. > > + */ > > + unsigned long maxnode = find_last_bit(nodes, MAX_NODES); > > + if (syscall(SYS_mbind, ram_ptr + ram_offset, len, bind_mode, > > + nodes, maxnode + 2, 0)) { > > + perror("mbind"); > > + return -1; > > + } > > Also, it's still not clear to me why we're not using libnuma. > There only seem to be two reasons to use it right now; 1) it provides a wrapper around mbind 2) it exists. IMHO libnuma needs some work before it would be suitable for qemu to marry it. Its interfaces don't buy a lot of elegance, it only reads system information on link time (i.e. no good if you want to consider hotplug of cpus and nodes), and it's currently linux specific anyway. It's a good idea, but is it worth yet another qemu build dependency? drew