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Re: [Qemu-devel] [PATCH V16 09/11] NUMA: set guest numa nodes memory pol
From: |
Andrew Jones |
Subject: |
Re: [Qemu-devel] [PATCH V16 09/11] NUMA: set guest numa nodes memory policy |
Date: |
Wed, 27 Nov 2013 17:19:52 +0100 |
User-agent: |
Mutt/1.5.21 (2010-09-15) |
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
- [Qemu-devel] [PATCH] fixup, (continued)
- [Qemu-devel] [PATCH] fixup, Wanlong Gao, 2013/11/21
- [Qemu-devel] [PATCH V16 04/11] NUMA: convert -numa option to use OptsVisitor, Wanlong Gao, 2013/11/21
- [Qemu-devel] [PATCH V16 03/11] NUMA: Add numa_info structure to contain numa nodes info, Wanlong Gao, 2013/11/21
- [Qemu-devel] [PATCH V16 08/11] NUMA: parse guest numa nodes memory policy, Wanlong Gao, 2013/11/21
- [Qemu-devel] [PATCH V16 10/11] NUMA: add qmp command query-numa, Wanlong Gao, 2013/11/21
- [Qemu-devel] [PATCH V16 01/11] NUMA: move numa related code to new file numa.c, Wanlong Gao, 2013/11/21
- [Qemu-devel] [PATCH V16 09/11] NUMA: set guest numa nodes memory policy, Wanlong Gao, 2013/11/21
- [Qemu-devel] [PATCH V16 07/11] NUMA: expand MAX_NODES from 64 to 128, Wanlong Gao, 2013/11/21
- [Qemu-devel] [PATCH V16 11/11] NUMA: convert hmp command info_numa to use qmp command query_numa, Wanlong Gao, 2013/11/21