Re: [Qemu-devel] [PATCH v18 13/14] memory backend: fill memory backend ram fields

[Hu Tao <hutao@cn.fujitsu.com>]

On Tue, Feb 25, 2014 at 06:09:20PM +0800, Hu Tao wrote:
> On Wed, Feb 19, 2014 at 10:03:13AM +0100, Paolo Bonzini wrote:
> 
> <...>
> 
> > > static int
> > > ram_backend_memory_init(HostMemoryBackend *backend, Error **errp)
> > > {
> > >+    HostMemoryBackendRam *ram_backend = MEMORY_BACKEND_RAM(backend);
> > >+    int mode = ram_backend->policy;
> > >+    void *p;
> > >+    unsigned long maxnode;
> > >+
> > >     if (!memory_region_size(&backend->mr)) {
> > >         memory_region_init_ram(&backend->mr, OBJECT(backend),
> > >                                object_get_canonical_path(OBJECT(backend)),
> > >                                backend->size);
> > >+
> > >+        p = memory_region_get_ram_ptr(&backend->mr);
> > >+        maxnode = find_last_bit(ram_backend->host_nodes, MAX_NODES);
> > >+
> > >+        mode |= ram_backend->relative ? MPOL_F_RELATIVE_NODES :
> > >+            MPOL_F_STATIC_NODES;
> > >+        /* 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.
> > >+         */
> > >+        if (syscall(SYS_mbind, p, backend->size, mode,
> > >+                    ram_backend->host_nodes, maxnode + 2, 0)) {
> > 
> > This does not compile on non-Linux; also, does libnuma include the
> > workaround?  If so, this is a hint that we should be using libnuma
> > instead...
> 
> Tested with libnuma and works fine without the workaround. Will use
> libnuma in v19.

Sorry I might do something wrong about the test. With libnuma the
workaround is still needed. I checked numactl-2.0.9, it doesn't include
the workaround.