Dario Faggioli wrote:
> Starting from Xen 4.2, libxl has all the bits and pieces in place
> for retrieving an adequate amount of information about the host
> NUMA topology. It is therefore possible, after a bit of shuffling,
> to arrange those information in the way libvirt wants to present
> them to the outside world.
>
> Therefore, with this patch, the <topology> section of the host
> capabilities is properly populated, when running on Xen, so that
> we can figure out whether or not we're running on a NUMA host,
> and what its characteristics are.
>
> [raistlin@Zhaman ~]$ sudo virsh --connect xen:/// capabilities
> <capabilities>
> <host>
> <cpu>
> ....
> <topology>
> <cells num='2'>
> <cell id='0'>
> <memory unit='KiB'>6291456</memory>
> <cpus num='8'>
> <cpu id='0' socket_id='1' core_id='0' siblings='0-1'/>
> <cpu id='1' socket_id='1' core_id='0' siblings='0-1'/>
> <cpu id='2' socket_id='1' core_id='1' siblings='2-3'/>
> <cpu id='3' socket_id='1' core_id='1' siblings='2-3'/>
> <cpu id='4' socket_id='1' core_id='9' siblings='4-5'/>
> <cpu id='5' socket_id='1' core_id='9' siblings='4-5'/>
> <cpu id='6' socket_id='1' core_id='10' siblings='6-7'/>
> <cpu id='7' socket_id='1' core_id='10' siblings='6-7'/>
> </cpus>
> </cell>
> <cell id='1'>
> <memory unit='KiB'>6881280</memory>
> <cpus num='8'>
> <cpu id='8' socket_id='0' core_id='0' siblings='8-9'/>
> <cpu id='9' socket_id='0' core_id='0' siblings='8-9'/>
> <cpu id='10' socket_id='0' core_id='1' siblings='10-11'/>
> <cpu id='11' socket_id='0' core_id='1' siblings='10-11'/>
> <cpu id='12' socket_id='0' core_id='9' siblings='12-13'/>
> <cpu id='13' socket_id='0' core_id='9' siblings='12-13'/>
> <cpu id='14' socket_id='0' core_id='10' siblings='14-15'/>
> <cpu id='15' socket_id='0' core_id='10' siblings='14-15'/>
> </cpus>
> </cell>
> </cells>
> </topology>
> </host>
> ....
>
> Signed-off-by: Dario Faggioli <dario.faggioli@xxxxxxxxxx>
> Cc: Daniel P. Berrange <berrange@xxxxxxxxxx>
> ---
> Changes from v3:
> * updated VIR_*ALLOC* call sites not to invoke virReportOOMError();
> * failing at getting NUMA and CPU topology info from libxl are now
> considered proper errors, as requested during review;
> * s/out/cleanup/ as requested during review.
>
> Changes from v2:
> * iterators turned from int to size_t;
> * fixed wrong sibling maps if on same node but different socket;
> * code motion and error handling, as requested during review.
>
> Changes from v1:
> * fixed a typo in the commit message, as requested during review;
> * fixed coding style (one function parameters per line and no spaces
> between variable definitions), as requested during review;
> * avoid zero-filling memory after VIR_ALLOC_N(), since it does that
> already, as requested during review;
> * improved out of memory error reporting, as requested during review;
> * libxlMakeNumaCapabilities() created, accommodating all the NUMA
> related additions, instead of having them within
> libxlMakeCapabilitiesInternal(), as suggested during review.
> ---
> src/libxl/libxl_conf.c | 140 ++++++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 139 insertions(+), 1 deletion(-)
>
> diff --git a/src/libxl/libxl_conf.c b/src/libxl/libxl_conf.c
> index 827dfdd..2c84191 100644
> --- a/src/libxl/libxl_conf.c
> +++ b/src/libxl/libxl_conf.c
> @@ -161,6 +161,107 @@ libxlBuildCapabilities(virArch hostarch,
> }
>
> static virCapsPtr
> +libxlMakeNumaCapabilities(libxl_numainfo *numa_info,
> + int nr_nodes,
> + libxl_cputopology *cpu_topo,
> + int nr_cpus,
> + virCapsPtr caps)
>
I know we discussed returning an int from this function to indicate
success/failure, and that I agreed with your reasoning [1] to keep the
virCapsPtr. But now that driver init fails if gathering NUMA fails, I
think this really should return an int.
> +{
> + virCapsHostNUMACellCPUPtr *cpus = NULL;
> + int *nr_cpus_node = NULL;
> + bool numa_failed = true;
> + size_t i;
> +
> + if (VIR_ALLOC_N(cpus, nr_nodes) < 0)
> + goto cleanup;
> +
> + if (VIR_ALLOC_N(nr_cpus_node, nr_nodes) < 0)
> + goto cleanup;
> +
> + /* For each node, prepare a list of CPUs belonging to that node */
> + for (i = 0; i < nr_cpus; i++) {
> + int node = cpu_topo[i].node;
> +
> + if (cpu_topo[i].core == LIBXL_CPUTOPOLOGY_INVALID_ENTRY)
> + continue;
> +
> + nr_cpus_node[node]++;
> +
> + if (nr_cpus_node[node] == 1) {
> + if (VIR_ALLOC(cpus[node]) < 0)
> + goto cleanup;
> + } else {
> + if (VIR_REALLOC_N(cpus[node], nr_cpus_node[node]) < 0)
> + goto cleanup;
> + }
> +
> + /* Mapping between what libxl tells and what libvirt wants */
> + cpus[node][nr_cpus_node[node]-1].id = i;
> + cpus[node][nr_cpus_node[node]-1].socket_id = cpu_topo[i].socket;
> + cpus[node][nr_cpus_node[node]-1].core_id = cpu_topo[i].core;
> + /* Allocate the siblings maps. We will be filling them later */
> + cpus[node][nr_cpus_node[node]-1].siblings = virBitmapNew(nr_cpus);
> + if (!cpus[node][nr_cpus_node[node]-1].siblings) {
> + virReportOOMError();
> + goto cleanup;
> + }
> + }
> +
> + /* Let's now populate the siblings bitmaps */
> + for (i = 0; i < nr_cpus; i++) {
> + int node = cpu_topo[i].node;
> + size_t j;
> +
> + if (cpu_topo[i].core == LIBXL_CPUTOPOLOGY_INVALID_ENTRY)
> + continue;
> +
> + for (j = 0; j < nr_cpus_node[node]; j++) {
> + if (cpus[node][j].socket_id == cpu_topo[i].socket &&
> + cpus[node][j].core_id == cpu_topo[i].core)
> + ignore_value(virBitmapSetBit(cpus[node][j].siblings, i));
> + }
> + }
> +
> + for (i = 0; i < nr_nodes; i++) {
> + if (numa_info[i].size == LIBXL_NUMAINFO_INVALID_ENTRY)
> + continue;
> +
> + if (virCapabilitiesAddHostNUMACell(caps, i, nr_cpus_node[i],
> + numa_info[i].size / 1024,
> + cpus[i]) < 0) {
> + virCapabilitiesClearHostNUMACellCPUTopology(cpus[i],
> + nr_cpus_node[i]);
> + goto cleanup;
> + }
> +
> + /* This is safe, as the CPU list is now stored in the NUMA cell */
> + cpus[i] = NULL;
> + }
> +
> + numa_failed = false;
> +
> + cleanup:
> + if (numa_failed) {
> + /* Something went wrong: deallocate everything and unref caps */
> + virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
> + _("libxenlight failed to build the NUMA topology"));
> +
> + for (i = 0; i < nr_nodes; i++) {
> + VIR_FREE(cpus[i]);
> + }
> + virCapabilitiesFreeNUMAInfo(caps);
> +
> + if (!virObjectUnref(caps))
> + caps = NULL;
>
I'm not fond of unref'ing caps and setting to NULL here, outside of the
function where caps was allocated.
I sent a patch to rework the capabilities code [2], which I think will
make it a bit easier to implement this function. What do you think?
Regards,
Jim
[1] https://www.redhat.com/archives/libvir-list/2013-July/msg00458.html
[2] https://www.redhat.com/archives/libvir-list/2013-August/msg00543.html
> + }
> +
> + VIR_FREE(cpus);
> + VIR_FREE(nr_cpus_node);
> +
> + return caps;
> +}
> +
> +static virCapsPtr
> libxlMakeCapabilitiesInternal(virArch hostarch,
> libxl_physinfo *phy_info,
> char *capabilities)
> @@ -876,7 +977,11 @@ libxlMakeCapabilities(libxl_ctx *ctx)
> {
> int err;
> libxl_physinfo phy_info;
> + libxl_numainfo *numa_info = NULL;
> + libxl_cputopology *cpu_topo = NULL;
> const libxl_version_info *ver_info;
> + int nr_nodes = 0, nr_cpus = 0;
> + virCapsPtr caps;
>
> err = regcomp(&xen_cap_rec, xen_cap_re, REG_EXTENDED);
> if (err != 0) {
> @@ -900,9 +1005,42 @@ libxlMakeCapabilities(libxl_ctx *ctx)
> return NULL;
> }
>
> - return libxlMakeCapabilitiesInternal(virArchFromHost(),
> + caps = libxlMakeCapabilitiesInternal(virArchFromHost(),
> &phy_info,
> ver_info->capabilities);
> +
> + /* Check if caps is valid. If it is, it must remain so till the end! */
> + if (caps == NULL)
> + goto cleanup;
> +
> + /* Let's try to fetch all the topology information */
> + numa_info = libxl_get_numainfo(ctx, &nr_nodes);
> + if (numa_info == NULL || nr_nodes == 0) {
> + virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
> + _("libxl_get_numainfo failed"));
> + goto cleanup;
> + } else {
> + cpu_topo = libxl_get_cpu_topology(ctx, &nr_cpus);
> + if (cpu_topo == NULL || nr_cpus == 0) {
> + virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
> + _("libxl_get_cpu_topology failed"));
> + goto cleanup;
> + }
> + else {
> + /* And add topology information to caps */
> + caps = libxlMakeNumaCapabilities(numa_info,
> + nr_nodes,
> + cpu_topo,
> + nr_cpus,
> + caps);
> + }
> + }
> +
> +cleanup:
> + libxl_cputopology_list_free(cpu_topo, nr_cpus);
> + libxl_numainfo_list_free(numa_info, nr_nodes);
> +
> + return caps;
> }
>
> int
>
>
>
>
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