| Message ID | 1456174934-22973-6-git-send-email-joao.m.martins@oracle.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Mon, Feb 22, 2016 at 09:02:11PM +0000, Joao Martins wrote: > By setting it to true, it enables the vcpus set by the guest > to be seen as a SMT-enabled topology. It uses then > libxl__cpuid_set_topology() to change the cpuid accordingly. > This setting is made *before* the cpuid is set so that > any changes could be overwritten. The number of SMT threads > are the ones supported by the host. And for that it adds > another helper routine libxl__count_threads_per_core to fetch > it. > > This feature is useful in HT-enabled hosts so that hard > pinned domains can see the right topology (i.e. SMT cores exposed > as SMT cores) which in return would lead guest scheduler making > better decisions. > I think we need more sophisticated configuration options then just a bool. If we're doing this, there is no reason why we shouldn't allow administrator to set arbitrary topology for the guest. Wei.
diff --git a/tools/libxl/libxl_create.c b/tools/libxl/libxl_create.c index de5d27f..dac15d5 100644 --- a/tools/libxl/libxl_create.c +++ b/tools/libxl/libxl_create.c @@ -195,6 +195,8 @@ int libxl__domain_build_info_setdefault(libxl__gc *gc, b_info->num_vcpu_hard_affinity = b_info->max_vcpus; } + libxl_defbool_setdefault(&b_info->smt, false); + libxl_defbool_setdefault(&b_info->numa_placement, true); if (b_info->max_memkb == LIBXL_MEMKB_DEFAULT) diff --git a/tools/libxl/libxl_dom.c b/tools/libxl/libxl_dom.c index 2269998..ff9356d 100644 --- a/tools/libxl/libxl_dom.c +++ b/tools/libxl/libxl_dom.c @@ -507,6 +507,16 @@ int libxl__build_post(libxl__gc *gc, uint32_t domid, } libxl_cpuid_apply_policy(ctx, domid); + if (info->type == LIBXL_DOMAIN_TYPE_HVM + && libxl_defbool_val(info->smt)) { + + uint32_t threads = 0; + + if (!libxl__count_threads_per_core(gc, &threads)) + libxl__cpuid_set_topology(ctx, domid, + info->max_vcpus / threads, threads); + } + if (info->cpuid != NULL) libxl_cpuid_set(ctx, domid, info->cpuid); diff --git a/tools/libxl/libxl_internal.h b/tools/libxl/libxl_internal.h index 903ad7b..7cc4de7 100644 --- a/tools/libxl/libxl_internal.h +++ b/tools/libxl/libxl_internal.h @@ -4033,6 +4033,7 @@ void libxl__bitmap_copy_best_effort(libxl__gc *gc, libxl_bitmap *dptr, const libxl_bitmap *sptr); int libxl__count_physical_sockets(libxl__gc *gc, int *sockets); +int libxl__count_threads_per_core(libxl__gc *gc, uint32_t *threads); #define LIBXL_QEMU_USER_PREFIX "xen-qemuuser" diff --git a/tools/libxl/libxl_types.idl b/tools/libxl/libxl_types.idl index f04279e..fa4725a 100644 --- a/tools/libxl/libxl_types.idl +++ b/tools/libxl/libxl_types.idl @@ -421,6 +421,7 @@ libxl_domain_build_info = Struct("domain_build_info",[ ("nodemap", libxl_bitmap), ("vcpu_hard_affinity", Array(libxl_bitmap, "num_vcpu_hard_affinity")), ("vcpu_soft_affinity", Array(libxl_bitmap, "num_vcpu_soft_affinity")), + ("smt", libxl_defbool), ("numa_placement", libxl_defbool), ("tsc_mode", libxl_tsc_mode), ("max_memkb", MemKB), diff --git a/tools/libxl/libxl_utils.c b/tools/libxl/libxl_utils.c index e42422a..dd063c8 100644 --- a/tools/libxl/libxl_utils.c +++ b/tools/libxl/libxl_utils.c @@ -861,6 +861,23 @@ int libxl__count_physical_sockets(libxl__gc *gc, int *sockets) return 0; } +int libxl__count_threads_per_core(libxl__gc *gc, uint32_t *threads) +{ + int rc; + libxl_physinfo info; + + libxl_physinfo_init(&info); + + rc = libxl_get_physinfo(CTX, &info); + if (rc) + return rc; + + *threads = info.threads_per_core; + + libxl_physinfo_dispose(&info); + return 0; +} + int libxl_socket_bitmap_alloc(libxl_ctx *ctx, libxl_bitmap *socketmap, int max_sockets) {
By setting it to true, it enables the vcpus set by the guest to be seen as a SMT-enabled topology. It uses then libxl__cpuid_set_topology() to change the cpuid accordingly. This setting is made *before* the cpuid is set so that any changes could be overwritten. The number of SMT threads are the ones supported by the host. And for that it adds another helper routine libxl__count_threads_per_core to fetch it. This feature is useful in HT-enabled hosts so that hard pinned domains can see the right topology (i.e. SMT cores exposed as SMT cores) which in return would lead guest scheduler making better decisions. Signed-off-by: Joao Martins <joao.m.martins@oracle.com> --- CC: Ian Jackson <ian.jackson@eu.citrix.com> CC: Stefano Stabellini <stefano.stabellini@eu.citrix.com> CC: Ian Campbell <ian.campbell@citrix.com> CC: Wei Liu <wei.liu2@citrix.com> --- tools/libxl/libxl_create.c | 2 ++ tools/libxl/libxl_dom.c | 10 ++++++++++ tools/libxl/libxl_internal.h | 1 + tools/libxl/libxl_types.idl | 1 + tools/libxl/libxl_utils.c | 17 +++++++++++++++++ 5 files changed, 31 insertions(+)