[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH 13/13] tools/libxl: Add 'vtsc_khz' option to set guest TSC rate
On Mon, Sep 28, 2015 at 03:19:25PM +0100, Wei Liu wrote: > On Mon, Sep 28, 2015 at 03:13:58PM +0800, Haozhong Zhang wrote: > > This patch adds an option 'vtsc_khz' to allow users to set vcpu's TSC > > rate in KHz. In the case that tsc_mode = 'default', the default value of > > 'vtsc_khz' option is the host TSC rate which is used when 'vtsc_khz' > > option is set to 0 or does not appear in the configuration. In all other > > cases of tsc_mode, 'vtsc_khz' option is just ignored. > > > > Another purpose of adding this option is to keep vcpu's TSC rate across > > guest reboot. In existing code, a new domain is created from the > > configuration of the previous domain which was just rebooted. vcpu's TSC > > rate is not stored in the configuration and the host TSC rate is the > > used as vcpu's TSC rate. This works fine unless the previous domain was > > migrated from another host machine with a different host TSC rate than > > the current one. > > > > Signed-off-by: Haozhong Zhang <haozhong.zhang@xxxxxxxxx> > > --- > > tools/libxl/libxl_types.idl | 1 + > > tools/libxl/libxl_x86.c | 4 +++- > > tools/libxl/xl_cmdimpl.c | 22 ++++++++++++++++++++++ > > 3 files changed, 26 insertions(+), 1 deletion(-) > > > > diff --git a/tools/libxl/libxl_types.idl b/tools/libxl/libxl_types.idl > > index 9f6ec00..91cb0be 100644 > > --- a/tools/libxl/libxl_types.idl > > +++ b/tools/libxl/libxl_types.idl > > @@ -413,6 +413,7 @@ libxl_domain_build_info = Struct("domain_build_info",[ > > ("vcpu_soft_affinity", Array(libxl_bitmap, "num_vcpu_soft_affinity")), > > ("numa_placement", libxl_defbool), > > ("tsc_mode", libxl_tsc_mode), > > + ("vtsc_khz", uint32), > > This field should be in arch-specific substructure, i.e. "hvm". > Julien also pointed out this and suggested to moving to an arch-specific substructure. I'm going to add a new substructure "arch_x86" and move "vtsc_khz" there. Is this good for you? > > ("max_memkb", MemKB), > > ("target_memkb", MemKB), > > ("video_memkb", MemKB), > > diff --git a/tools/libxl/libxl_x86.c b/tools/libxl/libxl_x86.c > > index 896f34c..7baaee4 100644 > > --- a/tools/libxl/libxl_x86.c > > +++ b/tools/libxl/libxl_x86.c > > @@ -276,6 +276,7 @@ int libxl__arch_domain_create(libxl__gc *gc, > > libxl_domain_config *d_config, > > { > > int ret = 0; > > int tsc_mode; > > + uint32_t vtsc_khz; > > uint32_t rtc_timeoffset; > > libxl_ctx *ctx = libxl__gc_owner(gc); > > > > @@ -300,7 +301,8 @@ int libxl__arch_domain_create(libxl__gc *gc, > > libxl_domain_config *d_config, > > default: > > abort(); > > } > > - xc_domain_set_tsc_info(ctx->xch, domid, tsc_mode, 0, 0, 0); > > + vtsc_khz = d_config->b_info.vtsc_khz; > > + xc_domain_set_tsc_info(ctx->xch, domid, tsc_mode, 0, vtsc_khz, 0); > > if (libxl_defbool_val(d_config->b_info.disable_migrate)) > > xc_domain_disable_migrate(ctx->xch, domid); > > rtc_timeoffset = d_config->b_info.rtc_timeoffset; > > diff --git a/tools/libxl/xl_cmdimpl.c b/tools/libxl/xl_cmdimpl.c > > index 2706759..5fabda7 100644 > > --- a/tools/libxl/xl_cmdimpl.c > > +++ b/tools/libxl/xl_cmdimpl.c > > @@ -1462,6 +1462,28 @@ static void parse_config_data(const char > > *config_source, > > } > > } > > > > + /* "vtsc_khz" option works only if "tsc_mode" option is > > + * "default". In this case, if "vtsc_khz" option is set to 0, we > > + * will reset it to the host TSC rate. In all other cases, we just > > + * ignore any given value and always set it to 0. > > + */ > > + if (!xlu_cfg_get_long(config, "vtsc_khz", &l, 0)) > > + b_info->vtsc_khz = l; > > + if (b_info->tsc_mode == LIBXL_TSC_MODE_DEFAULT) { > > + if (b_info->vtsc_khz == 0) { > > + libxl_physinfo physinfo; > > + if (!libxl_get_physinfo(ctx, &physinfo)) > > + b_info->vtsc_khz = physinfo.cpu_khz; > > + else > > + fprintf(stderr, "WARNING: cannot get host TSC rate.\n"); > > + } > > And this hunk (the decision making bit) should be in libxl, not xl. > > Consider there are other toolstack that uses libxl, say libvirt. > Good to know this. I'm going to move it to libxl__arch_domain_create() where b_info->vtsc_khz is used. Haozhong > Please ask if you have doubts. > > Wei. > > > + } else { > > + fprintf(stderr, "WARNING: ignoring \"vtsc_khz\" option. " > > + "\"vtsc_khz\" option works only if " > > + "\"tsc_mode\" option is \"default\".\n"); > > + b_info->vtsc_khz = 0; > > + } > > + > > > if (!xlu_cfg_get_long(config, "rtc_timeoffset", &l, 0)) > > b_info->rtc_timeoffset = l; > > > > -- > > 2.4.8 _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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