[PATCH v4 1/7] libxl: get rid of the SEDF scheduler

[Dario Faggioli <dario.faggioli@citrix.com>]

only the interface is left in place, for backward
compile-time compatibility, but every attempt to
use it would throw an error.

Signed-off-by: Dario Faggioli <dario.faggioli@citrix.com>
---
Cc: George Dunlap <george.dunlap@eu.citrix.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>

Changes from v3:
 - drop George's Rev-by: which should not be there since v2;
 - better grouping of fields in libxl_domain_sched_params, as
   suggested during review;
 - improved comment for ERROR_FEATURE_REMOVED, as suggested
   during review.

Changes from v2:
 - introduce and use ERROR_FEATURE_REMOVED, as requested
   during review;
 - mark the SEDF only parameter as deprecated in libxl_types.idl,
   as requested during review.
---
 tools/libxl/libxl.c         |   73 ++-----------------------------------------
 tools/libxl/libxl_create.c  |   61 ------------------------------------
 tools/libxl/libxl_types.idl |    8 ++++-
 3 files changed, 11 insertions(+), 131 deletions(-)

diff --git a/tools/libxl/libxl.c b/tools/libxl/libxl.c
index 3a83903..38aff8d 100644
--- a/tools/libxl/libxl.c
+++ b/tools/libxl/libxl.c
@@ -5728,73 +5728,6 @@ static int sched_credit2_domain_set(libxl__gc *gc, uint32_t domid,
     return 0;
 }
 
-static int sched_sedf_domain_get(libxl__gc *gc, uint32_t domid,
-                                 libxl_domain_sched_params *scinfo)
-{
-    uint64_t period;
-    uint64_t slice;
-    uint64_t latency;
-    uint16_t extratime;
-    uint16_t weight;
-    int rc;
-
-    rc = xc_sedf_domain_get(CTX->xch, domid, &period, &slice, &latency,
-                            &extratime, &weight);
-    if (rc != 0) {
-        LOGE(ERROR, "getting domain sched sedf");
-        return ERROR_FAIL;
-    }
-
-    libxl_domain_sched_params_init(scinfo);
-    scinfo->sched = LIBXL_SCHEDULER_SEDF;
-    scinfo->period = period / 1000000;
-    scinfo->slice = slice / 1000000;
-    scinfo->latency = latency / 1000000;
-    scinfo->extratime = extratime;
-    scinfo->weight = weight;
-
-    return 0;
-}
-
-static int sched_sedf_domain_set(libxl__gc *gc, uint32_t domid,
-                                 const libxl_domain_sched_params *scinfo)
-{
-    uint64_t period;
-    uint64_t slice;
-    uint64_t latency;
-    uint16_t extratime;
-    uint16_t weight;
-
-    int ret;
-
-    ret = xc_sedf_domain_get(CTX->xch, domid, &period, &slice, &latency,
-                            &extratime, &weight);
-    if (ret != 0) {
-        LOGE(ERROR, "getting domain sched sedf");
-        return ERROR_FAIL;
-    }
-
-    if (scinfo->period != LIBXL_DOMAIN_SCHED_PARAM_PERIOD_DEFAULT)
-        period = (uint64_t)scinfo->period * 1000000;
-    if (scinfo->slice != LIBXL_DOMAIN_SCHED_PARAM_SLICE_DEFAULT)
-        slice = (uint64_t)scinfo->slice * 1000000;
-    if (scinfo->latency != LIBXL_DOMAIN_SCHED_PARAM_LATENCY_DEFAULT)
-        latency = (uint64_t)scinfo->latency * 1000000;
-    if (scinfo->extratime != LIBXL_DOMAIN_SCHED_PARAM_EXTRATIME_DEFAULT)
-        extratime = scinfo->extratime;
-    if (scinfo->weight != LIBXL_DOMAIN_SCHED_PARAM_WEIGHT_DEFAULT)
-        weight = scinfo->weight;
-
-    ret = xc_sedf_domain_set(CTX->xch, domid, period, slice, latency,
-                            extratime, weight);
-    if ( ret < 0 ) {
-        LOGE(ERROR, "setting domain sched sedf");
-        return ERROR_FAIL;
-    }
-
-    return 0;
-}
-
 static int sched_rtds_domain_get(libxl__gc *gc, uint32_t domid,
                                libxl_domain_sched_params *scinfo)
 {
@@ -5873,7 +5806,8 @@ int libxl_domain_sched_params_set(libxl_ctx *ctx, uint32_t domid,
 
     switch (sched) {
     case LIBXL_SCHEDULER_SEDF:
-        ret=sched_sedf_domain_set(gc, domid, scinfo);
+        LOG(ERROR, "SEDF scheduler no longer available");
+        ret=ERROR_FEATURE_REMOVED;
         break;
     case LIBXL_SCHEDULER_CREDIT:
         ret=sched_credit_domain_set(gc, domid, scinfo);
@@ -5909,7 +5843,8 @@ int libxl_domain_sched_params_get(libxl_ctx *ctx, uint32_t domid,
 
     switch (scinfo->sched) {
     case LIBXL_SCHEDULER_SEDF:
-        ret=sched_sedf_domain_get(gc, domid, scinfo);
+        LOG(ERROR, "SEDF scheduler no longer available");
+        ret=ERROR_FEATURE_REMOVED;
         break;
     case LIBXL_SCHEDULER_CREDIT:
         ret=sched_credit_domain_get(gc, domid, scinfo);
diff --git a/tools/libxl/libxl_create.c b/tools/libxl/libxl_create.c
index 9c2303c..3f31a3b 100644
--- a/tools/libxl/libxl_create.c
+++ b/tools/libxl/libxl_create.c
@@ -50,61 +50,6 @@ int libxl__domain_create_info_setdefault(libxl__gc *gc,
     return 0;
 }
 
-static int sched_params_valid(libxl__gc *gc,
-                              uint32_t domid, libxl_domain_sched_params *scp)
-{
-    int has_weight = scp->weight != LIBXL_DOMAIN_SCHED_PARAM_WEIGHT_DEFAULT;
-    int has_period = scp->period != LIBXL_DOMAIN_SCHED_PARAM_PERIOD_DEFAULT;
-    int has_slice = scp->slice != LIBXL_DOMAIN_SCHED_PARAM_SLICE_DEFAULT;
-    int has_extratime =
-                scp->extratime != LIBXL_DOMAIN_SCHED_PARAM_EXTRATIME_DEFAULT;
-
-    /* The sedf scheduler needs some more consistency checking */
-    if (libxl__domain_scheduler(gc, domid) == LIBXL_SCHEDULER_SEDF) {
-        if (has_weight && (has_period || has_slice))
-            return 0;
-        /* If you want a real-time domain, with its own period and
-         * slice, please, do provide both! */
-        if (has_period != has_slice)
-            return 0;
-
-        /*
-         * Idea is, if we specify a weight, then both period and
-         * slice has to be zero. OTOH, if we do specify a period and
-         * slice, it is weight that should be zeroed. See
-         * docs/misc/sedf_scheduler_mini-HOWTO.txt for more details
-         * on the meaningful combinations and their meanings.
-         */
-        if (has_weight) {
-            scp->slice = 0;
-            scp->period = 0;
-        }
-        else if (!has_period) {
-            /* No weight nor slice/period means best effort. Parameters needs
-             * some mangling in order to properly ask for that, though. */
-
-            /*
-             * Providing no weight does not make any sense if we do not allow
-             * the domain to run in extra time. On the other hand, if we have
-             * extra time, weight will be ignored (and zeroed) by Xen, but it
-             * can't be zero here, or the call for setting the scheduling
-             * parameters will fail. So, avoid the latter by setting a random
-             * weight (namely, 1), as it will be ignored anyway.
-             */
-
-            /* We can setup a proper best effort domain (extra time only)
-             * iff we either already have or are asking for some extra time. */
-            scp->weight = has_extratime ? scp->extratime : 1;
-            scp->period = 0;
-        } else {
-            /* Real-time domain: will get slice CPU time over every period */
-            scp->weight = 0;
-        }
-    }
-
-    return 1;
-}
-
 int libxl__domain_build_info_setdefault(libxl__gc *gc,
                                         libxl_domain_build_info *b_info)
 {
@@ -888,12 +833,6 @@ static void initiate_domain_create(libxl__egc *egc,
     ret = libxl__domain_build_info_setdefault(gc, &d_config->b_info);
     if (ret) goto error_out;
 
-    if (!sched_params_valid(gc, domid, &d_config->b_info.sched_params)) {
-        LOG(ERROR, "Invalid scheduling parameters\n");
-        ret = ERROR_INVAL;
-        goto error_out;
-    }
-
     for (i = 0; i < d_config->num_disks; i++) {
         ret = libxl__device_disk_setdefault(gc, &d_config->disks[i]);
         if (ret) goto error_out;
diff --git a/tools/libxl/libxl_types.idl b/tools/libxl/libxl_types.idl
index e1632fa..378d6e3 100644
--- a/tools/libxl/libxl_types.idl
+++ b/tools/libxl/libxl_types.idl
@@ -68,6 +68,7 @@ libxl_error = Enumeration("error", [
     (-22, "ABORTED"),
     (-23, "NOTFOUND"),
     (-24, "DOMAIN_DESTROYED"), # Target domain ceased to exist during op
+    (-25, "FEATURE_REMOVED"), # For functionality that has been removed
     ], value_namespace = "")
 
 libxl_domain_type = Enumeration("domain_type", [
@@ -356,10 +357,15 @@ libxl_domain_sched_params = Struct("domain_sched_params",[
     ("weight",       integer, {'init_val': 'LIBXL_DOMAIN_SCHED_PARAM_WEIGHT_DEFAULT'}),
     ("cap",          integer, {'init_val': 'LIBXL_DOMAIN_SCHED_PARAM_CAP_DEFAULT'}),
     ("period",       integer, {'init_val': 'LIBXL_DOMAIN_SCHED_PARAM_PERIOD_DEFAULT'}),
+    ("budget",       integer, {'init_val': 'LIBXL_DOMAIN_SCHED_PARAM_BUDGET_DEFAULT'}),
+
+    # The following three parameters ('slice', 'latency' and 'extratime') are deprecated,
+    # and will have no effect if used, since the SEDF scheduler has been removed.
+    # Note that 'period' was an SDF parameter too, but it is still effective as it is
+    # now used (together with 'budget') by the RTDS scheduler.
     ("slice",        integer, {'init_val': 'LIBXL_DOMAIN_SCHED_PARAM_SLICE_DEFAULT'}),
     ("latency",      integer, {'init_val': 'LIBXL_DOMAIN_SCHED_PARAM_LATENCY_DEFAULT'}),
     ("extratime",    integer, {'init_val': 'LIBXL_DOMAIN_SCHED_PARAM_EXTRATIME_DEFAULT'}),
-    ("budget",       integer, {'init_val': 'LIBXL_DOMAIN_SCHED_PARAM_BUDGET_DEFAULT'}),
     ])
 
 libxl_vnode_info = Struct("vnode_info", [