[Xen-devel] [PATCH RESEND 02/12] xl: allow for node-wise specification of vcpu pinning

[Dario Faggioli <dario.faggioli@xxxxxxxxxx>]

Making it possible to use something like the following:
 * "nodes:0-3": all pCPUs of nodes 0,1,2,3;
 * "nodes:0-3,^node:2": all pCPUS of nodes 0,1,3;
 * "1,nodes:1-2,^6": pCPU 1 plus all pCPUs of nodes 1,2
   but not pCPU 6;
 * ...

In both domain config file and `xl vcpu-pin'.

Signed-off-by: Dario Faggioli <dario.faggioli@xxxxxxxxxx>
---
Picking this up from a previously submitted series ("xl:
allow for node-wise specification of vcpu pinning") as the
changes in that and in this series would otherwise be
conflicting. If this is considered fine, Feel free to apply
it from here and skip the corresponding e-mail in the
original submission.
---
Changes from v2:
 * turned a 'return' into 'goto out', consistently with the
   most of exit patterns;
 * harmonized error handling: now parse_range() return a
   libxl error code, as requested during review;
 * dealing with "all" moved inside update_cpumap_range().
   It's tricky to move it in parse_range() (as requested
   during review), since we need the cpumap being modified
   handy when dealing with it. However, having it in
   update_cpumap_range() simplifies the code just as much
   as that;
 * explicitly checking for junk after a valid value or range
   in parse_range(), as requested during review;
 * xl exits on parsing failing, so no need to reset the
   cpumap to something sensible in vcpupin_parse(), as
   suggested during review;

Changes from v1:
 * code rearranged in order to look more simple to follow
   and understand, as requested during review;
 * improved docs in xl.cfg.pod.5, as requested during
   review;
 * strtoul() now returns into unsigned long, and the
   case where it returns ULONG_MAX is now taken into
   account, as requested during review;
 * stuff like "all,^7" now works, as requested during
   review. Specifying just "^7" does not work either
   before or after this change
 * killed some magic (i.e., `ptr += 5 + (ptr[4] == 's'`)
   by introducing STR_SKIP_PREFIX() macro, as requested
   during review.
---
 docs/man/xl.cfg.pod.5    |   20 ++++++
 tools/libxl/xl_cmdimpl.c |  145 ++++++++++++++++++++++++++++++++--------------
 2 files changed, 121 insertions(+), 44 deletions(-)

diff --git a/docs/man/xl.cfg.pod.5 b/docs/man/xl.cfg.pod.5
index d2d8921..1c98cb4 100644
--- a/docs/man/xl.cfg.pod.5
+++ b/docs/man/xl.cfg.pod.5
@@ -115,7 +115,25 @@ To allow all the vcpus of the guest to run on all the cpus 
on the host.
 
 =item "0-3,5,^1"
 
-To allow all the vcpus of the guest to run on cpus 0,2,3,5.
+To allow all the vcpus of the guest to run on cpus 0,2,3,5. Combining
+this with "all" is possible, meaning "all,^7" results in all the vcpus
+of the guest running on all the cpus on the host except cpu 7.
+
+=item "nodes:0-3,node:^2"
+
+To allow all the vcpus of the guest to run on the cpus from NUMA nodes
+0,1,3 of the host. So, if cpus 0-3 belongs to node 0, cpus 4-7 belongs
+to node 1 and cpus 8-11 to node 3, the above would mean all the vcpus
+of the guest will run on cpus 0-3,8-11.
+
+Combining this notation with the one above is possible. For instance,
+"1,node:2,^6", means all the vcpus of the guest will run on cpu 1 and
+on all the cpus of NUMA node 2, but not on cpu 6. Following the same
+example as above, that would be cpus 1,4,5,7.
+
+Combining this with "all" is also possible, meaning "all,^nodes:1"
+results in all the vcpus of the guest running on all the cpus on the
+host, except for the cpus belonging to the host NUMA node 1.
 
 =item ["2", "3"] (or [2, 3])
 
diff --git a/tools/libxl/xl_cmdimpl.c b/tools/libxl/xl_cmdimpl.c
index 40feb7d..b8755b9 100644
--- a/tools/libxl/xl_cmdimpl.c
+++ b/tools/libxl/xl_cmdimpl.c
@@ -59,6 +59,11 @@
         }                                                               \
     })
 
+#define STR_HAS_PREFIX( a, b )  \
+    ( strncmp(a, b, strlen(b)) == 0 )
+#define STR_SKIP_PREFIX( a, b ) \
+    ( STR_HAS_PREFIX(a, b) ? (a) += strlen(b) : NULL )
+
 
 int logfile = 2;
 
@@ -513,61 +518,115 @@ static void split_string_into_string_list(const char 
*str,
     free(s);
 }
 
-static int vcpupin_parse(char *cpu, libxl_bitmap *cpumap)
+static int parse_range(const char *str, unsigned long *a, unsigned long *b)
+{
+    char *nstr, *endptr;
+
+    *a = *b = strtoul(str, &endptr, 10);
+    if (endptr == str || *a == ULONG_MAX)
+        return ERROR_INVAL;
+
+    if (*endptr == '-') {
+        nstr = endptr + 1;
+
+        *b = strtoul(nstr, &endptr, 10);
+        if (endptr == nstr || *b == ULONG_MAX || *b < *a)
+            return ERROR_INVAL;
+    }
+
+    /* Valid value or range so far, but we also don't want junk after that */
+    if (*endptr != '\0')
+        return ERROR_INVAL;
+
+    return 0;
+}
+
+/*
+ * Add or removes a specific set of cpus (specified in str, either as
+ * single cpus or as entire NUMA nodes) to/from cpumap.
+ */
+static int update_cpumap_range(const char *str, libxl_bitmap *cpumap)
 {
-    libxl_bitmap exclude_cpumap;
-    uint32_t cpuida, cpuidb;
-    char *endptr, *toka, *tokb, *saveptr = NULL;
-    int i, rc = 0, rmcpu;
+    unsigned long ida, idb;
+    libxl_bitmap node_cpumap;
+    bool is_not = false, is_nodes = false;
+    int rc = 0;
+
+    libxl_bitmap_init(&node_cpumap);
 
-    if (!strcmp(cpu, "all")) {
+    rc = libxl_node_bitmap_alloc(ctx, &node_cpumap, 0);
+    if (rc) {
+        fprintf(stderr, "libxl_node_bitmap_alloc failed.\n");
+        goto out;
+    }
+
+    /* Are we adding or removing cpus/nodes? */
+    if (STR_SKIP_PREFIX(str, "^")) {
+        is_not = true;
+    }
+
+    /* Are we dealing with cpus or full nodes? */
+    if (STR_SKIP_PREFIX(str, "nodes:")) {
+        is_nodes = true;
+    }
+
+    if (STR_HAS_PREFIX(str, "all")) {
         libxl_bitmap_set_any(cpumap);
-        return 0;
+        goto out;
     }
 
-    if (libxl_cpu_bitmap_alloc(ctx, &exclude_cpumap, 0)) {
-        fprintf(stderr, "Error: Failed to allocate cpumap.\n");
-        return ENOMEM;
+    rc = parse_range(str, &ida, &idb);
+    if (rc) {
+        fprintf(stderr, "Invalid pcpu range: %s.\n", str);
+        goto out;
     }
 
-    for (toka = strtok_r(cpu, ",", &saveptr); toka;
-         toka = strtok_r(NULL, ",", &saveptr)) {
-        rmcpu = 0;
-        if (*toka == '^') {
-            /* This (These) Cpu(s) will be removed from the map */
-            toka++;
-            rmcpu = 1;
-        }
-        /* Extract a valid (range of) cpu(s) */
-        cpuida = cpuidb = strtoul(toka, &endptr, 10);
-        if (endptr == toka) {
-            fprintf(stderr, "Error: Invalid argument.\n");
-            rc = EINVAL;
-            goto vcpp_out;
-        }
-        if (*endptr == '-') {
-            tokb = endptr + 1;
-            cpuidb = strtoul(tokb, &endptr, 10);
-            if (endptr == tokb || cpuida > cpuidb) {
-                fprintf(stderr, "Error: Invalid argument.\n");
-                rc = EINVAL;
-                goto vcpp_out;
+    /* Add or remove the specified cpus in the range */
+    while (ida <= idb) {
+        if (is_nodes) {
+            /* Add/Remove all the cpus of a NUMA node */
+            int i;
+
+            rc = libxl_node_to_cpumap(ctx, ida, &node_cpumap);
+            if (rc) {
+                fprintf(stderr, "libxl_node_to_cpumap failed.\n");
+                goto out;
             }
+
+            /* Add/Remove all the cpus in the node cpumap */
+            libxl_for_each_set_bit(i, node_cpumap) {
+                is_not ? libxl_bitmap_reset(cpumap, i) :
+                         libxl_bitmap_set(cpumap, i);
+            }
+        } else {
+            /* Add/Remove this cpu */
+            is_not ? libxl_bitmap_reset(cpumap, ida) :
+                     libxl_bitmap_set(cpumap, ida);
         }
-        while (cpuida <= cpuidb) {
-            rmcpu == 0 ? libxl_bitmap_set(cpumap, cpuida) :
-                         libxl_bitmap_set(&exclude_cpumap, cpuida);
-            cpuida++;
-        }
+        ida++;
     }
 
-    /* Clear all the cpus from the removal list */
-    libxl_for_each_set_bit(i, exclude_cpumap) {
-        libxl_bitmap_reset(cpumap, i);
-    }
+ out:
+    libxl_bitmap_dispose(&node_cpumap);
+    return rc;
+}
+
+/*
+ * Takes a string representing a set of cpus (specified either as
+ * single cpus or as eintire NUMA nodes) and turns it into the
+ * corresponding libxl_bitmap (in cpumap).
+ */
+static int vcpupin_parse(char *cpu, libxl_bitmap *cpumap)
+{
+    char *ptr, *saveptr = NULL;
+    int rc = 0;
 
-vcpp_out:
-    libxl_bitmap_dispose(&exclude_cpumap);
+    for (ptr = strtok_r(cpu, ",", &saveptr); ptr;
+         ptr = strtok_r(NULL, ",", &saveptr)) {
+        rc = update_cpumap_range(ptr, cpumap);
+        if (rc)
+            break;
+    }
 
     return rc;
 }


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