[Xen-devel] [PATCH v3 3/3] xentrace: Implement cpu mask range parsing of human values (-c).

[Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>]

Instead of just using -c 0x<some hex value> we can
also use -c <starting cpu>-<end cpu> or -c <cpu1>,<cpu2>
or a combination of them. Also it can include just
singular CPUs: -c <cpu1>, or ranges without an
start or end (and xentrace will figure out the values), such
as: -c -<cpu2> (which will include cpu0, cpu1, and cpu2) or
-c <cpu2>- (which will include cpu2 and up to MAX_CPUS).

That should make it easier to trace the right CPU if
using this along with 'xl vcpu-list'.

The code has been lifted from the Linux kernel, see file
lib/bitmap.c, function __bitmap_parselist.

To make the old behavior and the new function work, we check
to see if the arguments have '0x' in them. If they do
we use the old style parsing (limited to 32 CPUs). If that
does not exist we use the new parsing.

Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
[v4: Fix per George's review]
---
 tools/xentrace/xentrace.8 |  34 ++++++++-
 tools/xentrace/xentrace.c | 190 ++++++++++++++++++++++++++++++++++++++--------
 2 files changed, 188 insertions(+), 36 deletions(-)

diff --git a/tools/xentrace/xentrace.8 b/tools/xentrace/xentrace.8
index c176a96..eb6fba8 100644
--- a/tools/xentrace/xentrace.8
+++ b/tools/xentrace/xentrace.8
@@ -36,10 +36,36 @@ all new records to the output
 set the time, p, (in milliseconds) to sleep between polling the buffers
 for new data.
 .TP
-.B -c, --cpu-mask=c
-set bitmask of CPUs to trace. It is limited to 32-bits.
-If not specified, the cpu-mask of all of the available CPUs will be
-constructed.
+.B -c, --cpu-mask=[\fIc\fP|\fICPU-LIST\fP]
+This can either be a hex value (of the form 0xNNNN...), or a set of cpu
+ranges as described below. Hex values are limited to 32 bits. If not
+specified, the cpu-mask of all of the available CPUs will be
+constructed. If using the \fICPU-LIST\fP it expects decimal numbers, which
+may be specified as follows:
+
+.RS 4
+.ie n .IP """0-3""" 4
+.el .IP "``0-3''" 4
+.IX Item "0-3"
+Trace only on CPUs 0 through 3
+.ie n .IP """0,2,5-7""" 4
+.el .IP "``0,2,5-7''" 4
+.IX Item "0,2,5-7"
+Trace only on CPUs 0, 2, and 5 through 7.
+.ie n .IP """-3""" 4
+.el .IP "``-3''" 4
+.IX Item "-3"
+Trace only on CPUs 0 through 3
+.ie n .IP """-3,7""" 4
+.el .IP "``-3,7''" 4
+.IX Item "-3,7"
+Trace only on CPUs 0 through 3 and 7
+.ie n .IP """3-""" 4
+.el .IP "``3-''" 4
+.IX Item "-3-"
+Trace only on CPUs 3 up to maximum numbers of CPUs the host has.
+.RE
+.Sp
 
 .TP
 .B -e, --evt-mask=e
diff --git a/tools/xentrace/xentrace.c b/tools/xentrace/xentrace.c
index 40504ec..3dd5c01 100644
--- a/tools/xentrace/xentrace.c
+++ b/tools/xentrace/xentrace.c
@@ -23,6 +23,7 @@
 #include <string.h>
 #include <getopt.h>
 #include <assert.h>
+#include <ctype.h>
 #include <sys/poll.h>
 #include <sys/statvfs.h>
 
@@ -54,6 +55,7 @@ typedef struct settings_st {
     uint32_t evt_mask;
     xc_cpumap_t cpu_mask;
     int cpu_bits;
+    char *cpu_mask_str;
     unsigned long tbuf_size;
     unsigned long disk_rsvd;
     unsigned long timeout;
@@ -545,25 +547,6 @@ void print_cpu_mask(xc_cpumap_t mask, int bits)
 
 static void set_cpu_mask(xc_cpumap_t mask, int bits)
 {
-    int i;
-
-    if ( bits <= 0 )
-    {
-        bits = xc_get_max_cpus(xc_handle);
-        if ( bits <= 0 )
-            goto out;
-    }
-    if ( !mask )
-    {
-        mask = xc_cpumap_alloc(xc_handle);
-        if ( !mask )
-            goto out;
-
-        /* Set it to include _all_ CPUs. */
-        for ( i = 0; i < XC_DIV_ROUND_UP(bits, 8); i++ )
-            mask[i] = 0xff;
-    }
-    /* And this will limit it to the exact amount of bits. */
     if ( xc_tbuf_set_cpu_mask(xc_handle, mask, bits) )
         goto out;
 
@@ -822,7 +805,7 @@ static void usage(void)
 "Usage: xentrace [OPTION...] [output file]\n" \
 "Tool to capture Xen trace buffer data\n" \
 "\n" \
-"  -c, --cpu-mask=c        Set cpu-mask\n" \
+"  -c, --cpu-mask=c        Set cpu-mask, using either hex or CPU ranges\n" \
 "  -e, --evt-mask=e        Set evt-mask\n" \
 "  -s, --poll-sleep=p      Set sleep time, p, in milliseconds between\n" \
 "                          polling the trace buffer for new data\n" \
@@ -976,6 +959,156 @@ static int parse_cpumask(const char *arg)
     return 0;
 }
 
+#define ZERO_DIGIT '0'
+
+static int parse_cpumask_range(const char *arg)
+{
+    xc_cpumap_t map;
+    unsigned int a, b, buflen = strlen(arg);
+    int c, c_old, totaldigits, nmaskbits;
+    int in_range;
+    const char *s;
+
+    if ( !buflen )
+    {
+        fprintf(stderr, "Invalid option argument: %s\n", arg);
+        errno = EINVAL;
+        return EXIT_FAILURE;
+    }
+    nmaskbits = xc_get_max_cpus(xc_handle);
+    if ( nmaskbits <= 0 )
+    {
+        fprintf(stderr, "Failed to get max number of CPUs! rc: %d\n", 
nmaskbits);
+        return EXIT_FAILURE;
+    }
+    map = xc_cpumap_alloc(xc_handle);
+    if ( !map )
+    {
+        fprintf(stderr, "Out of memory!\n");
+        return EXIT_FAILURE;
+    }
+    c = c_old = totaldigits = 0;
+    s = arg;
+    do {
+        in_range = 0;
+        a = b = 0;
+        /* The buflen can become zero in the '} while(..) below. */
+        while ( buflen )
+        {
+            c_old = c;
+            c = *s++;
+            buflen--;
+
+            if ( isspace(c) )
+                continue;
+
+            if ( totaldigits && c && isspace(c_old) )
+            {
+                fprintf(stderr, "No embedded whitespaces allowed in: %s\n", 
arg);
+                goto err_out;
+            }
+
+            /* A '\0' or a ',' signal the end of a cpu# or range */
+            if ( c == '\0' || c == ',' )
+                break;
+
+            if ( c == '-' )
+            {
+                if ( in_range )
+                        goto err_out;
+                b = 0;
+                in_range = 1;
+                continue;
+            }
+            if ( !isdigit(c) )
+            {
+                fprintf(stderr, "Only digits allowed in: %s\n", arg);
+                goto err_out;
+            }
+            b = b * 10 + (c - ZERO_DIGIT);
+            if ( !in_range )
+                a = b;
+            totaldigits++;
+        }
+        /* Syntax: <digit>-[,] - expand to number of CPUs. */
+        if ( b == 0 && in_range && (c == '-' || c == ',') )
+            b = nmaskbits-1;
+
+        if ( !(a <= b) )
+        {
+            fprintf(stderr, "Wrong order of %d and %d\n", a, b);
+            goto err_out;
+        }
+        if ( b >= nmaskbits )
+        {
+            fprintf(stderr, "Specified higher value then there are CPUS!\n");
+            goto err_out;
+        }
+        while ( a <= b )
+        {
+            xc_cpumap_setcpu(a, map);
+            a++;
+        }
+    } while ( buflen && c == ',' );
+
+    opts.cpu_mask = map;
+    opts.cpu_bits = nmaskbits;
+    return 0;
+ err_out:
+    free(map);
+    errno = EINVAL;
+    return EXIT_FAILURE;
+}
+
+/**
+ * Figure out which of the CPU types the user has provided - either the hex
+ * variant or the cpu-list. Once done set the CPU mask.
+ */
+static int figure_cpu_mask(void)
+{
+    int ret = EXIT_FAILURE;
+
+    if ( opts.cpu_mask_str )
+    {
+        if ( strlen(opts.cpu_mask_str) < 1 )
+        {
+            errno = ENOSPC;
+            goto out;
+        }
+        if ( strncmp("0x", opts.cpu_mask_str, 2) == 0 )
+            ret = parse_cpumask(opts.cpu_mask_str);
+        else
+            ret = parse_cpumask_range(opts.cpu_mask_str);
+    }
+    else
+    {
+        int i, bits;
+        xc_cpumap_t mask;
+
+        bits = xc_get_max_cpus(xc_handle);
+        if ( bits <= 0 )
+            goto out;
+
+        mask = xc_cpumap_alloc(xc_handle);
+        if ( !mask )
+            goto out;
+
+        /* Set it to include _all_ CPUs. */
+        for ( i = 0; i < XC_DIV_ROUND_UP(bits, 8); i++ )
+            mask[i] = 0xff;
+
+        opts.cpu_mask = mask;
+        opts.cpu_bits = bits;
+        ret = 0;
+    }
+    if ( ret != EXIT_FAILURE )
+        set_cpu_mask(opts.cpu_mask, opts.cpu_bits);
+ out:
+    /* We don't use it pass this point. */
+    free(opts.cpu_mask_str);
+    return ret;
+}
+
 /* parse command line arguments */
 static void parse_args(int argc, char **argv)
 {
@@ -1006,15 +1139,9 @@ static void parse_args(int argc, char **argv)
             opts.poll_sleep = argtol(optarg, 0);
             break;
 
-        case 'c': /* set new cpu mask for filtering*/
-            /* Set opts.cpu_mask later as we don't have 'xch' set yet. */
-            if ( parse_cpumask(optarg) )
-            {
-                perror("Not enough memory!");
-                exit(EXIT_FAILURE);
-            }
+        case 'c': /* set new cpu mask for filtering (when xch is set). */
+            opts.cpu_mask_str = strdup(optarg);
             break;
-        
         case 'e': /* set new event mask for filtering*/
             parse_evtmask(optarg);
             break;
@@ -1079,6 +1206,7 @@ int main(int argc, char **argv)
     opts.evt_mask = 0;
     opts.cpu_mask = NULL;
     opts.cpu_bits = 0;
+    opts.cpu_mask_str = NULL;
     opts.disk_rsvd = 0;
     opts.disable_tracing = 1;
     opts.start_disabled = 0;
@@ -1096,10 +1224,8 @@ int main(int argc, char **argv)
     if ( opts.evt_mask != 0 )
         set_evt_mask(opts.evt_mask);
 
-
-    set_cpu_mask(opts.cpu_mask, opts.cpu_bits);
-    /* We don't use it pass this point. */
-    free(opts.cpu_mask);
+    if (figure_cpu_mask())
+        usage(); /* calls exit. */
 
     if ( opts.timeout != 0 ) 
         alarm(opts.timeout);
-- 
2.1.0


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