On 2025-03-13 10:09, Bruce Richardson wrote:
On Wed, Mar 12, 2025 at 12:28:32PM -0700, Andre Muezerie wrote:
It's common to use %' in the printf format specifier to make large numbers
more easily readable by having the thousands grouped. However, this
grouping does not work on Windows. Therefore, a function is needed to make
uint64_t numbers more easily readable. There are at least two tests that
can benefit from this new function.
Signed-off-by: Andre Muezerie <andre...@linux.microsoft.com>
---
Thanks Andre, comments inline below.
/Bruce
lib/eal/common/eal_common_string_fns.c | 44 ++++++++++++++++++++++++++
lib/eal/include/rte_common.h | 31 ++++++++++++++++++
lib/eal/version.map | 3 ++
3 files changed, 78 insertions(+)
diff --git a/lib/eal/common/eal_common_string_fns.c
b/lib/eal/common/eal_common_string_fns.c
index 9ca2045b18..4cc7f35652 100644
--- a/lib/eal/common/eal_common_string_fns.c
+++ b/lib/eal/common/eal_common_string_fns.c
@@ -4,6 +4,7 @@
#include <ctype.h>
#include <errno.h>
+#include <inttypes.h>
#include <stdio.h>
#include <stdlib.h>
@@ -87,6 +88,12 @@ rte_str_to_size(const char *str)
endptr++; /* allow 1 space gap */
switch (*endptr) {
+ case 'E': case 'e':
+ size *= 1024; /* fall-through */
+ case 'P': case 'p':
+ size *= 1024; /* fall-through */
+ case 'T': case 't':
+ size *= 1024; /* fall-through */
case 'G': case 'g':
size *= 1024; /* fall-through */
case 'M': case 'm':
@@ -98,3 +105,40 @@ rte_str_to_size(const char *str)
}
return size;
}
+
+int
+rte_size_to_str(char *buf, int buf_size,
+ uint64_t count, bool use_iec)
Minor nit, I don't think you should need to wrap this, we can have lines up
to 100 chars long.
+{
+ const char *prefix = "kMGTPE";
Why is "k" in lower case compared to the others all in upper-case?
That's how International Bureau of Weights and Measures likes it,
although they keep them a factor 1000 and not 1024 apart.
https://www.bipm.org/documents/20126/41483022/SI-Brochure-9-EN.pdf
Page 143, table 7.
Also, these are suffixes not prefixes. :-)
+ const unsigned int base = use_iec ? 1024 : 1000;
+ uint64_t powi = 1;
+ uint16_t powj = 1;
+ uint8_t precision = 2;
+
+ if (count < base)
+ return snprintf(buf, buf_size, "%"PRIu64" ", count);
+
+ /* increase value by a factor of 1000/1024 and store
+ * if result is something a human can read
+ */
+ for (;;) {
+ powi *= base;
+ if (count / base < powi)
This would seem more logical to me as "count / powi < base" since it would
match the initial check for "count < base" (which is essentially the same
check since powi == 1).
+ break;
+
+ if (!prefix[1])
Since prefix is character string, the comparison should be against '\0',
according to DPDK coding style. The "!" should only be used on bool values.
So "if (prefix[1] == '\0')" or "if (*(prefix + 1) == '\0')".
+ break;
+ ++prefix;
+ }
+
+ /* try to guess a good number of digits for precision */
+ for (; precision > 0; precision--) {
+ powj *= 10;
+ if (count / powi < powj)
+ break;
+ }
+
+ return snprintf(buf, buf_size, "%.*f %c%s", precision,
+ (double)count / powi, *prefix, use_iec ? "i" : "");
+}
diff --git a/lib/eal/include/rte_common.h b/lib/eal/include/rte_common.h
index 386f11ae40..781c56adcd 100644
--- a/lib/eal/include/rte_common.h
+++ b/lib/eal/include/rte_common.h
@@ -14,9 +14,11 @@
#include <assert.h>
#include <limits.h>
+#include <stdbool.h>
#include <stdint.h>
#include <stdalign.h>
+#include <rte_compat.h>
#include <rte_config.h>
/* OS specific include */
@@ -919,6 +921,35 @@ __extension__ typedef uint64_t RTE_MARKER64[0];
uint64_t
rte_str_to_size(const char *str);
+/**
+ * Converts the uint64_t value provided to a human-readable string.
+ * It null-terminates the string, truncating the data if needed.
+ *
+ * Sample outputs with "use_iec" disabled and enabled:
+ * 0 : "0 ", "0 "
+ * 700 : "700 ", "700 "
+ * 1000 : "1.00 k", "1000 "
+ * 1024 : "1.02 k", "1.00 ki"
+ * 21474836480 : "21.5 G", "20.0 Gi"
+ * 109951162777600 : "110 T", "100 Ti"
+ *
I would omit the space before the suffixes in the output. As well as
looking better to me, it also solves the issue of the non-suffixed numbers
having a trailing space.
+ * @param buf
+ * Buffer to write the string to.
+ * @param buf_size
+ * Size of the buffer.
+ * @param count
+ * Number to convert.
+ * @param use_iec
+ * If true, use IEC units (1024-based), otherwise use SI units
(1000-based).
+ * @return
+ * Number of characters written (not including the null-terminator),
+ * or that would have been required when the buffer is too small.
+ */
+__rte_experimental
+int
+rte_size_to_str(char *buf, int buf_size,
+ uint64_t count, bool use_iec);
Again, no need to wrap.
+
/**
* Function to terminate the application immediately, printing an error
* message and returning the exit_code back to the shell.
diff --git a/lib/eal/version.map b/lib/eal/version.map
index a20c713eb1..01b6a7c190 100644
--- a/lib/eal/version.map
+++ b/lib/eal/version.map
@@ -398,6 +398,9 @@ EXPERIMENTAL {
# added in 24.11
rte_bitset_to_str;
rte_lcore_var_alloc;
+
+ # added in 25.07
+ rte_size_to_str;
};
INTERNAL {
--
2.48.1.vfs.0.1
