Re: [PATCH v4 10/10] kunit: string-stream: Test performance of string_stream

On Mon, 14 Aug 2023 at 21:23, Richard Fitzgerald rf@opensource.cirrus.com wrote:

Add a test of the speed and memory use of string_stream.

string_stream_performance_test() doesn't actually "test" anything (it cannot fail unless the system has run out of allocatable memory) but it measures the speed and memory consumption of the string_stream and reports the result.

This allows changes in the string_stream implementation to be compared.

Signed-off-by: Richard Fitzgerald rf@opensource.cirrus.com

Thanks, this is very useful.

My results are (UML): # string_stream_performance_test: Time elapsed: 5021 us # string_stream_performance_test: Total string length: 573890 # string_stream_performance_test: Bytes requested: 823930 # string_stream_performance_test: Actual bytes allocated: 1048312

KUnit isn't really ideal for performance testing, but this works well enough and fits in well alongside the other string stream tests.

Reviewed-by: David Gow davidgow@google.com

Cheers, -- David

lib/kunit/string-stream-test.c | 54 ++++++++++++++++++++++++++++++++++ 1 file changed, 54 insertions(+)

diff --git a/lib/kunit/string-stream-test.c b/lib/kunit/string-stream-test.c index 05bfade2bd8a..b55cc14f43fb 100644 --- a/lib/kunit/string-stream-test.c +++ b/lib/kunit/string-stream-test.c @@ -8,7 +8,9 @@

#include <kunit/static_stub.h> #include <kunit/test.h> +#include <linux/ktime.h> #include <linux/slab.h> +#include <linux/timekeeping.h>

#include "string-stream.h"

@@ -370,6 +372,57 @@ static void string_stream_auto_newline_test(struct kunit *test) "One\nTwo\nThree\nFour\nFive\nSix\nSeven\n\nEight\n"); }

+/*

• • This doesn't actually "test" anything. It reports time taken
• • and memory used for logging a large number of lines.
• */

+static void string_stream_performance_test(struct kunit *test) +{

•   struct string_stream_fragment *frag_container;
  

•   struct string_stream *stream;
  

•   char test_line[101];
  

•   ktime_t start_time, end_time;
  

•   size_t len, bytes_requested, actual_bytes_used, total_string_length;
  

•   int offset, i;
  

•   stream = alloc_string_stream(test, GFP_KERNEL);
  

•   KUNIT_ASSERT_NOT_ERR_OR_NULL(test, stream);
  

•   memset(test_line, 'x', sizeof(test_line) - 1);
  

•   test_line[sizeof(test_line) - 1] = '\0';
  

•   start_time = ktime_get();
  

•   for (i = 0; i < 10000; i++) {
  

•           offset = i % (sizeof(test_line) - 1);
  

•           string_stream_add(stream, "%s: %d\n", &test_line[offset], i);
  

•   }
  

•   end_time = ktime_get();
  

•   /*
  

•    * Calculate memory used. This doesn't include invisible
  

•    * overhead due to kernel allocator fragment size rounding.
  

•    */
  

•   bytes_requested = sizeof(*stream);
  

•   actual_bytes_used = ksize(stream);
  

•   total_string_length = 0;
  

•   list_for_each_entry(frag_container, &stream->fragments, node) {
  

•           bytes_requested += sizeof(*frag_container);
  

•           actual_bytes_used += ksize(frag_container);
  

•           len = strlen(frag_container->fragment);
  

•           total_string_length += len;
  

•           bytes_requested += len + 1; /* +1 for '\0' */
  

•           actual_bytes_used += ksize(frag_container->fragment);
  

•   }
  

•   kunit_info(test, "Time elapsed:           %lld us\n",
  

•              ktime_us_delta(end_time, start_time));
  

•   kunit_info(test, "Total string length:    %zu\n", total_string_length);
  

•   kunit_info(test, "Bytes requested:        %zu\n", bytes_requested);
  

•   kunit_info(test, "Actual bytes allocated: %zu\n", actual_bytes_used);
  

+}

static int string_stream_test_init(struct kunit *test) { struct string_stream_test_priv *priv; @@ -400,6 +453,7 @@ static struct kunit_case string_stream_test_cases[] = { KUNIT_CASE(string_stream_append_empty_string_test), KUNIT_CASE(string_stream_no_auto_newline_test), KUNIT_CASE(string_stream_auto_newline_test),

•   KUNIT_CASE(string_stream_performance_test),
    {}
  

};

-- 2.30.2