greybus: loopback: remove redundant timestamping

It is of more interest to graphing system performance to base our
timestamps on the time it takes a greybus_operation_sync() to complete.
Higher level timestamping code is less accurate and not relevant to
throughput and latency characterization.

Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>

diff --git a/drivers/staging/greybus/loopback.c b/drivers/staging/greybus/loopback.c
index 229494833a16bbb00e236f751b0b38b0c06337b2..5f7c1a6256ccaaa1c8c19b32150d8063d4a14380 100644 (file)
--- a/drivers/staging/greybus/loopback.c
+++ b/drivers/staging/greybus/loopback.c
@@ -43,8 +43,6 @@ struct gb_loopback {
        struct gb_loopback_stats latency;
        struct gb_loopback_stats throughput;
        struct gb_loopback_stats requests_per_second;
-       struct timeval ts;
-       struct timeval te;
        u64 elapsed_nsecs;
        u32 error;
 };
@@ -180,11 +178,9 @@ static struct attribute *loopback_attrs[] = {
 };
 ATTRIBUTE_GROUPS(loopback);
 
-static int gb_loopback_sink(struct gb_loopback *gb,
-                               struct timeval *tping, u32 len)
+static int gb_loopback_sink(struct gb_loopback *gb, u32 len)
 {
        struct timeval ts, te;
-       u64 elapsed_nsecs;
        struct gb_loopback_transfer_request *request;
        int retval;
 
@@ -199,18 +195,15 @@ static int gb_loopback_sink(struct gb_loopback *gb,
                                   request, len + sizeof(*request), NULL, 0);
 
        do_gettimeofday(&te);
-       elapsed_nsecs = timeval_to_ns(&te) - timeval_to_ns(&ts);
-       *tping = ns_to_timeval(elapsed_nsecs);
+       gb->elapsed_nsecs = timeval_to_ns(&te) - timeval_to_ns(&ts);
 
        kfree(request);
        return retval;
 }
 
-static int gb_loopback_transfer(struct gb_loopback *gb,
-                               struct timeval *tping, u32 len)
+static int gb_loopback_transfer(struct gb_loopback *gb, u32 len)
 {
        struct timeval ts, te;
-       u64 elapsed_nsecs;
        struct gb_loopback_transfer_request *request;
        struct gb_loopback_transfer_response *response;
        int retval;
@@ -231,8 +224,7 @@ static int gb_loopback_transfer(struct gb_loopback *gb,
                                   request, len + sizeof(*request),
                                   response, len + sizeof(*response));
        do_gettimeofday(&te);
-       elapsed_nsecs = timeval_to_ns(&te) - timeval_to_ns(&ts);
-       *tping = ns_to_timeval(elapsed_nsecs);
+       gb->elapsed_nsecs = timeval_to_ns(&te) - timeval_to_ns(&ts);
 
        if (retval)
                goto gb_error;
@@ -247,18 +239,16 @@ gb_error:
        return retval;
 }
 
-static int gb_loopback_ping(struct gb_loopback *gb, struct timeval *tping)
+static int gb_loopback_ping(struct gb_loopback *gb)
 {
        struct timeval ts, te;
-       u64 elapsed_nsecs;
        int retval;
 
        do_gettimeofday(&ts);
        retval = gb_operation_sync(gb->connection, GB_LOOPBACK_TYPE_PING,
                                   NULL, 0, NULL, 0);
        do_gettimeofday(&te);
-       elapsed_nsecs = timeval_to_ns(&te) - timeval_to_ns(&ts);
-       *tping = ns_to_timeval(elapsed_nsecs);
+       gb->elapsed_nsecs = timeval_to_ns(&te) - timeval_to_ns(&ts);
 
        return retval;
 }
@@ -324,7 +314,6 @@ static void gb_loopback_reset_stats(struct gb_loopback *gb)
        memcpy(&gb->throughput, &reset, sizeof(struct gb_loopback_stats));
        memcpy(&gb->requests_per_second, &reset,
               sizeof(struct gb_loopback_stats));
-       memset(&gb->ts, 0, sizeof(struct timeval));
 }
 
 static void gb_loopback_update_stats(struct gb_loopback_stats *stats, u64 val)
@@ -375,8 +364,7 @@ static void gb_loopback_throughput_update(struct gb_loopback *gb, u32 latency)
        gb_loopback_update_stats(&gb->throughput, throughput);
 }
 
-static void gb_loopback_calculate_stats(struct gb_loopback *gb,
-                                       struct timeval *tlat)
+static void gb_loopback_calculate_stats(struct gb_loopback *gb)
 {
        u32 lat;
        u64 tmp;
@@ -397,7 +385,6 @@ static void gb_loopback_calculate_stats(struct gb_loopback *gb,
 static int gb_loopback_fn(void *data)
 {
        int error = 0;
-       struct timeval tlat = {0, 0};
        struct gb_loopback *gb = (struct gb_loopback *)data;
 
        while (1) {
@@ -416,21 +403,15 @@ static int gb_loopback_fn(void *data)
                                continue;
                        }
                }
-               if (gb->ts.tv_usec == 0 && gb->ts.tv_sec == 0)
-                       do_gettimeofday(&gb->ts);
                if (gb->type == GB_LOOPBACK_TYPE_PING)
-                       error = gb_loopback_ping(gb, &tlat);
+                       error = gb_loopback_ping(gb);
                else if (gb->type == GB_LOOPBACK_TYPE_TRANSFER)
-                       error = gb_loopback_transfer(gb, &tlat, gb->size);
+                       error = gb_loopback_transfer(gb, gb->size);
                else if (gb->type == GB_LOOPBACK_TYPE_SINK)
-                       error = gb_loopback_sink(gb, &tlat, gb->size);
+                       error = gb_loopback_sink(gb, gb->size);
                if (error)
                        gb->error++;
-               do_gettimeofday(&gb->te);
-               gb->elapsed_nsecs = timeval_to_ns(&gb->te) -
-                                       timeval_to_ns(&gb->ts);
-               gb_loopback_calculate_stats(gb, &tlat);
-               gb->ts = gb->te;
+               gb_loopback_calculate_stats(gb);
                if (gb->ms_wait)
                        msleep(gb->ms_wait);
        }