Commit e1c0d82d authored Mar 27, 2015 by Haiyang Zhang Committed by Greg Kroah-Hartman Apr 03, 2015

hv_vmbus: Add gradually increased delay for retries in vmbus_post_msg()



Most of the retries can be done within a millisecond successfully, so we
sleep 1ms before the first retry, then gradually increase the retry
interval to 2^n with max value of 2048ms. Doing so, we will have shorter
overall delay time, because most of the cases succeed within 1-2 attempts.

Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
Reviewed-by: K. Y. Srinivasan <kys@microsoft.com>
Reviewed-by: Dexuan Cui <decui@microsoft.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent 0a1a86ac

drivers/hv/connection.c

+5 −2

Original line number	Diff line number	Diff line
		@@ -422,6 +422,7 @@ int vmbus_post_msg(void *buffer, size_t buflen)
		union hv_connection_id conn_id;
		int ret = 0;
		int retries = 0;
		u32 msec = 1;

		conn_id.asu32 = 0;
		conn_id.u.id = VMBUS_MESSAGE_CONNECTION_ID;
		@@ -431,7 +432,7 @@ int vmbus_post_msg(void *buffer, size_t buflen)
		* insufficient resources. Retry the operation a couple of
		* times before giving up.
		*/
		while (retries < 10) {
		while (retries < 20) {
		ret = hv_post_message(conn_id, 1, buffer, buflen);

		switch (ret) {
		@@ -454,7 +455,9 @@ int vmbus_post_msg(void *buffer, size_t buflen)
		}

		retries++;
		msleep(1000);
		msleep(msec);
		if (msec < 2048)
		msec *= 2;
		}
		return ret;
		}

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