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Commit 50f769df authored by Jan Glauber's avatar Jan Glauber Committed by Martin Schwidefsky
Browse files

[S390] qdio: improve inbound buffer acknowledgement 



- Use automatic acknowledgement of incoming buffers in QEBSM mode
- Move ACK for non-QEBSM mode always to the newest buffer to prevent
  a race with qdio_stop_polling
- Remove the polling spinlock, the upper layer drivers return new buffers
  in the same code path and could not run in parallel
- Don't flood the error log in case of no-target-buffer-empty
- In handle_inbound we check if we would overwrite an ACK'ed buffer, if so
  advance the pointer to the oldest ACK'ed buffer so we don't overwrite an
  empty buffer in qdio_stop_polling

Signed-off-by: default avatarJan Glauber <jang@linux.vnet.ibm.com>
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent 22f99347

drivers/s390/cio/qdio.h

+12 −7
Original line number Diff line number Diff line
@@ -112,12 +112,12 @@ static inline int do_sqbs(u64 token, unsigned char state, int queue, 
}



static inline int do_eqbs(u64 token, unsigned char *state, int queue,

			  int *start, int *count)

			  int *start, int *count, int ack)

{

	register unsigned long _ccq asm ("0") = *count;

	register unsigned long _token asm ("1") = token;

	unsigned long _queuestart = ((unsigned long)queue << 32) | *start;

	unsigned long _state = 0;

	unsigned long _state = (unsigned long)ack << 63;



	asm volatile(

		"	.insn	rrf,0xB99c0000,%1,%2,0,0"
@@ -134,7 +134,7 @@ static inline int do_eqbs(u64 token, unsigned char *state, int queue, 
static inline int do_sqbs(u64 token, unsigned char state, int queue,

			  int *start, int *count) { return 0; }

static inline int do_eqbs(u64 token, unsigned char *state, int queue,

			  int *start, int *count) { return 0; }

			  int *start, int *count, int ack) { return 0; }

#endif /* CONFIG_64BIT */



struct qdio_irq;
@@ -187,11 +187,11 @@ struct qdio_input_q { 
	/* input buffer acknowledgement flag */

	int polling;



	/* how much sbals are acknowledged with qebsm */

	int ack_count;



	/* last time of noticing incoming data */

	u64 timestamp;



	/* lock for clearing the acknowledgement */

	spinlock_t lock;

};



struct qdio_output_q {
@@ -351,10 +351,13 @@ static inline unsigned long long get_usecs(void) 
	((bufnr + 1) & QDIO_MAX_BUFFERS_MASK)

#define add_buf(bufnr, inc) \

	((bufnr + inc) & QDIO_MAX_BUFFERS_MASK)

#define sub_buf(bufnr, dec) \

	((bufnr - dec) & QDIO_MAX_BUFFERS_MASK)



/* prototypes for thin interrupt */

void qdio_sync_after_thinint(struct qdio_q *q);

int get_buf_state(struct qdio_q *q, unsigned int bufnr, unsigned char *state);

int get_buf_state(struct qdio_q *q, unsigned int bufnr, unsigned char *state,

		  int auto_ack);

void qdio_check_outbound_after_thinint(struct qdio_q *q);

int qdio_inbound_q_moved(struct qdio_q *q);

void qdio_kick_inbound_handler(struct qdio_q *q);
@@ -388,6 +391,8 @@ int qdio_setup_irq(struct qdio_initialize *init_data); 
void qdio_print_subchannel_info(struct qdio_irq *irq_ptr,

				struct ccw_device *cdev);

void qdio_release_memory(struct qdio_irq *irq_ptr);

int qdio_setup_create_sysfs(struct ccw_device *cdev);

void qdio_setup_destroy_sysfs(struct ccw_device *cdev);

int qdio_setup_init(void);

void qdio_setup_exit(void);

drivers/s390/cio/qdio_debug.c

+5 −2
Original line number Diff line number Diff line
@@ -60,16 +60,18 @@ static int qstat_show(struct seq_file *m, void *v) 
	if (!q)

		return 0;



	seq_printf(m, "device state indicator: %d\n", *q->irq_ptr->dsci);

	seq_printf(m, "device state indicator: %d\n", *(u32 *)q->irq_ptr->dsci);

	seq_printf(m, "nr_used: %d\n", atomic_read(&q->nr_buf_used));

	seq_printf(m, "ftc: %d\n", q->first_to_check);

	seq_printf(m, "last_move_ftc: %d\n", q->last_move_ftc);

	seq_printf(m, "polling: %d\n", q->u.in.polling);

	seq_printf(m, "ack count: %d\n", q->u.in.ack_count);

	seq_printf(m, "slsb buffer states:\n");

	seq_printf(m, "|0      |8      |16     |24     |32     |40     |48     |56  63|\n");



	qdio_siga_sync_q(q);

	for (i = 0; i < QDIO_MAX_BUFFERS_PER_Q; i++) {

		get_buf_state(q, i, &state);

		get_buf_state(q, i, &state, 0);

		switch (state) {

		case SLSB_P_INPUT_NOT_INIT:

		case SLSB_P_OUTPUT_NOT_INIT:
@@ -101,6 +103,7 @@ static int qstat_show(struct seq_file *m, void *v) 
			seq_printf(m, "\n");

	}

	seq_printf(m, "\n");

	seq_printf(m, "|64     |72     |80     |88     |96     |104    |112    |   127|\n");

	return 0;

}

drivers/s390/cio/qdio_main.c

+118 −63
Original line number Diff line number Diff line
@@ -112,12 +112,13 @@ static inline int qdio_check_ccq(struct qdio_q *q, unsigned int ccq) 
 * @state: state of the extracted buffers

 * @start: buffer number to start at

 * @count: count of buffers to examine

 * @auto_ack: automatically acknowledge buffers

 *

 * Returns the number of successfull extracted equal buffer states.

 * Stops processing if a state is different from the last buffers state.

 */

static int qdio_do_eqbs(struct qdio_q *q, unsigned char *state,

			int start, int count)

			int start, int count, int auto_ack)

{

	unsigned int ccq = 0;

	int tmp_count = count, tmp_start = start;
@@ -130,7 +131,8 @@ static int qdio_do_eqbs(struct qdio_q *q, unsigned char *state, 
	if (!q->is_input_q)

		nr += q->irq_ptr->nr_input_qs;

again:

	ccq = do_eqbs(q->irq_ptr->sch_token, state, nr, &tmp_start, &tmp_count);

	ccq = do_eqbs(q->irq_ptr->sch_token, state, nr, &tmp_start, &tmp_count,

		      auto_ack);

	rc = qdio_check_ccq(q, ccq);



	/* At least one buffer was processed, return and extract the remaining
@@ -176,6 +178,9 @@ static int qdio_do_sqbs(struct qdio_q *q, unsigned char state, int start, 
	int nr = q->nr;

	int rc;



	if (!count)

		return 0;



	BUG_ON(!q->irq_ptr->sch_token);

	qdio_perf_stat_inc(&perf_stats.debug_sqbs_all);
@@ -203,7 +208,8 @@ static int qdio_do_sqbs(struct qdio_q *q, unsigned char state, int start, 


/* returns number of examined buffers and their common state in *state */

static inline int get_buf_states(struct qdio_q *q, unsigned int bufnr,

				 unsigned char *state, unsigned int count)

				 unsigned char *state, unsigned int count,

				 int auto_ack)

{

	unsigned char __state = 0;

	int i;
@@ -212,7 +218,7 @@ static inline int get_buf_states(struct qdio_q *q, unsigned int bufnr, 
	BUG_ON(count > QDIO_MAX_BUFFERS_PER_Q);



	if (is_qebsm(q))

		return qdio_do_eqbs(q, state, bufnr, count);

		return qdio_do_eqbs(q, state, bufnr, count, auto_ack);



	for (i = 0; i < count; i++) {

		if (!__state)
@@ -226,9 +232,9 @@ static inline int get_buf_states(struct qdio_q *q, unsigned int bufnr, 
}



inline int get_buf_state(struct qdio_q *q, unsigned int bufnr,

		  unsigned char *state)

		  unsigned char *state, int auto_ack)

{

	return get_buf_states(q, bufnr, state, 1);

	return get_buf_states(q, bufnr, state, 1, auto_ack);

}



/* wrap-around safe setting of slsb states, returns number of changed buffers */
@@ -376,29 +382,91 @@ void qdio_sync_after_thinint(struct qdio_q *q) 


inline void qdio_stop_polling(struct qdio_q *q)

{

	spin_lock_bh(&q->u.in.lock);

	if (!q->u.in.polling) {

		spin_unlock_bh(&q->u.in.lock);

	if (!q->u.in.polling)

		return;

	}



	q->u.in.polling = 0;

	qdio_perf_stat_inc(&perf_stats.debug_stop_polling);



	/* show the card that we are not polling anymore */

	if (is_qebsm(q)) {

		set_buf_states(q, q->last_move_ftc, SLSB_P_INPUT_NOT_INIT,

			       q->u.in.ack_count);

		q->u.in.ack_count = 0;

	} else

		set_buf_state(q, q->last_move_ftc, SLSB_P_INPUT_NOT_INIT);

	spin_unlock_bh(&q->u.in.lock);

}



static void announce_buffer_error(struct qdio_q *q)

static void announce_buffer_error(struct qdio_q *q, int count)

{

	q->qdio_error = QDIO_ERROR_SLSB_STATE;



	/* special handling for no target buffer empty */

	if ((!q->is_input_q &&

	    (q->sbal[q->first_to_check]->element[15].flags & 0xff) == 0x10)) {

		qdio_perf_stat_inc(&perf_stats.outbound_target_full);

		DBF_DEV_EVENT(DBF_INFO, q->irq_ptr, "OUTFULL FTC:%3d",

			      q->first_to_check);

		return;

	}



	DBF_ERROR("%4x BUF ERROR", SCH_NO(q));

	DBF_ERROR((q->is_input_q) ? "IN:%2d" : "OUT:%2d", q->nr);

	DBF_ERROR("FTC:%3d", q->first_to_check);

	DBF_ERROR("FTC:%3d C:%3d", q->first_to_check, count);

	DBF_ERROR("F14:%2x F15:%2x",

		  q->sbal[q->first_to_check]->element[14].flags & 0xff,

		  q->sbal[q->first_to_check]->element[15].flags & 0xff);

}



	q->qdio_error = QDIO_ERROR_SLSB_STATE;

static inline void inbound_primed(struct qdio_q *q, int count)

{

	int new;



	DBF_DEV_EVENT(DBF_INFO, q->irq_ptr, "in prim: %3d", count);



	/* for QEBSM the ACK was already set by EQBS */

	if (is_qebsm(q)) {

		if (!q->u.in.polling) {

			q->u.in.polling = 1;

			q->u.in.ack_count = count;

			q->last_move_ftc = q->first_to_check;

			return;

		}



		/* delete the previous ACK's */

		set_buf_states(q, q->last_move_ftc, SLSB_P_INPUT_NOT_INIT,

			       q->u.in.ack_count);

		q->u.in.ack_count = count;

		q->last_move_ftc = q->first_to_check;

		return;

	}



	/*

	 * ACK the newest buffer. The ACK will be removed in qdio_stop_polling

	 * or by the next inbound run.

	 */

	new = add_buf(q->first_to_check, count - 1);

	if (q->u.in.polling) {

		/* reset the previous ACK but first set the new one */

		set_buf_state(q, new, SLSB_P_INPUT_ACK);

		set_buf_state(q, q->last_move_ftc, SLSB_P_INPUT_NOT_INIT);

	}

	else {

		q->u.in.polling = 1;

		set_buf_state(q, q->first_to_check, SLSB_P_INPUT_ACK);

	}



	q->last_move_ftc = new;

	count--;

	if (!count)

		return;



	/*

	 * Need to change all PRIMED buffers to NOT_INIT, otherwise

	 * we're loosing initiative in the thinint code.

	 */

	set_buf_states(q, next_buf(q->first_to_check), SLSB_P_INPUT_NOT_INIT,

		       count);

}



static int get_inbound_buffer_frontier(struct qdio_q *q)
@@ -406,13 +474,6 @@ static int get_inbound_buffer_frontier(struct qdio_q *q) 
	int count, stop;

	unsigned char state;



	/*

	 * If we still poll don't update last_move_ftc, keep the

	 * previously ACK buffer there.

	 */

	if (!q->u.in.polling)

		q->last_move_ftc = q->first_to_check;



	/*

	 * Don't check 128 buffers, as otherwise qdio_inbound_q_moved

	 * would return 0.
@@ -433,34 +494,13 @@ static int get_inbound_buffer_frontier(struct qdio_q *q) 
	if (q->first_to_check == stop)

		goto out;



	count = get_buf_states(q, q->first_to_check, &state, count);

	count = get_buf_states(q, q->first_to_check, &state, count, 1);

	if (!count)

		goto out;



	switch (state) {

	case SLSB_P_INPUT_PRIMED:

		DBF_DEV_EVENT(DBF_INFO, q->irq_ptr, "in prim: %3d", count);



		/*

		 * Only ACK the first buffer. The ACK will be removed in

		 * qdio_stop_polling.

		 */

		if (q->u.in.polling)

			state = SLSB_P_INPUT_NOT_INIT;

		else {

			q->u.in.polling = 1;

			state = SLSB_P_INPUT_ACK;

		}

		set_buf_state(q, q->first_to_check, state);



		/*

		 * Need to change all PRIMED buffers to NOT_INIT, otherwise

		 * we're loosing initiative in the thinint code.

		 */

		if (count > 1)

			set_buf_states(q, next_buf(q->first_to_check),

				       SLSB_P_INPUT_NOT_INIT, count - 1);



		inbound_primed(q, count);

		/*

		 * No siga-sync needed for non-qebsm here, as the inbound queue

		 * will be synced on the next siga-r, resp.
@@ -470,7 +510,7 @@ static int get_inbound_buffer_frontier(struct qdio_q *q) 
		atomic_sub(count, &q->nr_buf_used);

		goto check_next;

	case SLSB_P_INPUT_ERROR:

		announce_buffer_error(q);

		announce_buffer_error(q, count);

		/* process the buffer, the upper layer will take care of it */

		q->first_to_check = add_buf(q->first_to_check, count);

		atomic_sub(count, &q->nr_buf_used);
@@ -516,7 +556,7 @@ static int qdio_inbound_q_done(struct qdio_q *q) 
	 */

	qdio_siga_sync_q(q);



	get_buf_state(q, q->first_to_check, &state);

	get_buf_state(q, q->first_to_check, &state, 0);

	if (state == SLSB_P_INPUT_PRIMED)

		/* we got something to do */

		return 0;
@@ -619,7 +659,7 @@ static int get_outbound_buffer_frontier(struct qdio_q *q) 
	if (q->first_to_check == stop)

		return q->first_to_check;



	count = get_buf_states(q, q->first_to_check, &state, count);

	count = get_buf_states(q, q->first_to_check, &state, count, 0);

	if (!count)

		return q->first_to_check;
@@ -638,7 +678,7 @@ static int get_outbound_buffer_frontier(struct qdio_q *q) 
			break;

		goto check_next;

	case SLSB_P_OUTPUT_ERROR:

		announce_buffer_error(q);

		announce_buffer_error(q, count);

		/* process the buffer, the upper layer will take care of it */

		q->first_to_check = add_buf(q->first_to_check, count);

		atomic_sub(count, &q->nr_buf_used);
@@ -1451,23 +1491,38 @@ static inline int buf_in_between(int bufnr, int start, int count) 
static void handle_inbound(struct qdio_q *q, unsigned int callflags,

			   int bufnr, int count)

{

	unsigned long flags;

	int used, rc;

	int used, rc, diff;



	/*

	 * do_QDIO could run in parallel with the queue tasklet so the

	 * upper-layer programm could empty the ACK'ed buffer here.

	 * If that happens we must clear the polling flag, otherwise

	 * qdio_stop_polling() could set the buffer to NOT_INIT after

	 * it was set to EMPTY which would kill us.

	 */

	spin_lock_irqsave(&q->u.in.lock, flags);

	if (q->u.in.polling)

		if (buf_in_between(q->last_move_ftc, bufnr, count))

	if (!q->u.in.polling)

		goto set;



	/* protect against stop polling setting an ACK for an emptied slsb */

	if (count == QDIO_MAX_BUFFERS_PER_Q) {

		/* overwriting everything, just delete polling status */

		q->u.in.polling = 0;

		q->u.in.ack_count = 0;

		goto set;

	} else if (buf_in_between(q->last_move_ftc, bufnr, count)) {

		if (is_qebsm(q)) {

			/* partial overwrite, just update last_move_ftc */

			diff = add_buf(bufnr, count);

			diff = sub_buf(diff, q->last_move_ftc);

			q->u.in.ack_count -= diff;

			if (q->u.in.ack_count <= 0) {

				q->u.in.polling = 0;

				q->u.in.ack_count = 0;

				/* TODO: must we set last_move_ftc to something meaningful? */

				goto set;

			}

			q->last_move_ftc = add_buf(q->last_move_ftc, diff);

		}

		else

			/* the only ACK will be deleted, so stop polling */

			q->u.in.polling = 0;

	}



set:

	count = set_buf_states(q, bufnr, SLSB_CU_INPUT_EMPTY, count);

	spin_unlock_irqrestore(&q->u.in.lock, flags);



	used = atomic_add_return(count, &q->nr_buf_used) - count;

	BUG_ON(used + count > QDIO_MAX_BUFFERS_PER_Q);
@@ -1535,7 +1590,7 @@ static void handle_outbound(struct qdio_q *q, unsigned int callflags, 
	}



	/* try to fast requeue buffers */

	get_buf_state(q, prev_buf(bufnr), &state);

	get_buf_state(q, prev_buf(bufnr), &state, 0);

	if (state != SLSB_CU_OUTPUT_PRIMED)

		qdio_kick_outbound_q(q);

	else {

drivers/s390/cio/qdio_perf.c

+2 −0
Original line number Diff line number Diff line
@@ -74,6 +74,8 @@ static int qdio_perf_proc_show(struct seq_file *m, void *v) 
	seq_printf(m, "\n");

	seq_printf(m, "Number of fast requeues (outg. SBAL w/o SIGA)\t: %li\n",

		   (long)atomic_long_read(&perf_stats.fast_requeue));

	seq_printf(m, "Number of outbound target full condition\t: %li\n",

		   (long)atomic_long_read(&perf_stats.outbound_target_full));

	seq_printf(m, "Number of outbound tasklet mod_timer calls\t: %li\n",

		   (long)atomic_long_read(&perf_stats.debug_tl_out_timer));

	seq_printf(m, "Number of stop polling calls\t\t\t: %li\n",

drivers/s390/cio/qdio_perf.h

+1 −0
Original line number Diff line number Diff line
@@ -36,6 +36,7 @@ struct qdio_perf_stats { 
	atomic_long_t inbound_handler;

	atomic_long_t outbound_handler;

	atomic_long_t fast_requeue;

	atomic_long_t outbound_target_full;



	/* for debugging */

	atomic_long_t debug_tl_out_timer;