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Commit e82a1567 authored by Peter Oberparleiter's avatar Peter Oberparleiter Committed by Martin Schwidefsky
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[S390] cio: reduce cpu utilization during device scan 



Minimize calls to cpu intensive function get_subchannel_by_schid()
by introducing function for_each_subchannel_staged() which
temporarily caches the information about registered subchannels
in a bitmap.

Signed-off-by: default avatarPeter Oberparleiter <peter.oberparleiter@de.ibm.com>
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent 4beee646

drivers/s390/cio/chsc.c

+32 −66
Original line number Diff line number Diff line
@@ -136,17 +136,13 @@ static void terminate_internal_io(struct subchannel *sch) 
		sch->driver->termination(sch);

}



static int

s390_subchannel_remove_chpid(struct device *dev, void *data)

static int s390_subchannel_remove_chpid(struct subchannel *sch, void *data)

{

	int j;

	int mask;

	struct subchannel *sch;

	struct chp_id *chpid;

	struct chp_id *chpid = data;

	struct schib schib;



	sch = to_subchannel(dev);

	chpid = data;

	for (j = 0; j < 8; j++) {

		mask = 0x80 >> j;

		if ((sch->schib.pmcw.pim & mask) &&
@@ -202,12 +198,10 @@ void chsc_chp_offline(struct chp_id chpid) 


	if (chp_get_status(chpid) <= 0)

		return;

	bus_for_each_dev(&css_bus_type, NULL, &chpid,

			 s390_subchannel_remove_chpid);

	for_each_subchannel_staged(s390_subchannel_remove_chpid, NULL, &chpid);

}



static int

s390_process_res_acc_new_sch(struct subchannel_id schid)

static int s390_process_res_acc_new_sch(struct subchannel_id schid, void *data)

{

	struct schib schib;

	/*
@@ -253,18 +247,10 @@ static int get_res_chpid_mask(struct chsc_ssd_info *ssd, 
	return 0;

}



static int

__s390_process_res_acc(struct subchannel_id schid, void *data)

static int __s390_process_res_acc(struct subchannel *sch, void *data)

{

	int chp_mask, old_lpm;

	struct res_acc_data *res_data;

	struct subchannel *sch;



	res_data = data;

	sch = get_subchannel_by_schid(schid);

	if (!sch)

		/* Check if a subchannel is newly available. */

		return s390_process_res_acc_new_sch(schid);

	struct res_acc_data *res_data = data;



	spin_lock_irq(sch->lock);

	chp_mask = get_res_chpid_mask(&sch->ssd_info, res_data);
@@ -283,7 +269,7 @@ __s390_process_res_acc(struct subchannel_id schid, void *data) 
		sch->driver->verify(sch);

out:

	spin_unlock_irq(sch->lock);

	put_device(&sch->dev);



	return 0;

}
@@ -306,7 +292,8 @@ static void s390_process_res_acc (struct res_acc_data *res_data) 
	 * The more information we have (info), the less scanning

	 * will we have to do.

	 */

	for_each_subchannel(__s390_process_res_acc, res_data);

	for_each_subchannel_staged(__s390_process_res_acc,

				   s390_process_res_acc_new_sch, res_data);

}



static int
@@ -500,8 +487,7 @@ void chsc_process_crw(void) 
	} while (sei_area->flags & 0x80);

}



static int

__chp_add_new_sch(struct subchannel_id schid)

static int __chp_add_new_sch(struct subchannel_id schid, void *data)

{

	struct schib schib;
@@ -515,35 +501,27 @@ __chp_add_new_sch(struct subchannel_id schid) 
}





static int

__chp_add(struct subchannel_id schid, void *data)

static int __chp_add(struct subchannel *sch, void *data)

{

	int i, mask;

	struct chp_id *chpid;

	struct subchannel *sch;



	chpid = data;

	sch = get_subchannel_by_schid(schid);

	if (!sch)

		/* Check if the subchannel is now available. */

		return __chp_add_new_sch(schid);

	struct chp_id *chpid = data;



	spin_lock_irq(sch->lock);

	for (i=0; i<8; i++) {

		mask = 0x80 >> i;

		if ((sch->schib.pmcw.pim & mask) &&

		    (sch->schib.pmcw.chpid[i] == chpid->id)) {

			if (stsch(sch->schid, &sch->schib) != 0) {

				/* Endgame. */

				spin_unlock_irq(sch->lock);

				return -ENXIO;

			}

		    (sch->schib.pmcw.chpid[i] == chpid->id))

			break;

	}

	}

	if (i==8) {

		spin_unlock_irq(sch->lock);

		return 0;

	}

	if (stsch(sch->schid, &sch->schib)) {

		spin_unlock_irq(sch->lock);

		css_schedule_eval(sch->schid);

		return 0;

	}

	sch->lpm = ((sch->schib.pmcw.pim &

		     sch->schib.pmcw.pam &

		     sch->schib.pmcw.pom)
@@ -553,7 +531,7 @@ __chp_add(struct subchannel_id schid, void *data) 
		sch->driver->verify(sch);



	spin_unlock_irq(sch->lock);

	put_device(&sch->dev);



	return 0;

}
@@ -565,7 +543,8 @@ void chsc_chp_online(struct chp_id chpid) 
	CIO_TRACE_EVENT(2, dbf_txt);



	if (chp_get_status(chpid) != 0)

		for_each_subchannel(__chp_add, &chpid);

		for_each_subchannel_staged(__chp_add, __chp_add_new_sch,

					   &chpid);

}



static void __s390_subchannel_vary_chpid(struct subchannel *sch,
@@ -616,25 +595,17 @@ static void __s390_subchannel_vary_chpid(struct subchannel *sch, 
	spin_unlock_irqrestore(sch->lock, flags);

}



static int s390_subchannel_vary_chpid_off(struct device *dev, void *data)

static int s390_subchannel_vary_chpid_off(struct subchannel *sch, void *data)

{

	struct subchannel *sch;

	struct chp_id *chpid;



	sch = to_subchannel(dev);

	chpid = data;

	struct chp_id *chpid = data;



	__s390_subchannel_vary_chpid(sch, *chpid, 0);

	return 0;

}



static int s390_subchannel_vary_chpid_on(struct device *dev, void *data)

static int s390_subchannel_vary_chpid_on(struct subchannel *sch, void *data)

{

	struct subchannel *sch;

	struct chp_id *chpid;



	sch = to_subchannel(dev);

	chpid = data;

	struct chp_id *chpid = data;



	__s390_subchannel_vary_chpid(sch, *chpid, 1);

	return 0;
@@ -644,13 +615,7 @@ static int 
__s390_vary_chpid_on(struct subchannel_id schid, void *data)

{

	struct schib schib;

	struct subchannel *sch;



	sch = get_subchannel_by_schid(schid);

	if (sch) {

		put_device(&sch->dev);

		return 0;

	}

	if (stsch_err(schid, &schib))

		/* We're through */

		return -ENXIO;
@@ -670,12 +635,13 @@ int chsc_chp_vary(struct chp_id chpid, int on) 
	 * Redo PathVerification on the devices the chpid connects to

	 */



	bus_for_each_dev(&css_bus_type, NULL, &chpid, on ?

			 s390_subchannel_vary_chpid_on :

			 s390_subchannel_vary_chpid_off);

	if (on)

		/* Scan for new devices on varied on path. */

		for_each_subchannel(__s390_vary_chpid_on, NULL);

		for_each_subchannel_staged(s390_subchannel_vary_chpid_on,

					   __s390_vary_chpid_on, &chpid);

	else

		for_each_subchannel_staged(s390_subchannel_vary_chpid_off,

					   NULL, &chpid);



	return 0;

}

drivers/s390/cio/css.c

+102 −18
Original line number Diff line number Diff line
@@ -51,6 +51,62 @@ for_each_subchannel(int(*fn)(struct subchannel_id, void *), void *data) 
	return ret;

}



struct cb_data {

	void *data;

	struct idset *set;

	int (*fn_known_sch)(struct subchannel *, void *);

	int (*fn_unknown_sch)(struct subchannel_id, void *);

};



static int call_fn_known_sch(struct device *dev, void *data)

{

	struct subchannel *sch = to_subchannel(dev);

	struct cb_data *cb = data;

	int rc = 0;



	idset_sch_del(cb->set, sch->schid);

	if (cb->fn_known_sch)

		rc = cb->fn_known_sch(sch, cb->data);

	return rc;

}



static int call_fn_unknown_sch(struct subchannel_id schid, void *data)

{

	struct cb_data *cb = data;

	int rc = 0;



	if (idset_sch_contains(cb->set, schid))

		rc = cb->fn_unknown_sch(schid, cb->data);

	return rc;

}



int for_each_subchannel_staged(int (*fn_known)(struct subchannel *, void *),

			       int (*fn_unknown)(struct subchannel_id,

			       void *), void *data)

{

	struct cb_data cb;

	int rc;



	cb.set = idset_sch_new();

	if (!cb.set)

		return -ENOMEM;

	idset_fill(cb.set);

	cb.data = data;

	cb.fn_known_sch = fn_known;

	cb.fn_unknown_sch = fn_unknown;

	/* Process registered subchannels. */

	rc = bus_for_each_dev(&css_bus_type, NULL, &cb, call_fn_known_sch);

	if (rc)

		goto out;

	/* Process unregistered subchannels. */

	if (fn_unknown)

		rc = for_each_subchannel(call_fn_unknown_sch, &cb);

out:

	idset_free(cb.set);



	return rc;

}



static struct subchannel *

css_alloc_subchannel(struct subchannel_id schid)

{
@@ -402,20 +458,56 @@ static int __init slow_subchannel_init(void) 
	return 0;

}



static void css_slow_path_func(struct work_struct *unused)

static int slow_eval_known_fn(struct subchannel *sch, void *data)

{

	struct subchannel_id schid;

	int eval;

	int rc;



	CIO_TRACE_EVENT(4, "slowpath");

	spin_lock_irq(&slow_subchannel_lock);

	init_subchannel_id(&schid);

	while (idset_sch_get_first(slow_subchannel_set, &schid)) {

		idset_sch_del(slow_subchannel_set, schid);

	eval = idset_sch_contains(slow_subchannel_set, sch->schid);

	idset_sch_del(slow_subchannel_set, sch->schid);

	spin_unlock_irq(&slow_subchannel_lock);

		css_evaluate_subchannel(schid, 1);

		spin_lock_irq(&slow_subchannel_lock);

	if (eval) {

		rc = css_evaluate_known_subchannel(sch, 1);

		if (rc == -EAGAIN)

			css_schedule_eval(sch->schid);

	}

	return 0;

}



static int slow_eval_unknown_fn(struct subchannel_id schid, void *data)

{

	int eval;

	int rc = 0;



	spin_lock_irq(&slow_subchannel_lock);

	eval = idset_sch_contains(slow_subchannel_set, schid);

	idset_sch_del(slow_subchannel_set, schid);

	spin_unlock_irq(&slow_subchannel_lock);

	if (eval) {

		rc = css_evaluate_new_subchannel(schid, 1);

		switch (rc) {

		case -EAGAIN:

			css_schedule_eval(schid);

			rc = 0;

			break;

		case -ENXIO:

		case -ENOMEM:

		case -EIO:

			/* These should abort looping */

			break;

		default:

			rc = 0;

		}

	}

	return rc;

}



static void css_slow_path_func(struct work_struct *unused)

{

	CIO_TRACE_EVENT(4, "slowpath");

	for_each_subchannel_staged(slow_eval_known_fn, slow_eval_unknown_fn,

				   NULL);

}



static DECLARE_WORK(slow_path_work, css_slow_path_func);
@@ -444,7 +536,6 @@ void css_schedule_eval_all(void) 
/* Reprobe subchannel if unregistered. */

static int reprobe_subchannel(struct subchannel_id schid, void *data)

{

	struct subchannel *sch;

	int ret;



	CIO_MSG_EVENT(6, "cio: reprobe 0.%x.%04x\n",
@@ -452,13 +543,6 @@ static int reprobe_subchannel(struct subchannel_id schid, void *data) 
	if (need_reprobe)

		return -EAGAIN;



	sch = get_subchannel_by_schid(schid);

	if (sch) {

		/* Already known. */

		put_device(&sch->dev);

		return 0;

	}



	ret = css_probe_device(schid);

	switch (ret) {

	case 0:
@@ -486,7 +570,7 @@ static void reprobe_all(struct work_struct *unused) 
	/* Make sure initial subchannel scan is done. */

	wait_event(ccw_device_init_wq,

		   atomic_read(&ccw_device_init_count) == 0);

	ret = for_each_subchannel(reprobe_subchannel, NULL);

	ret = for_each_subchannel_staged(NULL, reprobe_subchannel, NULL);



	CIO_MSG_EVENT(2, "reprobe done (rc=%d, need_reprobe=%d)\n", ret,

		      need_reprobe);

drivers/s390/cio/css.h

+3 −0
Original line number Diff line number Diff line
@@ -91,6 +91,9 @@ extern void css_driver_unregister(struct css_driver *); 
extern void css_sch_device_unregister(struct subchannel *);

extern struct subchannel * get_subchannel_by_schid(struct subchannel_id);

extern int css_init_done;

int for_each_subchannel_staged(int (*fn_known)(struct subchannel *, void *),

			       int (*fn_unknown)(struct subchannel_id,

			       void *), void *data);

extern int for_each_subchannel(int(*fn)(struct subchannel_id, void *), void *);

extern void css_process_crw(int, int);

extern void css_reiterate_subchannels(void);