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authorJulian Wiedmann <jwi@linux.ibm.com>2020-03-20 14:00:00 +0100
committerVasily Gorbik <gor@linux.ibm.com>2020-04-06 13:13:51 +0200
commit9c159bbc14ba196d590dc1a2fe7931ccfe73db98 (patch)
treeb50cb6f7a9fd9fe5274b545e8185324dedc34f9b /drivers/s390
parenta8a4ee2740bb6224271f06742884ec375c42cb9e (diff)
s390/qdio: clear DSCI early for polling drivers
Polling drivers in a configuration with 1 Input Queue currently keep their DSCI armed all the way through the poll cycle, until qdio_start_irq() clears it. _Any_ intermittent QDIO interrupt delivered to tiqdio_thinint_handler() will thus cause 1) the 'adapter_int' statistic to be incremented, 2) a call to tiqdio_call_inq_handlers() for this device, and then 3) the 'int_discarded' statistics to be incremented. This causes overhead & complexity in the IRQ path, along with ambiguity in the statistics. On the other hand the device should be in IRQ avoidance mode during a poll cycle, so there won't be a lot of DSCI ping-pong that this micro-optimization could prevent. So align the DSCI handling with what we already do for devices with multiple Input Queues: clear it right away while processing the IRQ. For the non-polling path this means that we no longer need to handle the 1-queue case separately. Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com> Reviewed-by: Benjamin Block <bblock@linux.ibm.com> Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Diffstat (limited to 'drivers/s390')
-rw-r--r--drivers/s390/cio/qdio.h1
-rw-r--r--drivers/s390/cio/qdio_main.c2
-rw-r--r--drivers/s390/cio/qdio_thinint.c25
3 files changed, 2 insertions, 26 deletions
diff --git a/drivers/s390/cio/qdio.h b/drivers/s390/cio/qdio.h
index b0beafc43d37..b8453b594679 100644
--- a/drivers/s390/cio/qdio.h
+++ b/drivers/s390/cio/qdio.h
@@ -374,7 +374,6 @@ int tiqdio_allocate_memory(void);
void tiqdio_free_memory(void);
int tiqdio_register_thinints(void);
void tiqdio_unregister_thinints(void);
-void clear_nonshared_ind(struct qdio_irq *);
int test_nonshared_ind(struct qdio_irq *);
/* prototypes for setup */
diff --git a/drivers/s390/cio/qdio_main.c b/drivers/s390/cio/qdio_main.c
index 9d6e51bcd072..bcc3ab14e72d 100644
--- a/drivers/s390/cio/qdio_main.c
+++ b/drivers/s390/cio/qdio_main.c
@@ -1643,8 +1643,6 @@ int qdio_start_irq(struct ccw_device *cdev)
if (!irq_ptr)
return -ENODEV;
- clear_nonshared_ind(irq_ptr);
-
for_each_input_queue(irq_ptr, q, i)
qdio_stop_polling(q);
diff --git a/drivers/s390/cio/qdio_thinint.c b/drivers/s390/cio/qdio_thinint.c
index c78c8dd18a89..ae50373617cd 100644
--- a/drivers/s390/cio/qdio_thinint.c
+++ b/drivers/s390/cio/qdio_thinint.c
@@ -82,32 +82,16 @@ void tiqdio_remove_device(struct qdio_irq *irq_ptr)
INIT_LIST_HEAD(&irq_ptr->entry);
}
-static inline int has_multiple_inq_on_dsci(struct qdio_irq *irq_ptr)
-{
- return irq_ptr->nr_input_qs > 1;
-}
-
static inline int references_shared_dsci(struct qdio_irq *irq_ptr)
{
return irq_ptr->dsci == &q_indicators[TIQDIO_SHARED_IND].ind;
}
-void clear_nonshared_ind(struct qdio_irq *irq_ptr)
-{
- if (!is_thinint_irq(irq_ptr))
- return;
- if (references_shared_dsci(irq_ptr) ||
- has_multiple_inq_on_dsci(irq_ptr))
- return;
- xchg(irq_ptr->dsci, 0);
-}
-
int test_nonshared_ind(struct qdio_irq *irq_ptr)
{
if (!is_thinint_irq(irq_ptr))
return 0;
- if (references_shared_dsci(irq_ptr) ||
- has_multiple_inq_on_dsci(irq_ptr))
+ if (references_shared_dsci(irq_ptr))
return 0;
if (*irq_ptr->dsci)
return 1;
@@ -127,8 +111,7 @@ static inline void tiqdio_call_inq_handlers(struct qdio_irq *irq)
struct qdio_q *q;
int i;
- if (!references_shared_dsci(irq) &&
- has_multiple_inq_on_dsci(irq))
+ if (!references_shared_dsci(irq))
xchg(irq->dsci, 0);
if (irq->irq_poll) {
@@ -140,10 +123,6 @@ static inline void tiqdio_call_inq_handlers(struct qdio_irq *irq)
return;
}
- if (!references_shared_dsci(irq) &&
- !has_multiple_inq_on_dsci(irq))
- xchg(irq->dsci, 0);
-
for_each_input_queue(irq, q, i) {
/*
* Call inbound processing but not directly