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| author | Julian Wiedmann <jwi@linux.ibm.com> | 2020-06-16 14:13:00 +0200 |
|---|---|---|
| committer | Heiko Carstens <hca@linux.ibm.com> | 2020-07-20 10:55:26 +0200 |
| commit | a709423f7a3a452e5fa7442425817c1bdccd7926 (patch) | |
| tree | 88a7a830f87b34335fa01ad4de1becb48a3398cb /drivers/s390 | |
| parent | 2bbf282a5e8e7e6b36586718b484a36117b6b8a0 (diff) | |
| download | lwn-a709423f7a3a452e5fa7442425817c1bdccd7926.tar.gz lwn-a709423f7a3a452e5fa7442425817c1bdccd7926.zip | |
s390/qdio: remove internal polling in non-thinint path
For non-thinint devices in LPAR, qdio polls an idle Input Queue for a
little while to catch more work. But platform support for thinints has
been around practically _forever_ by now, so this micro-optimization is
seeing 0 actual use. Remove it to reduce the overall complexity of the
hot path.
In the meantime we also grew support for driver-level polling
(eg. NAPI in qeth), so it's quite questionable how useful this would
actually be on current kernels.
Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Diffstat (limited to 'drivers/s390')
| -rw-r--r-- | drivers/s390/cio/qdio.h | 3 | ||||
| -rw-r--r-- | drivers/s390/cio/qdio_main.c | 26 |
2 files changed, 2 insertions, 27 deletions
diff --git a/drivers/s390/cio/qdio.h b/drivers/s390/cio/qdio.h index 7f0aa95585a4..cd2df4ff8e0e 100644 --- a/drivers/s390/cio/qdio.h +++ b/drivers/s390/cio/qdio.h @@ -15,7 +15,6 @@ #define QDIO_BUSY_BIT_PATIENCE (100 << 12) /* 100 microseconds */ #define QDIO_BUSY_BIT_RETRY_DELAY 10 /* 10 milliseconds */ #define QDIO_BUSY_BIT_RETRIES 1000 /* = 10s retry time */ -#define QDIO_INPUT_THRESHOLD (500 << 12) /* 500 microseconds */ enum qdio_irq_states { QDIO_IRQ_STATE_INACTIVE, @@ -181,8 +180,6 @@ struct qdio_input_q { /* Batch of SBALs that we processed while polling the queue: */ unsigned int batch_start; unsigned int batch_count; - /* last time of noticing incoming data */ - u64 timestamp; }; struct qdio_output_q { diff --git a/drivers/s390/cio/qdio_main.c b/drivers/s390/cio/qdio_main.c index 0c1f186c6291..4fab8bba2cdd 100644 --- a/drivers/s390/cio/qdio_main.c +++ b/drivers/s390/cio/qdio_main.c @@ -510,14 +510,7 @@ static int get_inbound_buffer_frontier(struct qdio_q *q, unsigned int start) static int qdio_inbound_q_moved(struct qdio_q *q, unsigned int start) { - int count; - - count = get_inbound_buffer_frontier(q, start); - - if (count && !is_thinint_irq(q->irq_ptr) && MACHINE_IS_LPAR) - q->u.in.timestamp = get_tod_clock(); - - return count; + return get_inbound_buffer_frontier(q, start); } static inline int qdio_inbound_q_done(struct qdio_q *q, unsigned int start) @@ -535,22 +528,7 @@ static inline int qdio_inbound_q_done(struct qdio_q *q, unsigned int start) /* more work coming */ return 0; - if (is_thinint_irq(q->irq_ptr)) - return 1; - - /* don't poll under z/VM */ - if (MACHINE_IS_VM) - return 1; - - /* - * At this point we know, that inbound first_to_check - * has (probably) not moved (see qdio_inbound_processing). - */ - if (get_tod_clock_fast() > q->u.in.timestamp + QDIO_INPUT_THRESHOLD) { - DBF_DEV_EVENT(DBF_INFO, q->irq_ptr, "in done:%02x", start); - return 1; - } else - return 0; + return 1; } static inline void qdio_handle_aobs(struct qdio_q *q, int start, int count) |