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| author | Matthew Wilcox <matthew.r.wilcox@intel.com> | 2011-02-06 07:28:06 -0500 |
|---|---|---|
| committer | Matthew Wilcox <matthew.r.wilcox@intel.com> | 2011-11-04 15:52:55 -0400 |
| commit | 58ffacb545f76fc2c65d1fbfa5acf5184a2a09e6 (patch) | |
| tree | 382cf8004b88f9d2bd2b86d78121938afa863e42 /drivers/block | |
| parent | b1ad37efcafe396ac3944853589688dd0ec3c64e (diff) | |
| download | linux-58ffacb545f76fc2c65d1fbfa5acf5184a2a09e6.tar.gz linux-58ffacb545f76fc2c65d1fbfa5acf5184a2a09e6.tar.bz2 linux-58ffacb545f76fc2c65d1fbfa5acf5184a2a09e6.zip | |
NVMe: Add a module parameter to use a threaded interrupt
We're currently calling bio_endio from hard interrupt context. This is
not a good idea for preemptible kernels as it will cause longer latencies.
Using a threaded interrupt will run the entire queue processing mechanism
(including bio_endio) in a thread, which can be preempted. Unfortuantely,
it also adds about 7us of latency to the single-I/O case, so make it a
module parameter for the moment.
Signed-off-by: Matthew Wilcox <matthew.r.wilcox@intel.com>
Diffstat (limited to 'drivers/block')
| -rw-r--r-- | drivers/block/nvme.c | 27 |
1 files changed, 27 insertions, 0 deletions
diff --git a/drivers/block/nvme.c b/drivers/block/nvme.c index 1c3cd6cc0ad9..60c3786bc787 100644 --- a/drivers/block/nvme.c +++ b/drivers/block/nvme.c @@ -44,6 +44,9 @@ static int nvme_major; module_param(nvme_major, int, 0); +static int use_threaded_interrupts; +module_param(use_threaded_interrupts, int, 0); + /* * Represents an NVM Express device. Each nvme_dev is a PCI function. */ @@ -455,6 +458,25 @@ static irqreturn_t nvme_irq(int irq, void *data) return nvme_process_cq(data); } +static irqreturn_t nvme_irq_thread(int irq, void *data) +{ + irqreturn_t result; + struct nvme_queue *nvmeq = data; + spin_lock(&nvmeq->q_lock); + result = nvme_process_cq(nvmeq); + spin_unlock(&nvmeq->q_lock); + return result; +} + +static irqreturn_t nvme_irq_check(int irq, void *data) +{ + struct nvme_queue *nvmeq = data; + struct nvme_completion cqe = nvmeq->cqes[nvmeq->cq_head]; + if ((le16_to_cpu(cqe.status) & 1) != nvmeq->cq_phase) + return IRQ_NONE; + return IRQ_WAKE_THREAD; +} + static void nvme_abort_command(struct nvme_queue *nvmeq, int cmdid) { spin_lock_irq(&nvmeq->q_lock); @@ -630,6 +652,11 @@ static struct nvme_queue *nvme_alloc_queue(struct nvme_dev *dev, int qid, static int queue_request_irq(struct nvme_dev *dev, struct nvme_queue *nvmeq, const char *name) { + if (use_threaded_interrupts) + return request_threaded_irq(dev->entry[nvmeq->cq_vector].vector, + nvme_irq_check, nvme_irq_thread, + IRQF_DISABLED | IRQF_SHARED, + name, nvmeq); return request_irq(dev->entry[nvmeq->cq_vector].vector, nvme_irq, IRQF_DISABLED | IRQF_SHARED, name, nvmeq); } |