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From: Chaitanya Kulkarni <Chaitanya.Kulkarni@wdc.com>
To: Max Gurtovoy <maxg@mellanox.com>,
	"sagi@grimberg.me" <sagi@grimberg.me>, "hch@lst.de" <hch@lst.de>
Cc: "linux-nvme@lists.infradead.org" <linux-nvme@lists.infradead.org>
Subject: Re: [RFC PATCH 1/2] nvmet: add bdev-ns polling support
Date: Tue, 21 Jan 2020 19:22:01 +0000	[thread overview]
Message-ID: <DM6PR04MB575431D7764F7D4BB98AFA5B860D0@DM6PR04MB5754.namprd04.prod.outlook.com> (raw)
In-Reply-To: <2c5f45ab-7ac1-b904-bc7b-1f272484b845@mellanox.com>

Please see my in-line comments.
On 01/20/2020 04:52 AM, Max Gurtovoy wrote:
>
> On 12/10/2019 8:25 AM, Chaitanya Kulkarni wrote:
>> This patch adds support for the bdev-ns polling. We also add a new
>> file to keep polling code separate (io-poll.c). The newly added
>> configfs attribute allows user to enable/disable polling.
>>
>> We only enable polling for the READ/WRITE operation based on support
>> from bdev and and use_poll configfs attr.
>>
>> We configure polling per namespace. For each namespace we create
>> polling threads. For general approach please have a look at the
>> cover-letter of this patch-series.
>
> It would be great to get some numbers here to learn about the trade-off
> for this approach.
>
>

Already posted these numbers with QEMU nvme-loop here :-
http://lists.infradead.org/pipermail/linux-nvme/2020-January/028692.html

IOPS/BW:-

Default:-
read: IOPS=52.8k, BW=206MiB/s (216MB/s)(6188MiB/30001msec)
read: IOPS=54.3k, BW=212MiB/s (223MB/s)(6369MiB/30001msec)
read: IOPS=53.5k, BW=209MiB/s (219MB/s)(6274MiB/30001msec)
Poll:-
read: IOPS=68.4k, BW=267MiB/s (280MB/s)(8011MiB/30001msec)
read: IOPS=69.3k, BW=271MiB/s (284MB/s)(8124MiB/30001msec)
read: IOPS=69.4k, BW=271MiB/s (284MB/s)(8132MiB/30001msec)

mpstat:-
Default:-
CPU %usr %nice |%sys| %iowait %irq %soft %steal %guest %gnice %idle
---------------------------------------------------------
all 1.18 0.00 |60.14| 0.00 0.00 0.00 0.08 0.00 0.00 38.60
---------------------------------------------------------
0 0.00 0.00 | 32.00 |0.00 0.00 0.00 0.00 0.00 0.00 68.00
1 1.01 0.00 | 42.42 |0.00 0.00 0.00 0.00 0.00 0.00 56.57
2 1.01 0.00 | 57.58 |0.00 0.00 0.00 0.00 0.00 0.00 41.41
3 2.02 0.00 | 79.80 |0.00 0.00 0.00 0.00 0.00 0.00 18.18
4 1.01 0.00 | 63.64 |0.00 0.00 0.00 0.00 0.00 0.00 35.35
5 3.09 0.00 | 63.92 |0.00 0.00 0.00 0.00 0.00 0.00 32.99
6 2.02 0.00 | 75.76 |0.00 0.00 0.00 0.00 0.00 0.00 22.22
7 1.02 0.00 | 57.14 |0.00 0.00 0.00 0.00 0.00 0.00 41.84
8 0.00 0.00 | 67.01 |0.00 0.00 0.00 0.00 0.00 0.00 32.99
9 1.01 0.00 | 59.60 |0.00 0.00 0.00 0.00 0.00 0.00 39.39
10 1.02 0.00| 62.24 |0.00 0.00 0.00 0.00 0.00 0.00 36.73
11 1.02 0.00| 62.24 |0.00 0.00 0.00 0.00 0.00 0.00 36.73

Poll:-
CPU %usr %nice |%sys| %iowait %irq %soft %steal %guest %gnice %idle
---------------------------------------------------------
all 1.08 0.00 98.08 0.00 0.00 0.00 0.08 0.00 0.00 0.75
---------------------------------------------------------
0 2.00 0.00 | 97.00 |0.00 0.00 0.00 0.00 0.00 0.00 1.00
1 0.00 0.00 | 97.00 |0.00 0.00 0.00 0.00 0.00 0.00 3.00
2 1.00 0.00 | 99.00 |0.00 0.00 0.00 0.00 0.00 0.00 0.00
3 1.00 0.00 | 99.00 |0.00 0.00 0.00 0.00 0.00 0.00 0.00
4 1.01 0.00 | 98.99 |0.00 0.00 0.00 0.00 0.00 0.00 0.00
5 1.00 0.00 | 99.00 |0.00 0.00 0.00 0.00 0.00 0.00 0.00
6 0.99 0.00 | 99.01 |0.00 0.00 0.00 0.00 0.00 0.00 0.00
7 1.00 0.00 | 97.00 |0.00 0.00 0.00 0.00 0.00 0.00 2.00
8 1.00 0.00 | 99.00 |0.00 0.00 0.00 0.00 0.00 0.00 0.00
9 1.00 0.00 | 99.00 |0.00 0.00 0.00 0.00 0.00 0.00 0.00
10 1.98 0.00| 94.06 |0.00 0.00 0.00 0.00 0.00 0.00 3.96
11 1.00 0.00| 99.00 |0.00 0.00 0.00 0.00 0.00 0.00 0.00

>>
>> Signed-off-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
>> ---
>>    drivers/nvme/target/Makefile      |   3 +-
>>    drivers/nvme/target/configfs.c    |  29 ++++++
>>    drivers/nvme/target/core.c        |  13 +++
>>    drivers/nvme/target/io-cmd-bdev.c |  61 +++++++++--
>>    drivers/nvme/target/io-poll.c     | 165 ++++++++++++++++++++++++++++++
>>    drivers/nvme/target/nvmet.h       |  31 +++++-
>>    6 files changed, 291 insertions(+), 11 deletions(-)
>>    create mode 100644 drivers/nvme/target/io-poll.c
>>
>> diff --git a/drivers/nvme/target/Makefile b/drivers/nvme/target/Makefile
>> index 2b33836f3d3e..8877ba16305c 100644
>> --- a/drivers/nvme/target/Makefile
>> +++ b/drivers/nvme/target/Makefile
>> @@ -10,7 +10,8 @@ obj-$(CONFIG_NVME_TARGET_FCLOOP)	+= nvme-fcloop.o
>>    obj-$(CONFIG_NVME_TARGET_TCP)		+= nvmet-tcp.o
>>
>>    nvmet-y		+= core.o configfs.o admin-cmd.o fabrics-cmd.o \
>> -			discovery.o io-cmd-file.o io-cmd-bdev.o
>> +			discovery.o io-cmd-file.o io-cmd-bdev.o \
>> +			io-poll.o
>>    nvme-loop-y	+= loop.o
>>    nvmet-rdma-y	+= rdma.o
>>    nvmet-fc-y	+= fc.o
>> diff --git a/drivers/nvme/target/configfs.c b/drivers/nvme/target/configfs.c
>> index 98613a45bd3b..0e6e8b0dbf79 100644
>> --- a/drivers/nvme/target/configfs.c
>> +++ b/drivers/nvme/target/configfs.c
>> @@ -545,6 +545,34 @@ static ssize_t nvmet_ns_buffered_io_store(struct config_item *item,
>>
>>    CONFIGFS_ATTR(nvmet_ns_, buffered_io);
>>
>> +static ssize_t nvmet_ns_use_poll_show(struct config_item *item, char *page)
>> +{
>> +	return sprintf(page, "%d\n", to_nvmet_ns(item)->use_poll);
>> +}
>> +
>> +static ssize_t nvmet_ns_use_poll_store(struct config_item *item,
>> +		const char *page, size_t count)
>> +{
>> +	struct nvmet_ns *ns = to_nvmet_ns(item);
>> +	bool val;
>> +
>> +	if (strtobool(page, &val))
>> +		return -EINVAL;
>> +
>> +	mutex_lock(&ns->subsys->lock);
>> +	if (ns->enabled) {
>> +		pr_err("disable ns before setting use_poll value.\n");
>> +		mutex_unlock(&ns->subsys->lock);
>> +		return -EINVAL;
>> +	}
>> +
>> +	ns->use_poll = val;
>> +	mutex_unlock(&ns->subsys->lock);
>> +	return count;
>> +}
>> +
>> +CONFIGFS_ATTR(nvmet_ns_, use_poll);
>> +
>>    static struct configfs_attribute *nvmet_ns_attrs[] = {
>>    	&nvmet_ns_attr_device_path,
>>    	&nvmet_ns_attr_device_nguid,
>> @@ -552,6 +580,7 @@ static struct configfs_attribute *nvmet_ns_attrs[] = {
>>    	&nvmet_ns_attr_ana_grpid,
>>    	&nvmet_ns_attr_enable,
>>    	&nvmet_ns_attr_buffered_io,
>> +	&nvmet_ns_attr_use_poll,
>>    #ifdef CONFIG_PCI_P2PDMA
>>    	&nvmet_ns_attr_p2pmem,
>>    #endif
>> diff --git a/drivers/nvme/target/core.c b/drivers/nvme/target/core.c
>> index 28438b833c1b..d8f9130d1cd1 100644
>> --- a/drivers/nvme/target/core.c
>> +++ b/drivers/nvme/target/core.c
>> @@ -510,6 +510,18 @@ static void nvmet_p2pmem_ns_add_p2p(struct nvmet_ctrl *ctrl,
>>    		ns->nsid);
>>    }
>>
>> +inline void nvmet_req_done(struct nvmet_req *req)
>> +{
>> +	if (req->ns->bdev)
>> +		nvmet_bdev_req_complete(req);
>> +}
>> +
>> +inline void nvmet_req_poll_complete(struct nvmet_req *req)
>> +{
>> +	if (req->ns->bdev)
>> +		nvmet_bdev_poll_complete(req);
>> +}
>> +
>>    int nvmet_ns_enable(struct nvmet_ns *ns)
>>    {
>>    	struct nvmet_subsys *subsys = ns->subsys;
>> @@ -653,6 +665,7 @@ struct nvmet_ns *nvmet_ns_alloc(struct nvmet_subsys *subsys, u32 nsid)
>>
>>    	uuid_gen(&ns->uuid);
>>    	ns->buffered_io = false;
>> +	ns->use_poll = false;
>>
>>    	return ns;
>>    }
>> diff --git a/drivers/nvme/target/io-cmd-bdev.c b/drivers/nvme/target/io-cmd-bdev.c
>> index b6fca0e421ef..13507e0cbc1d 100644
>> --- a/drivers/nvme/target/io-cmd-bdev.c
>> +++ b/drivers/nvme/target/io-cmd-bdev.c
>> @@ -49,10 +49,11 @@ void nvmet_bdev_set_limits(struct block_device *bdev, struct nvme_id_ns *id)
>>
>>    int nvmet_bdev_ns_enable(struct nvmet_ns *ns)
>>    {
>> +	int fmode = FMODE_READ | FMODE_WRITE;
>> +	struct request_queue *q;
>>    	int ret;
>>
>> -	ns->bdev = blkdev_get_by_path(ns->device_path,
>> -			FMODE_READ | FMODE_WRITE, NULL);
>> +	ns->bdev = blkdev_get_by_path(ns->device_path, fmode, NULL);
>>    	if (IS_ERR(ns->bdev)) {
>>    		ret = PTR_ERR(ns->bdev);
>>    		if (ret != -ENOTBLK) {
>> @@ -60,16 +61,21 @@ int nvmet_bdev_ns_enable(struct nvmet_ns *ns)
>>    					ns->device_path, PTR_ERR(ns->bdev));
>>    		}
>>    		ns->bdev = NULL;
>> -		return ret;
>> +		goto out;
>>    	}
>>    	ns->size = i_size_read(ns->bdev->bd_inode);
>>    	ns->blksize_shift = blksize_bits(bdev_logical_block_size(ns->bdev));
>> -	return 0;
>> +	q = bdev_get_queue(ns->bdev);
>> +	ns->poll = ns->use_poll && test_bit(QUEUE_FLAG_POLL, &q->queue_flags);
>> +	ret = ns->poll ? nvmet_ns_start_poll(ns) : 0;
>> +out:
>> +	return ret;
>>    }
>>
>>    void nvmet_bdev_ns_disable(struct nvmet_ns *ns)
>>    {
>>    	if (ns->bdev) {
>> +		ns->poll ? nvmet_ns_stop_poll(ns) : 0;
>
> can you please use an "if" statement instead of the above convention ?
>

This is just as RFC, will send out formal patch series with all the
coding style fixes.

>
>>    		blkdev_put(ns->bdev, FMODE_WRITE | FMODE_READ);
>>    		ns->bdev = NULL;
>>    	}
>> @@ -133,15 +139,39 @@ static u16 blk_to_nvme_status(struct nvmet_req *req, blk_status_t blk_sts)
>>    	return status;
>>    }
>>
>> -static void nvmet_bio_done(struct bio *bio)
>> +void nvmet_bdev_req_complete(struct nvmet_req *req)
>>    {
>> -	struct nvmet_req *req = bio->bi_private;
>> +	struct bio *bio = req->b.last_bio;
>>
>>    	nvmet_req_complete(req, blk_to_nvme_status(req, bio->bi_status));
>>    	if (bio != &req->b.inline_bio)
>>    		bio_put(bio);
>>    }
>>
>> +static void nvmet_bio_done(struct bio *bio)
>> +{
>> +	struct nvmet_req *req = bio->bi_private;
>> +
>> +	req->b.last_bio = bio;
>> +
>> +	req->poll ? complete(&req->wait) : nvmet_bdev_req_complete(req);
>
> Same here for the "if". Lets keep the code as readable as we can
>
Same as above.
>
>> +}
>> +
>> +void nvmet_bdev_poll_complete(struct nvmet_req *req)
>> +{
>> +	struct request_queue *q = bdev_get_queue(req->ns->bdev);
>> +
>> +	while (!completion_done(&req->wait)) {
>> +		int ret = blk_poll(q, req->b.cookie, true);
>> +
>> +		if (ret < 0) {
>> +			pr_err("tid %d poll error %d", req->t->id, ret);
>> +			break;
>> +		}
>> +	}
>> +	nvmet_bdev_req_complete(req);
>> +}
>> +IOPS/BW:-

Default:-
read: IOPS=52.8k, BW=206MiB/s (216MB/s)(6188MiB/30001msec)
read: IOPS=54.3k, BW=212MiB/s (223MB/s)(6369MiB/30001msec)
read: IOPS=53.5k, BW=209MiB/s (219MB/s)(6274MiB/30001msec)
Poll:-
read: IOPS=68.4k, BW=267MiB/s (280MB/s)(8011MiB/30001msec)
read: IOPS=69.3k, BW=271MiB/s (284MB/s)(8124MiB/30001msec)
read: IOPS=69.4k, BW=271MiB/s (284MB/s)(8132MiB/30001msec)

mpstat:-
Default:-
CPU %usr %nice |%sys| %iowait %irq %soft %steal %guest %gnice %idle
---------------------------------------------------------
all 1.18 0.00 |60.14| 0.00 0.00 0.00 0.08 0.00 0.00 38.60
---------------------------------------------------------
0 0.00 0.00 | 32.00 |0.00 0.00 0.00 0.00 0.00 0.00 68.00
1 1.01 0.00 | 42.42 |0.00 0.00 0.00 0.00 0.00 0.00 56.57
2 1.01 0.00 | 57.58 |0.00 0.00 0.00 0.00 0.00 0.00 41.41
3 2.02 0.00 | 79.80 |0.00 0.00 0.00 0.00 0.00 0.00 18.18
4 1.01 0.00 | 63.64 |0.00 0.00 0.00 0.00 0.00 0.00 35.35
5 3.09 0.00 | 63.92 |0.00 0.00 0.00 0.00 0.00 0.00 32.99
6 2.02 0.00 | 75.76 |0.00 0.00 0.00 0.00 0.00 0.00 22.22
7 1.02 0.00 | 57.14 |0.00 0.00 0.00 0.00 0.00 0.00 41.84
8 0.00 0.00 | 67.01 |0.00 0.00 0.00 0.00 0.00 0.00 32.99
9 1.01 0.00 | 59.60 |0.00 0.00 0.00 0.00 0.00 0.00 39.39
10 1.02 0.00| 62.24 |0.00 0.00 0.00 0.00 0.00 0.00 36.73
11 1.02 0.00| 62.24 |0.00 0.00 0.00 0.00 0.00 0.00 36.73

Poll:-
CPU %usr %nice |%sys| %iowait %irq %soft %steal %guest %gnice %idle
---------------------------------------------------------
all 1.08 0.00 98.08 0.00 0.00 0.00 0.08 0.00 0.00 0.75
---------------------------------------------------------
0 2.00 0.00 | 97.00 |0.00 0.00 0.00 0.00 0.00 0.00 1.00
1 0.00 0.00 | 97.00 |0.00 0.00 0.00 0.00 0.00 0.00 3.00
2 1.00 0.00 | 99.00 |0.00 0.00 0.00 0.00 0.00 0.00 0.00
3 1.00 0.00 | 99.00 |0.00 0.00 0.00 0.00 0.00 0.00 0.00
4 1.01 0.00 | 98.99 |0.00 0.00 0.00 0.00 0.00 0.00 0.00
5 1.00 0.00 | 99.00 |0.00 0.00 0.00 0.00 0.00 0.00 0.00
6 0.99 0.00 | 99.01 |0.00 0.00 0.00 0.00 0.00 0.00 0.00
7 1.00 0.00 | 97.00 |0.00 0.00 0.00 0.00 0.00 0.00 2.00
8 1.00 0.00 | 99.00 |0.00 0.00 0.00 0.00 0.00 0.00 0.00
9 1.00 0.00 | 99.00 |0.00 0.00 0.00 0.00 0.00 0.00 0.00
10 1.98 0.00| 94.06 |0.00 0.00 0.00 0.00 0.00 0.00 3.96
11 1.00 0.00| 99.00 |0.00 0.00 0.00 0.00 0.00 0.00 0.00

>>    static void nvmet_bdev_execute_rw(struct nvmet_req *req)
>>    {
>>    	int sg_cnt = req->sg_cnt;
>> @@ -185,7 +215,8 @@ static void nvmet_bdev_execute_rw(struct nvmet_req *req)
>>    	bio->bi_end_io = nvmet_bio_done;
>>    	bio->bi_opf = op;
>>
>> -	blk_start_plug(&plug);
>> +	if (!req->poll)
>> +		blk_start_plug(&plug);
>>    	for_each_sg(req->sg, sg, req->sg_cnt, i) {
>>    		while (bio_add_page(bio, sg_page(sg), sg->length, sg->offset)
>>    				!= sg->length) {
>> @@ -204,8 +235,16 @@ static void nvmet_bdev_execute_rw(struct nvmet_req *req)
>>    		sg_cnt--;
>>    	}
>>
>> -	submit_bio(bio);
>> -	blk_finish_plug(&plug);
>> +	req->b.last_bio = bio;
>> +	if (req->poll)
>> +		req->b.last_bio->bi_opf |= REQ_HIPRI;
>> +
>> +	req->b.cookie = submit_bio(bio);
>> +
>> +	nvmet_req_prep_poll(req);
>> +	nvmet_req_issue_poll(req);
>> +	if (!req->poll)
>> +		blk_finish_plug(&plug);
>>    }
>>
>>    static void nvmet_bdev_execute_flush(struct nvmet_req *req)
>> @@ -330,15 +369,19 @@ u16 nvmet_bdev_parse_io_cmd(struct nvmet_req *req)
>>    	switch (cmd->common.opcode) {
>>    	case nvme_cmd_read:
>>    	case nvme_cmd_write:
>> +		req->poll = req->ns->poll;
>>    		req->execute = nvmet_bdev_execute_rw;
>>    		return 0;
>>    	case nvme_cmd_flush:
>> +		req->poll = false;
>
> should be done in some general place for req initialization.
>
>

This needs to be done here for better redability, since it
depends on the 2 factors with backend support and user setting.

>>    		req->execute = nvmet_bdev_execute_flush;
>>    		return 0;
>>    	case nvme_cmd_dsm:
>> +		req->poll = false;
>>    		req->execute = nvmet_bdev_execute_dsm;
>>    		return 0;
>>    	case nvme_cmd_write_zeroes:
>> +		req->poll = false;
>>    		req->execute = nvmet_bdev_execute_write_zeroes;
>>    		return 0;
>>    	default:
>> diff --git a/drivers/nvme/target/io-poll.c b/drivers/nvme/target/io-poll.c
>> new file mode 100644
>> index 000000000000..175c939c22ff
>> --- /dev/null
>> +++ b/drivers/nvme/target/io-poll.c
>> @@ -0,0 +1,165 @@
>> +#include <linux/blkdev.h>
>> +#include <linux/module.h>
>> +#include <linux/sched/signal.h>
>> +#include <linux/kthread.h>
>> +#include <uapi/linux/sched/types.h>
>> +
>> +#include "nvmet.h"
>> +#define THREAD_PER_CPU	(num_online_cpus() * 2)
>> +
>> +static int nvmet_poll_thread(void *data);
>> +
>> +int nvmet_ns_start_poll(struct nvmet_ns *ns)
>> +{
>> +	struct nvmet_poll_data *t;
>> +	int ret = 0;
>> +	int i;
>> +
>> +	t = kzalloc(sizeof(*t) * THREAD_PER_CPU, GFP_KERNEL);
>> +	if (!t) {
>> +		ret = -ENOMEM;
>> +		goto out;
>> +	}
>> +
>> +	for (i = 0; i < THREAD_PER_CPU; i++) {
>> +		init_completion(&t[i].thread_complete);
>> +		init_waitqueue_head(&t[i].poll_waitq);
>> +		INIT_LIST_HEAD(&t[i].list);
>> +		INIT_LIST_HEAD(&t[i].done);
>> +		mutex_init(&t[i].list_lock);
>> +		t[i].id = i;
>> +
>> +		t[i].thread = kthread_create(nvmet_poll_thread, &t[i],
>> +					     "nvmet_poll_thread%s/%d",
>> +					     ns->device_path, i);
>> +
>> +		if (IS_ERR(t[i].thread)) {
>> +			ret = PTR_ERR(t[i].thread);
>> +			goto err;
>> +		}
>> +
>> +		kthread_bind(t[i].thread, i % num_online_cpus());
>> +		wake_up_process(t[i].thread);
>> +		wait_for_completion(&t[i].thread_complete);
>> +	}
>> +
>> +	ns->t = t;
>> +out:
>> +	return ret;
>> +err:
>> +	nvmet_ns_stop_poll(ns);
>> +	goto out;
>> +}
>> +
>> +void nvmet_ns_stop_poll(struct nvmet_ns *ns)
>> +{
>> +	struct nvmet_poll_data *t = ns->t;
>> +	int i;
>> +
>> +	for (i = 0; i < THREAD_PER_CPU; i++) {
>> +		if (!t[i].thread)
>> +			continue;
>> +
>> +		if (wq_has_sleeper(&t[i].poll_waitq))
>> +			wake_up(&t[i].poll_waitq);
>> +		kthread_park(t[i].thread);
>> +		kthread_stop(t[i].thread);
>> +	}
>> +}
>> +
>> +static void nvmet_poll(struct nvmet_poll_data *t)
>> +{
>> +	struct nvmet_req *req, *tmp;
>> +
>> +	lockdep_assert_held(&t->list_lock);
>> +
>> +	list_for_each_entry_safe(req, tmp, &t->list, poll_entry) {
>> +
>> +		if (completion_done(&req->wait)) {
>> +			list_move_tail(&req->poll_entry, &t->done);
>> +			continue;
>> +		}
>> +
>> +		if (!list_empty(&t->done))
>> +			break;
>> +
>> +		list_del(&req->poll_entry);
>> +		mutex_unlock(&t->list_lock);
>> +		nvmet_req_poll_complete(req);
>> +		mutex_lock(&t->list_lock);
>> +	}
>> +	mutex_unlock(&t->list_lock);
>> +	/*
>> +	 * In future we can also add batch timeout or nr request to complete.
>> +	 */
>> +	while (!list_empty(&t->done)) {
>> +		/*
>> +		 * We lock and unlock for t->list which gurantee progress of
>> +		 * nvmet_xxx_rw_execute() when under pressure while we complete
>> +		 * the request.
>> +		 */
>> +		req = list_first_entry(&t->done, struct nvmet_req, poll_entry);
>> +		list_del(&req->poll_entry);
>> +		nvmet_req_done(req);
>> +	}
>> +
>> +	mutex_lock(&t->list_lock);
>> +}
>> +
>> +static int nvmet_poll_thread(void *data)
>> +{
>> +	struct nvmet_poll_data *t = (struct nvmet_poll_data *) data;
>> +	DEFINE_WAIT(wait);
>> +
>> +	complete(&t->thread_complete);
>> +
>> +	while (!kthread_should_park()) {
>> +
>> +		mutex_lock(&t->list_lock);
>> +		while (!list_empty(&t->list) && !need_resched())
>> +			nvmet_poll(t);
>> +		mutex_unlock(&t->list_lock);
>> +
>> +		prepare_to_wait(&t->poll_waitq, &wait, TASK_INTERRUPTIBLE);
>> +		if (signal_pending(current))
>> +			flush_signals(current);
>> +		smp_mb();
>> +		schedule();
>> +
>> +		finish_wait(&t->poll_waitq, &wait);
>> +	}
>> +
>> +	kthread_parkme();
>> +	return 0;
>> +}
>> +
>> +inline void nvmet_req_prep_poll(struct nvmet_req *req)
>> +{
>> +	if (!req->poll)
>> +		return;
>> +
>> +	init_completion(&req->wait);
>> +	req->t = &req->ns->t[smp_processor_id()];
>> +}
>> +
>> +inline void nvmet_req_issue_poll(struct nvmet_req *req)
>> +{
>> +	if (!req->poll)
>> +		return;
>> +
>> +	while (!mutex_trylock(&req->t->list_lock)) {
>> +		if (req->t->id < num_online_cpus())
>> +			req->t = &req->ns->t[req->t->id + num_online_cpus()];
>> +		else
>> +			req->t = &req->ns->t[req->t->id - num_online_cpus()];
>> +	}
>> +
>> +	if (completion_done(&req->wait))
>> +		list_add(&req->poll_entry, &req->t->list);
>> +	else
>> +		list_add_tail(&req->poll_entry, &req->t->list);
>> +	mutex_unlock(&req->t->list_lock);
>> +
>> +	if (wq_has_sleeper(&req->t->poll_waitq))
>> +		wake_up(&req->t->poll_waitq);
>> +}
>> diff --git a/drivers/nvme/target/nvmet.h b/drivers/nvme/target/nvmet.h
>> index 46df45e837c9..ef2919e23e0b 100644
>> --- a/drivers/nvme/target/nvmet.h
>> +++ b/drivers/nvme/target/nvmet.h
>> @@ -49,11 +49,22 @@
>>    #define IPO_IATTR_CONNECT_SQE(x)	\
>>    	(cpu_to_le32(offsetof(struct nvmf_connect_command, x)))
>>
>> +struct nvmet_poll_data {
>> +	struct completion		thread_complete;
>> +	wait_queue_head_t		poll_waitq;
>> +	struct mutex			list_lock;
>> +	struct task_struct		*thread;
>> +	struct list_head		list;
>> +	struct list_head		done;
>> +	unsigned int			id;
>> +};
>> +
>>    struct nvmet_ns {
>>    	struct list_head	dev_link;
>>    	struct percpu_ref	ref;
>>    	struct block_device	*bdev;
>>    	struct file		*file;
>> +	struct nvmet_poll_data	*t;
>>    	bool			readonly;
>>    	u32			nsid;
>>    	u32			blksize_shift;
>> @@ -63,6 +74,8 @@ struct nvmet_ns {
>>    	u32			anagrpid;
>>
>>    	bool			buffered_io;
>> +	bool			use_poll;
>> +	bool			poll;
>>    	bool			enabled;
>>    	struct nvmet_subsys	*subsys;
>>    	const char		*device_path;
>> @@ -292,9 +305,15 @@ struct nvmet_req {
>>    	struct nvmet_ns		*ns;
>>    	struct scatterlist	*sg;
>>    	struct bio_vec		inline_bvec[NVMET_MAX_INLINE_BIOVEC];
>> +	struct completion	wait;
>> +	bool			poll;
>> +	struct nvmet_poll_data  *t;
>> +	struct list_head	poll_entry;
>>    	union {
>>    		struct {
>> -			struct bio      inline_bio;
>> +			struct bio		inline_bio;
>> +			blk_qc_t		cookie;
>> +			struct bio		*last_bio;
>>    		} b;
>>    		struct {
>>    			bool			mpool_alloc;
>> @@ -442,6 +461,16 @@ void nvmet_subsys_disc_changed(struct nvmet_subsys *subsys,
>>    void nvmet_add_async_event(struct nvmet_ctrl *ctrl, u8 event_type,
>>    		u8 event_info, u8 log_page);
>>
>> +int nvmet_ns_start_poll(struct nvmet_ns *ns);
>> +void nvmet_ns_stop_poll(struct nvmet_ns *ns);
>> +void nvmet_req_prep_poll(struct nvmet_req *req);
>> +void nvmet_req_issue_poll(struct nvmet_req *req);
>> +
>> +void nvmet_req_poll_complete(struct nvmet_req *req);
>> +void nvmet_bdev_poll_complete(struct nvmet_req *req);
>> +void nvmet_bdev_req_complete(struct nvmet_req *req);
>> +void nvmet_req_done(struct nvmet_req *req);
>> +
>>    #define NVMET_QUEUE_SIZE	1024
>>    #define NVMET_NR_QUEUES		128
>>    #define NVMET_MAX_CMD		NVMET_QUEUE_SIZE
>


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  reply	other threads:[~2020-01-21 19:22 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-12-10  6:25 [RFC PATCH 0/2] nvmet: add " Chaitanya Kulkarni
2019-12-10  6:25 ` [RFC PATCH 1/2] nvmet: add bdev-ns " Chaitanya Kulkarni
2020-01-20 12:52   ` Max Gurtovoy
2020-01-21 19:22     ` Chaitanya Kulkarni [this message]
2020-01-23 14:23       ` Max Gurtovoy
2020-01-30 18:19         ` Chaitanya Kulkarni
2019-12-10  6:25 ` [RFC PATCH 2/2] nvmet: add file-ns " Chaitanya Kulkarni
2019-12-12  1:01 ` [RFC PATCH 0/2] nvmet: add " Sagi Grimberg
2019-12-12  5:44   ` Chaitanya Kulkarni
2019-12-12 20:32     ` Sagi Grimberg
2020-01-20  5:13       ` Chaitanya Kulkarni
2020-01-20  4:48   ` Chaitanya Kulkarni

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