[PATCH] nvme: remove support or stream based temperature hint

[PATCH] nvme: remove support or stream based temperature hint

[Christoph Hellwig]

This support was added for RocksDB, but RocksDB ended up not using it.
At the same time drives on the open marked (vs those build for OEMs
for non-Linux support) that actually support streams are extremly
rare.  Don't bloat the nvme driver for it.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 drivers/nvme/host/core.c | 143 ---------------------------------------
 1 file changed, 143 deletions(-)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index f8084ded69e50..61f29c59b14cf 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -77,10 +77,6 @@ module_param(apst_secondary_latency_tol_us, ulong, 0644);
 MODULE_PARM_DESC(apst_secondary_latency_tol_us,
 	"secondary APST latency tolerance in us");
 
-static bool streams;
-module_param(streams, bool, 0644);
-MODULE_PARM_DESC(streams, "turn on support for Streams write directives");
-
 /*
  * nvme_wq - hosts nvme related works that are not reset or delete
  * nvme_reset_wq - hosts nvme reset works
@@ -747,108 +743,6 @@ bool __nvme_check_ready(struct nvme_ctrl *ctrl, struct request *rq,
 }
 EXPORT_SYMBOL_GPL(__nvme_check_ready);
 
-static int nvme_toggle_streams(struct nvme_ctrl *ctrl, bool enable)
-{
-	struct nvme_command c = { };
-
-	c.directive.opcode = nvme_admin_directive_send;
-	c.directive.nsid = cpu_to_le32(NVME_NSID_ALL);
-	c.directive.doper = NVME_DIR_SND_ID_OP_ENABLE;
-	c.directive.dtype = NVME_DIR_IDENTIFY;
-	c.directive.tdtype = NVME_DIR_STREAMS;
-	c.directive.endir = enable ? NVME_DIR_ENDIR : 0;
-
-	return nvme_submit_sync_cmd(ctrl->admin_q, &c, NULL, 0);
-}
-
-static int nvme_disable_streams(struct nvme_ctrl *ctrl)
-{
-	return nvme_toggle_streams(ctrl, false);
-}
-
-static int nvme_enable_streams(struct nvme_ctrl *ctrl)
-{
-	return nvme_toggle_streams(ctrl, true);
-}
-
-static int nvme_get_stream_params(struct nvme_ctrl *ctrl,
-				  struct streams_directive_params *s, u32 nsid)
-{
-	struct nvme_command c = { };
-
-	memset(s, 0, sizeof(*s));
-
-	c.directive.opcode = nvme_admin_directive_recv;
-	c.directive.nsid = cpu_to_le32(nsid);
-	c.directive.numd = cpu_to_le32(nvme_bytes_to_numd(sizeof(*s)));
-	c.directive.doper = NVME_DIR_RCV_ST_OP_PARAM;
-	c.directive.dtype = NVME_DIR_STREAMS;
-
-	return nvme_submit_sync_cmd(ctrl->admin_q, &c, s, sizeof(*s));
-}
-
-static int nvme_configure_directives(struct nvme_ctrl *ctrl)
-{
-	struct streams_directive_params s;
-	u16 nssa;
-	int ret;
-
-	if (!(ctrl->oacs & NVME_CTRL_OACS_DIRECTIVES))
-		return 0;
-	if (!streams)
-		return 0;
-
-	ret = nvme_enable_streams(ctrl);
-	if (ret)
-		return ret;
-
-	ret = nvme_get_stream_params(ctrl, &s, NVME_NSID_ALL);
-	if (ret)
-		goto out_disable_stream;
-
-	nssa = le16_to_cpu(s.nssa);
-	if (nssa < BLK_MAX_WRITE_HINTS - 1) {
-		dev_info(ctrl->device, "too few streams (%u) available\n",
-					nssa);
-		/* this condition is not an error: streams are optional */
-		ret = 0;
-		goto out_disable_stream;
-	}
-
-	ctrl->nr_streams = min_t(u16, nssa, BLK_MAX_WRITE_HINTS - 1);
-	dev_info(ctrl->device, "Using %u streams\n", ctrl->nr_streams);
-	return 0;
-
-out_disable_stream:
-	nvme_disable_streams(ctrl);
-	return ret;
-}
-
-/*
- * Check if 'req' has a write hint associated with it. If it does, assign
- * a valid namespace stream to the write.
- */
-static void nvme_assign_write_stream(struct nvme_ctrl *ctrl,
-				     struct request *req, u16 *control,
-				     u32 *dsmgmt)
-{
-	enum rw_hint streamid = req->write_hint;
-
-	if (streamid == WRITE_LIFE_NOT_SET || streamid == WRITE_LIFE_NONE)
-		streamid = 0;
-	else {
-		streamid--;
-		if (WARN_ON_ONCE(streamid > ctrl->nr_streams))
-			return;
-
-		*control |= NVME_RW_DTYPE_STREAMS;
-		*dsmgmt |= streamid << 16;
-	}
-
-	if (streamid < ARRAY_SIZE(req->q->write_hints))
-		req->q->write_hints[streamid] += blk_rq_bytes(req) >> 9;
-}
-
 static inline void nvme_setup_flush(struct nvme_ns *ns,
 		struct nvme_command *cmnd)
 {
@@ -952,7 +846,6 @@ static inline blk_status_t nvme_setup_rw(struct nvme_ns *ns,
 		struct request *req, struct nvme_command *cmnd,
 		enum nvme_opcode op)
 {
-	struct nvme_ctrl *ctrl = ns->ctrl;
 	u16 control = 0;
 	u32 dsmgmt = 0;
 
@@ -975,9 +868,6 @@ static inline blk_status_t nvme_setup_rw(struct nvme_ns *ns,
 	cmnd->rw.apptag = 0;
 	cmnd->rw.appmask = 0;
 
-	if (req_op(req) == REQ_OP_WRITE && ctrl->nr_streams)
-		nvme_assign_write_stream(ctrl, req, &control, &dsmgmt);
-
 	if (ns->ms) {
 		/*
 		 * If formated with metadata, the block layer always provides a
@@ -1696,9 +1586,6 @@ static void nvme_config_discard(struct gendisk *disk, struct nvme_ns *ns)
 		return;
 	}
 
-	if (ctrl->nr_streams && ns->sws && ns->sgs)
-		size *= ns->sws * ns->sgs;
-
 	BUILD_BUG_ON(PAGE_SIZE / sizeof(struct nvme_dsm_range) <
 			NVME_DSM_MAX_RANGES);
 
@@ -1724,31 +1611,6 @@ static bool nvme_ns_ids_equal(struct nvme_ns_ids *a, struct nvme_ns_ids *b)
 		a->csi == b->csi;
 }
 
-static int nvme_setup_streams_ns(struct nvme_ctrl *ctrl, struct nvme_ns *ns,
-				 u32 *phys_bs, u32 *io_opt)
-{
-	struct streams_directive_params s;
-	int ret;
-
-	if (!ctrl->nr_streams)
-		return 0;
-
-	ret = nvme_get_stream_params(ctrl, &s, ns->head->ns_id);
-	if (ret)
-		return ret;
-
-	ns->sws = le32_to_cpu(s.sws);
-	ns->sgs = le16_to_cpu(s.sgs);
-
-	if (ns->sws) {
-		*phys_bs = ns->sws * (1 << ns->lba_shift);
-		if (ns->sgs)
-			*io_opt = *phys_bs * ns->sgs;
-	}
-
-	return 0;
-}
-
 static int nvme_configure_metadata(struct nvme_ns *ns, struct nvme_id_ns *id)
 {
 	struct nvme_ctrl *ctrl = ns->ctrl;
@@ -1841,7 +1703,6 @@ static void nvme_update_disk_info(struct gendisk *disk,
 	blk_integrity_unregister(disk);
 
 	atomic_bs = phys_bs = bs;
-	nvme_setup_streams_ns(ns->ctrl, ns, &phys_bs, &io_opt);
 	if (id->nabo == 0) {
 		/*
 		 * Bit 1 indicates whether NAWUPF is defined for this namespace
@@ -3133,10 +2994,6 @@ int nvme_init_ctrl_finish(struct nvme_ctrl *ctrl)
 	if (ret < 0)
 		return ret;
 
-	ret = nvme_configure_directives(ctrl);
-	if (ret < 0)
-		return ret;
-
 	ret = nvme_configure_acre(ctrl);
 	if (ret < 0)
 		return ret;
-- 
2.30.2

Re: [PATCH] nvme: remove support or stream based temperature hint

[Jens Axboe]

On 3/3/22 3:50 AM, Christoph Hellwig wrote:
> This support was added for RocksDB, but RocksDB ended up not using it.
> At the same time drives on the open marked (vs those build for OEMs
> for non-Linux support) that actually support streams are extremly
> rare.  Don't bloat the nvme driver for it.

Acked-by: Jens Axboe <axboe@kernel.dk>

-- 
Jens Axboe

Re: [PATCH] nvme: remove support or stream based temperature hint

[Keith Busch]

On Thu, Mar 03, 2022 at 01:50:49PM +0300, Christoph Hellwig wrote:
> This support was added for RocksDB, but RocksDB ended up not using it.
> At the same time drives on the open marked (vs those build for OEMs
> for non-Linux support) that actually support streams are extremly
> rare.  Don't bloat the nvme driver for it.

Fine with me. It looks like the early interest in streams never really
materialized, so it's unlikely we'll hear any complaints. 

You can remove nr_streams from 'struct nvme_ctrl' while you're at it.

Reviewed-by: Keith Busch <kbusch@kernel.org>

And without nvme, there doesn't appear to be a real user for the
write_hint anymore. All you can really do with it now is prevent
merging, which doesn't seem useful.

Re: [PATCH] nvme: remove support or stream based temperature hint

[Jens Axboe]

On 3/3/22 7:42 AM, Keith Busch wrote:
> On Thu, Mar 03, 2022 at 01:50:49PM +0300, Christoph Hellwig wrote:
>> This support was added for RocksDB, but RocksDB ended up not using it.
>> At the same time drives on the open marked (vs those build for OEMs
>> for non-Linux support) that actually support streams are extremly
>> rare.  Don't bloat the nvme driver for it.
> 
> Fine with me. It looks like the early interest in streams never really
> materialized, so it's unlikely we'll hear any complaints. 
> 
> You can remove nr_streams from 'struct nvme_ctrl' while you're at it.
> 
> Reviewed-by: Keith Busch <kbusch@kernel.org>
> 
> And without nvme, there doesn't appear to be a real user for the
> write_hint anymore. All you can really do with it now is prevent
> merging, which doesn't seem useful.

Yes, I would suggest that we just prune the write hint and just leave
the fcntl() ops as stubs as a followup patch.

-- 
Jens Axboe

Re: [PATCH] nvme: remove support or stream based temperature hint

[Christoph Hellwig]

On Thu, Mar 03, 2022 at 07:50:05AM -0700, Jens Axboe wrote:
> > And without nvme, there doesn't appear to be a real user for the
> > write_hint anymore. All you can really do with it now is prevent
> > merging, which doesn't seem useful.
> >
> 
> Yes, I would suggest that we just prune the write hint and just leave
> the fcntl() ops as stubs as a followup patch.

So we need to keep i_write_hint anyway for f2fs, but the block layer
removal is easy.  It has some conflicts with other work, what tree
would you like it against?