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nvme: APST improvements (for 4.12, perhaps)

PATCH In review Andy Lutomirski 3 participants 9 messages Apr 21, 2017 – Apr 25, 2017 NVMe

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Andy Lutomirski

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#0 lore raw

cover nvme: APST improvements (for 4.12, perhaps)

Hi all-

These are APST improvements for 4.12 or so. The first one fixes a buggy comment. The second makes debugging easier. The third makes it possible to force APST on despite quirks.

Andy Lutomirski (3):
nvme: Fix APST comment
nvme: Display raw APST configuration via DYNAMIC_DEBUG
nvme: Add nvme_core.force_apst to ignore the NO_APST quirk

 drivers/nvme/host/core.c | 38 ++++++++++++++++++++++++++++++++++++--
 1 file changed, 36 insertions(+), 2 deletions(-)
Signature · 1 line
2.9.3
author
#1 lore raw

PATCH 1/3 nvme: Fix APST comment

There was a typo in the description of the timeout heuristic.

Signed-off-by Andy Lutomirski <luto at kernel.org>
---
 drivers/nvme/host/core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
drivers/nvme/host/core.c +1 -1
index eeb409c287b8..b0c692a14e9b 100644
@@ -1267,7 +1267,7 @@ static void nvme_configure_apst(struct nvme_ctrl *ctrl)
 	 * heuristic: we are willing to spend at most 2% of the time
 	 * transitioning between power states.  Therefore, when running
 	 * in any given state, we will enter the next lower-power
-	 * non-operational state after waiting 100 * (enlat + exlat)
+	 * non-operational state after waiting 50 * (enlat + exlat)
 	 * microseconds, as long as that state's total latency is under
 	 * the requested maximum latency.
 	 *
Signature · 1 line
2.9.3
author
#3 lore raw

PATCH 2/3 nvme: Display raw APST configuration via DYNAMIC_DEBUG

In reply to Andy Lutomirski

Debugging APST is currently a bit of a pain. This gives optional simple log messages that describe the APST state.

The easiest way to use this is probably with the nvme_core.dyndbg=+p module parameter.

Signed-off-by Andy Lutomirski <luto at kernel.org>
---
 drivers/nvme/host/core.c | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)
drivers/nvme/host/core.c +16 -0
index b0c692a14e9b..05ba4f8bb73b 100644
@@ -1278,6 +1278,8 @@ static void nvme_configure_apst(struct nvme_ctrl *ctrl)
 
 	unsigned apste;
 	struct nvme_feat_auto_pst *table;
+	u64 max_lat_us = 0;
+	int max_ps = -1;
 	int ret;
 
 	/*

@@ -1299,6 +1301,7 @@ static void nvme_configure_apst(struct nvme_ctrl *ctrl)
 	if (ctrl->ps_max_latency_us == 0) {
 		/* Turn off APST. */
 		apste = 0;
+		dev_dbg(ctrl->device, "APST disabled\n");
 	} else {
 		__le64 target = cpu_to_le64(0);
 		int state;

@@ -1348,9 +1351,22 @@ static void nvme_configure_apst(struct nvme_ctrl *ctrl)
 
 			target = cpu_to_le64((state << 3) |
 					     (transition_ms << 8));
+
+			if (max_ps == -1)
+				max_ps = state;
+
+			if (total_latency_us > max_lat_us)
+				max_lat_us = total_latency_us;
 		}
 
 		apste = 1;
+
+		if (max_ps == -1) {
+			dev_dbg(ctrl->device, "APST enabled but no non-operational states are available\n");
+		} else {
+			dev_dbg(ctrl->device, "APST enabled: max PS = %d, max round-trip latency = %lluus, table = %*phN\n",
+				max_ps, max_lat_us, (int)sizeof(*table), table);
+		}
 	}
 
 	ret = nvme_set_features(ctrl, NVME_FEAT_AUTO_PST, apste,
Signature · 1 line
2.9.3
author
#5 lore raw

PATCH 3/3 nvme: Add nvme_core.force_apst to ignore the NO_APST quirk

In reply to Andy Lutomirski

We're probably going to be stuck quirking APST off on an over-broad range of devices for 4.11. Let's make it easy to override the quirk for testing.

Signed-off-by Andy Lutomirski <luto at kernel.org>
---
 drivers/nvme/host/core.c | 20 +++++++++++++++++++-
 1 file changed, 19 insertions(+), 1 deletion(-)
drivers/nvme/host/core.c +19 -1
index 05ba4f8bb73b..5249027a76ca 100644
@@ -62,6 +62,10 @@ module_param(default_ps_max_latency_us, ulong, 0644);
 MODULE_PARM_DESC(default_ps_max_latency_us,
 		 "max power saving latency for new devices; use PM QOS to change per device");
 
+static bool force_apst;
+module_param(force_apst, bool, 0644);
+MODULE_PARM_DESC(force_apst, "allow APST for newly enumerated devices even if quirked off");
+
 static LIST_HEAD(nvme_ctrl_list);
 static DEFINE_SPINLOCK(dev_list_lock);
 

@@ -1504,6 +1508,11 @@ int nvme_init_identify(struct nvme_ctrl *ctrl)
 		}
 	}
 
+	if (force_apst && (ctrl->quirks & NVME_QUIRK_NO_DEEPEST_PS)) {
+		dev_warn(ctrl->dev, "forcibly allowing all power states due to nvme_core.force_apst -- use at your own risk\n");
+		ctrl->quirks &= ~NVME_QUIRK_NO_DEEPEST_PS;
+	}
+
 	ctrl->oacs = le16_to_cpu(id->oacs);
 	ctrl->vid = le16_to_cpu(id->vid);
 	ctrl->oncs = le16_to_cpup(&id->oncs);

@@ -1526,7 +1535,16 @@ int nvme_init_identify(struct nvme_ctrl *ctrl)
 
 	ctrl->npss = id->npss;
 	prev_apsta = ctrl->apsta;
-	ctrl->apsta = (ctrl->quirks & NVME_QUIRK_NO_APST) ? 0 : id->apsta;
+	if (ctrl->quirks & NVME_QUIRK_NO_APST) {
+		if (force_apst && id->apsta) {
+			dev_warn(ctrl->dev, "forcibly allowing APST due to nvme_core.force_apst -- use at your own risk\n");
+			ctrl->apsta = 1;
+		} else {
+			ctrl->apsta = 0;
+		}
+	} else {
+		ctrl->apsta = id->apsta;
+	}
 	memcpy(ctrl->psd, id->psd, sizeof(ctrl->psd));
 
 	if (ctrl->ops->is_fabrics) {
Signature · 1 line
2.9.3
maintainer Reviewed-by on v1 1/3
#2 lore raw

Re: [PATCH 1/3] nvme: Fix APST comment

In reply to Andy Lutomirski
Quoted 1 line · Andy Lutomirski

There was a typo in the description of the timeout heuristic.

Looks good,

Reviewed-by Christoph Hellwig <hch at lst.de>
maintainer
#7 lore raw
In reply to Andy Lutomirski
Quoted 6 lines · Andy Lutomirski

Hi all-

These are APST improvements for 4.12 or so. The first one fixes a buggy comment. The second makes debugging easier. The third makes it possible to force APST on despite quirks.

Quoted 7 lines

Andy Lutomirski (3):
nvme: Fix APST comment
nvme: Display raw APST configuration via DYNAMIC_DEBUG
nvme: Add nvme_core.force_apst to ignore the NO_APST quirk

 drivers/nvme/host/core.c | 38 ++++++++++++++++++++++++++++++++++++--
 1 file changed, 36 insertions(+), 2 deletions(-)

I have added these for 4.12, thanks Andy.

Signature · 1 line
Jens Axboe
maintainer
#8 lore raw
Quoted 1 line · Jens Axboe

I have added these for 4.12, thanks Andy.

This shouldn't conflict with what we've queued up in the nvme tree so we should be ok..