[PATCH v2 1/2] powerpc/papr_scm: Fetch nvdimm performance stats from PHYP
Vaibhav Jain
vaibhav at linux.ibm.com
Wed Jul 1 23:35:09 AEST 2020
Update papr_scm.c to query dimm performance statistics from PHYP via
H_SCM_PERFORMANCE_STATS hcall and export them to user-space as PAPR
specific NVDIMM attribute 'perf_stats' in sysfs. The patch also
provide a sysfs ABI documentation for the stats being reported and
their meanings.
During NVDIMM probe time in papr_scm_nvdimm_init() a special variant
of H_SCM_PERFORMANCE_STATS hcall is issued to check if collection of
performance statistics is supported or not. If successful then a PHYP
returns a maximum possible buffer length needed to read all
performance stats. This returned value is stored in a per-nvdimm
attribute 'stat_buffer_len'.
The layout of request buffer for reading NVDIMM performance stats from
PHYP is defined in 'struct papr_scm_perf_stats' and 'struct
papr_scm_perf_stat'. These structs are used in newly introduced
drc_pmem_query_stats() that issues the H_SCM_PERFORMANCE_STATS hcall.
The sysfs access function perf_stats_show() uses value
'stat_buffer_len' to allocate a buffer large enough to hold all
possible NVDIMM performance stats and passes it to
drc_pmem_query_stats() to populate. Finally statistics reported in the
buffer are formatted into the sysfs access function output buffer.
Signed-off-by: Vaibhav Jain <vaibhav at linux.ibm.com>
---
Changelog:
v2:
* Fixed a bug in drc_pmem_query_stats() that was passing a NULL pointer
to virt_to_pfn() [ Ira ]
* Updated 'struct papr_scm_perf_stats' and 'struct papr_scm_perf_stat'
to use big-endian types. [ Aneesh ]
* s/len_stat_buffer/stat_buffer_len/ [ Aneesh ]
* s/statistics_id/stat_id/ , s/statistics_val/stat_val/ [ Aneesh ]
* Conversion from Big endian to cpu endian happens later rather than
just after its fetched from PHYP.
* Changed a log statement to unambiguously report dimm performance
stats are not available for the given nvdimm [ Ira ]
* Restructed some code to handle error case first [ Ira ]
---
Documentation/ABI/testing/sysfs-bus-papr-pmem | 27 ++++
arch/powerpc/platforms/pseries/papr_scm.c | 134 ++++++++++++++++++
2 files changed, 161 insertions(+)
diff --git a/Documentation/ABI/testing/sysfs-bus-papr-pmem b/Documentation/ABI/testing/sysfs-bus-papr-pmem
index 5b10d036a8d4..c1a67275c43f 100644
--- a/Documentation/ABI/testing/sysfs-bus-papr-pmem
+++ b/Documentation/ABI/testing/sysfs-bus-papr-pmem
@@ -25,3 +25,30 @@ Description:
NVDIMM have been scrubbed.
* "locked" : Indicating that NVDIMM contents cant
be modified until next power cycle.
+
+What: /sys/bus/nd/devices/nmemX/papr/perf_stats
+Date: May, 2020
+KernelVersion: v5.9
+Contact: linuxppc-dev <linuxppc-dev at lists.ozlabs.org>, linux-nvdimm at lists.01.org,
+Description:
+ (RO) Report various performance stats related to papr-scm NVDIMM
+ device. Each stat is reported on a new line with each line
+ composed of a stat-identifier followed by it value. Below are
+ currently known dimm performance stats which are reported:
+
+ * "CtlResCt" : Controller Reset Count
+ * "CtlResTm" : Controller Reset Elapsed Time
+ * "PonSecs " : Power-on Seconds
+ * "MemLife " : Life Remaining
+ * "CritRscU" : Critical Resource Utilization
+ * "HostLCnt" : Host Load Count
+ * "HostSCnt" : Host Store Count
+ * "HostSDur" : Host Store Duration
+ * "HostLDur" : Host Load Duration
+ * "MedRCnt " : Media Read Count
+ * "MedWCnt " : Media Write Count
+ * "MedRDur " : Media Read Duration
+ * "MedWDur " : Media Write Duration
+ * "CchRHCnt" : Cache Read Hit Count
+ * "CchWHCnt" : Cache Write Hit Count
+ * "FastWCnt" : Fast Write Count
\ No newline at end of file
diff --git a/arch/powerpc/platforms/pseries/papr_scm.c b/arch/powerpc/platforms/pseries/papr_scm.c
index 9c569078a09f..bde2433822b2 100644
--- a/arch/powerpc/platforms/pseries/papr_scm.c
+++ b/arch/powerpc/platforms/pseries/papr_scm.c
@@ -62,6 +62,26 @@
PAPR_PMEM_HEALTH_FATAL | \
PAPR_PMEM_HEALTH_UNHEALTHY)
+#define PAPR_SCM_PERF_STATS_EYECATCHER __stringify(SCMSTATS)
+#define PAPR_SCM_PERF_STATS_VERSION 0x1
+
+/* Struct holding a single performance metric */
+struct papr_scm_perf_stat {
+ u8 stat_id[8];
+ __be64 stat_val;
+} __packed;
+
+/* Struct exchanged between kernel and PHYP for fetching drc perf stats */
+struct papr_scm_perf_stats {
+ u8 eye_catcher[8];
+ /* Should be PAPR_SCM_PERF_STATS_VERSION */
+ __be32 stats_version;
+ /* Number of stats following */
+ __be32 num_statistics;
+ /* zero or more performance matrics */
+ struct papr_scm_perf_stat scm_statistic[];
+} __packed;
+
/* private struct associated with each region */
struct papr_scm_priv {
struct platform_device *pdev;
@@ -89,6 +109,9 @@ struct papr_scm_priv {
/* Health information for the dimm */
u64 health_bitmap;
+
+ /* length of the stat buffer as expected by phyp */
+ size_t stat_buffer_len;
};
static int drc_pmem_bind(struct papr_scm_priv *p)
@@ -194,6 +217,65 @@ static int drc_pmem_query_n_bind(struct papr_scm_priv *p)
return drc_pmem_bind(p);
}
+/*
+ * Query the Dimm performance stats from PHYP and copy them (if returned) to
+ * provided struct papr_scm_perf_stats instance 'stats' of 'size' in bytes.
+ * The value of R4 is copied to 'out' if the pointer is provided.
+ */
+static int drc_pmem_query_stats(struct papr_scm_priv *p,
+ struct papr_scm_perf_stats *buff_stats,
+ size_t size, unsigned int num_stats,
+ uint64_t *out)
+{
+ unsigned long ret[PLPAR_HCALL_BUFSIZE];
+ s64 rc;
+
+ /* Setup the out buffer */
+ if (buff_stats) {
+ memcpy(buff_stats->eye_catcher,
+ PAPR_SCM_PERF_STATS_EYECATCHER, 8);
+ buff_stats->stats_version =
+ cpu_to_be32(PAPR_SCM_PERF_STATS_VERSION);
+ buff_stats->num_statistics =
+ cpu_to_be32(num_stats);
+ } else {
+ /* In case of no out buffer ignore the size */
+ size = 0;
+ }
+
+ /*
+ * Do the HCALL asking PHYP for info and if R4 was requested
+ * return its value in 'out' variable.
+ */
+ rc = plpar_hcall(H_SCM_PERFORMANCE_STATS, ret, p->drc_index,
+ buff_stats ? virt_to_phys(buff_stats) : 0,
+ size);
+ if (out)
+ *out = ret[0];
+
+ if (rc == H_PARTIAL) {
+ dev_err(&p->pdev->dev,
+ "Unknown performance stats, Err:0x%016lX\n", ret[0]);
+ return -ENOENT;
+ } else if (rc != H_SUCCESS) {
+ dev_err(&p->pdev->dev,
+ "Failed to query performance stats, Err:%lld\n", rc);
+ return -EIO;
+ }
+
+ /* Successfully fetched the requested stats from phyp */
+ if (size != 0)
+ dev_dbg(&p->pdev->dev,
+ "Performance stats returned %d stats\n",
+ be32_to_cpu(buff_stats->num_statistics));
+ else
+ /* Handle case where stat buffer size was requested */
+ dev_dbg(&p->pdev->dev,
+ "Performance stats size %ld\n", ret[0]);
+
+ return 0;
+}
+
/*
* Issue hcall to retrieve dimm health info and populate papr_scm_priv with the
* health information.
@@ -631,6 +713,48 @@ static int papr_scm_ndctl(struct nvdimm_bus_descriptor *nd_desc,
return 0;
}
+static ssize_t perf_stats_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ int index, rc;
+ struct seq_buf s;
+ struct papr_scm_perf_stat *stat;
+ struct papr_scm_perf_stats *stats;
+ struct nvdimm *dimm = to_nvdimm(dev);
+ struct papr_scm_priv *p = nvdimm_provider_data(dimm);
+
+ if (!p->stat_buffer_len)
+ return -ENOENT;
+
+ /* Allocate the buffer for phyp where stats are written */
+ stats = kzalloc(p->stat_buffer_len, GFP_KERNEL);
+ if (!stats)
+ return -ENOMEM;
+
+ /* Ask phyp to return all dimm perf stats */
+ rc = drc_pmem_query_stats(p, stats, p->stat_buffer_len, 0, NULL);
+ if (rc)
+ goto free_stats;
+ /*
+ * Go through the returned output buffer and print stats and
+ * values. Since stat_id is essentially a char string of
+ * 8 bytes, simply use the string format specifier to print it.
+ */
+ seq_buf_init(&s, buf, PAGE_SIZE);
+ for (index = 0, stat = stats->scm_statistic;
+ index < be32_to_cpu(stats->num_statistics);
+ ++index, ++stat) {
+ seq_buf_printf(&s, "%.8s = 0x%016llX\n",
+ stat->stat_id,
+ be64_to_cpu(stat->stat_val));
+ }
+
+free_stats:
+ kfree(stats);
+ return rc ? rc : seq_buf_used(&s);
+}
+DEVICE_ATTR_RO(perf_stats);
+
static ssize_t flags_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
@@ -676,6 +800,7 @@ DEVICE_ATTR_RO(flags);
/* papr_scm specific dimm attributes */
static struct attribute *papr_nd_attributes[] = {
&dev_attr_flags.attr,
+ &dev_attr_perf_stats.attr,
NULL,
};
@@ -696,6 +821,7 @@ static int papr_scm_nvdimm_init(struct papr_scm_priv *p)
struct nd_region_desc ndr_desc;
unsigned long dimm_flags;
int target_nid, online_nid;
+ u64 stat_size;
p->bus_desc.ndctl = papr_scm_ndctl;
p->bus_desc.module = THIS_MODULE;
@@ -759,6 +885,14 @@ static int papr_scm_nvdimm_init(struct papr_scm_priv *p)
dev_info(dev, "Region registered with target node %d and online node %d",
target_nid, online_nid);
+ /* Try retriving the stat buffer and see if its supported */
+ if (!drc_pmem_query_stats(p, NULL, 0, 0, &stat_size)) {
+ p->stat_buffer_len = (size_t)stat_size;
+ dev_dbg(&p->pdev->dev, "Max perf-stat size %lu-bytes\n",
+ p->stat_buffer_len);
+ } else {
+ dev_info(&p->pdev->dev, "Dimm performance stats unavailable\n");
+ }
return 0;
err: nvdimm_bus_unregister(p->bus);
--
2.26.2
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