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powerpc/papr_scm: Fetch nvdimm performance stats from PHYP

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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@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200731064153.182203-2-vaibhav@linux.ibm.com
This commit is contained in:
Vaibhav Jain 2020-07-31 12:11:52 +05:30 committed by Michael Ellerman
parent d947fb4c96
commit 2d02bf835e
2 changed files with 177 additions and 0 deletions
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27
Documentation/ABI/testing/sysfs-bus-papr-pmem
View file

@ -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@lists.ozlabs.org>, linux-nvdimm@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

150
arch/powerpc/platforms/pseries/papr_scm.c
View file

@ -64,6 +64,26 @@
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;
@ -92,6 +112,9 @@ 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 LIST_HEAD(papr_nd_regions);
@ -200,6 +223,79 @@ err_out:
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' that can hold atleast
* (num_stats + header) bytes.
* - If buff_stats == NULL the return value is the size in byes of the buffer
* needed to hold all supported performance-statistics.
* - If buff_stats != NULL and num_stats == 0 then we copy all known
* performance-statistics to 'buff_stat' and expect to be large enough to
* hold them.
* - if buff_stats != NULL and num_stats > 0 then copy the requested
* performance-statistics to buff_stats.
*/
static ssize_t drc_pmem_query_stats(struct papr_scm_priv *p,
struct papr_scm_perf_stats *buff_stats,
unsigned int num_stats)
{
unsigned long ret[PLPAR_HCALL_BUFSIZE];
size_t size;
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);
/*
* Calculate the buffer size based on num-stats provided
* or use the prefetched max buffer length
*/
if (num_stats)
/* Calculate size from the num_stats */
size = sizeof(struct papr_scm_perf_stats) +
num_stats * sizeof(struct papr_scm_perf_stat);
else
size = p->stat_buffer_len;
} else {
/* In case of no out buffer ignore the size */
size = 0;
}
/* Do the HCALL asking PHYP for info */
rc = plpar_hcall(H_SCM_PERFORMANCE_STATS, ret, p->drc_index,
buff_stats ? virt_to_phys(buff_stats) : 0,
size);
/* Check if the error was due to an unknown stat-id */
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;
} else if (!size) {
/* Handle case where stat buffer size was requested */
dev_dbg(&p->pdev->dev,
"Performance stats size %ld\n", ret[0]);
return ret[0];
}
/* Successfully fetched the requested stats from phyp */
dev_dbg(&p->pdev->dev,
"Performance stats returned %d stats\n",
be32_to_cpu(buff_stats->num_statistics));
return 0;
}
/*
* Issue hcall to retrieve dimm health info and populate papr_scm_priv with the
* health information.
@ -637,6 +733,48 @@ 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, 0);
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)
{
@ -682,6 +820,7 @@ 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,
};
@ -702,6 +841,7 @@ 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;
ssize_t stat_size;
p->bus_desc.ndctl = papr_scm_ndctl;
p->bus_desc.module = THIS_MODULE;
@ -769,6 +909,16 @@ static int papr_scm_nvdimm_init(struct papr_scm_priv *p)
list_add_tail(&p->region_list, &papr_nd_regions);
mutex_unlock(&papr_ndr_lock);
/* Try retriving the stat buffer and see if its supported */
stat_size = drc_pmem_query_stats(p, NULL, 0);
if (stat_size > 0) {
p->stat_buffer_len = 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);