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 <vaib...@linux.ibm.com> --- Changelog: v3: * Updated drc_pmem_query_stats() to not require 'buff_size' and 'out' args to the function. Instead 'buff_size' is calculated from 'num_stats' and instead of populating 'R4' in arg 'out' the value is returned from the function in case 'R4' represents 'max-buffer-size'. [ Aneesh ] Resend: None v2: * 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 | 150 ++++++++++++++++++ 2 files changed, 177 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-...@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 \ 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 8fd441d32487..29cab86141d8 100644 --- a/arch/powerpc/platforms/pseries/papr_scm.c +++ b/arch/powerpc/platforms/pseries/papr_scm.c @@ -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; }; LIST_HEAD(papr_nd_regions); @@ -200,6 +223,79 @@ 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' 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, 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) { @@ -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); -- 2.26.2 _______________________________________________ Linux-nvdimm mailing list -- linux-nvdimm@lists.01.org To unsubscribe send an email to linux-nvdimm-le...@lists.01.org