Re: [PATCH v4 1/2] powerpc/papr_scm: Fetch nvdimm performance stats from PHYP
Vaibhav Jain writes:
> 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
> ---
> Changelog:
>
> v4:
> * Fixed a build issue with this patch by moving a hunk from second
> patch in series to this patch. [ Aneesh ]
>
> 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'.
>
> 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 ,
> linux-nvd...@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 3d1235a76ba9..f37f3f70007d 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
[PATCH v4 1/2] powerpc/papr_scm: Fetch nvdimm performance stats from PHYP
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
---
Changelog:
v4:
* Fixed a build issue with this patch by moving a hunk from second
patch in series to this patch. [ Aneesh ]
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'.
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 ,
linux-nvd...@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 3d1235a76ba9..f37f3f70007d 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
