2d02bf835e
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
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.