96fd2e89fb
The user recently report a perf issue in the ICX platform, when test by
perf event “uncore_imc_x/cas_count_write”,the write bandwidth is always
very small (only 0.38MB/s), it is caused by the wrong "umask" for the
"cas_count_write" event. When double-checking, find "cas_count_read"
also is wrong.
The public document for ICX uncore:
3rd Gen Intel® Xeon® Processor Scalable Family, Codename Ice Lake,Uncore
Performance Monitoring Reference Manual, Revision 1.00, May 2021
On 2.4.7, it defines Unit Masks for CAS_COUNT:
RD b00001111
WR b00110000
So corrected both "cas_count_read" and "cas_count_write" for ICX.
Old settings:
hswep_uncore_imc_events
INTEL_UNCORE_EVENT_DESC(cas_count_read, "event=0x04,umask=0x03")
INTEL_UNCORE_EVENT_DESC(cas_count_write, "event=0x04,umask=0x0c")
New settings:
snr_uncore_imc_events
INTEL_UNCORE_EVENT_DESC(cas_count_read, "event=0x04,umask=0x0f")
INTEL_UNCORE_EVENT_DESC(cas_count_write, "event=0x04,umask=0x30")
Fixes: 2b3b76b5ec67 ("perf/x86/intel/uncore: Add Ice Lake server uncore support")
Signed-off-by: Zhengjun Xing <zhengjun.xing@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Adrian Hunter <adrian.hunter@intel.com>
Reviewed-by: Kan Liang <kan.liang@linux.intel.com>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20211223144826.841267-1-zhengjun.xing@linux.intel.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.