linux-kernel - [RFC 0/5] x86/intel_rdt: Better diagnostics

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Date:   Mon, 18 Sep 2017 15:18:38 -0700
From:   "Luck, Tony" <tony.luck@...el.com>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     Tony Luck <tony.luck@...el.com>, linux-kernel@...r.kernel.org,
        Boris Petkov <bp@...e.de>, Fenghua Yu <fenghua.yu@...el.com>,
        Reinette Chatre <reinette.chatre@...el.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Vikas Shivappa <vikas.shivappa@...el.com>
Subject: [RFC 0/5] x86/intel_rdt: Better diagnostics

From: Tony Luck <tony.luck@...el.com>

Chatting online with Boris to diagnose why his test cases for RDT
weren't working, we came up with either a good idea (in which case
I credit Boris) or a dumb one (in which case this is all my fault).

The basic problem is that there aren't many good error codes for
a file system interface to pass back to the user.  I'd resisted
adding printk() calls because it is a pain to parse the console
log, doubly so if you want to do it from a shell script that is
actually issuing the commands to RDT.

The answer is to add new file in the "info" directory that gives
the status of the last "command" to RDT (either a mkdir, or a
write to one of the control files).

I used the seq_buf* framework because I initially thought a single
command might result in multiple messages. But currently that isn't
true and we could potentially just use "strcpy()/sprintf()" to a
fixed buffer.  I didn't switch to that because the seq_buf* seems
very lightweight and allows for future extra messages while including
checking for exceeding the length of the buffer.

Tony Luck (5):
  x86/intel_rdt: Add framework for better RDT UI diagnostics
  x86/intel_rdt: Add diagnostics when writing the schemata file
  x86/intel_rdt: Add diagnostics when writing the tasks file
  x86/intel_rdt: Add diagnostics when writing the cpus file
  x86/intel_rdt: Add diagnostics when making directories

 arch/x86/kernel/cpu/intel_rdt.h             |  6 ++
 arch/x86/kernel/cpu/intel_rdt_ctrlmondata.c | 61 +++++++++++++++----
 arch/x86/kernel/cpu/intel_rdt_rdtgroup.c    | 93 +++++++++++++++++++++++++----
 3 files changed, 137 insertions(+), 23 deletions(-)

-- 
2.11.0