Re: [PATCH 0/5] (Revision 5) IBS Userspace Support

[Maynard J. <may...@us...>]

Suravee,
I applied your IBS support patches.  Congratulations!  :-)

I integrated ChangeLog entries to each of your 4 code patches, so ended up committing 4 patches (instead of 5, since your first patch was just a standalone ChangeLog patch).  Please do a fresh checkout from CVS and verify it all works.

Thanks.
-Maynard


++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Suravee Suthikulpanit wrote:
> Change Notes:
> ============
> 
> Changes from revision 4:
>     - Made modifications based on feedback from Maynard.
> 	* Run check_style.py script
> 	* Fixed coding style to follow the guideline
> 	* Remove trans_IBS_OP_log_dcmissinfo
> 	* Rework some logics in opannotate
> 	* Remove libpp changes
>     - Tested with kernel-2.8.29.1 (rebuild the kernel after enabling IBS)
>     - "make distcheck" passed
> 
> Changes from revision 3:
>     - Tested with kernel-2.8.29.1 (rebuild the kernel after enabling IBS)
>     - "make distcheck" passed
>     - Modified to use OProfile Extended-feature Interface
>     - Fixed opannotate bug
>     - Add IBS data filtering
> 
> 
> Introduction
> ============
> 
> These patches extend Oprofile to support Instruction
> Based Sampling (IBS) available on AMD Family 10h processors.
> The specification of IBS is described in section 2.17.2 of "BIOS and
> Kernel Developer's Guide (BKDG) For AMD Family 10h Processors".
> 
> IBS provides wide range of precise information on instruction fetch
> phase and execution phase. The document "Instruction-Based Sampling:
> A New Performance Analysis Technique for AMD Family 10h Processors"
> explains and demonstrates the uses of IBS in details.
> 
> The patches are made against the head of CVS. The required kernel
> support is in the kernel patch starting from patch-2.6.28-rc2.
> 
> 
> Design Outline
> ==============
> 
> = Terms =
> 
> EBS: Event based sampling
> IBS: Instructions based sampling
> 
> 
> = opcontrol changes =
> 
> Enabling IBS profiling is done simply by specifying IBS events through
> the "--event=" options similar to the event-based profiling:
> 
>     * opcontrol --event=IBS_FETCH_XXXX:<count>:<um>:<kernel>:<user>
>     * opcontrol --event=IBS_OP_XXXX:<count>:<um>:<kernel>:<user>
> 
> IBS performance events are listed in the event/unitmask files.  opcontrol
> has been modified to handle these events, configure the driver interface 
> (/dev/oprofile/ibs_fetch/... and /dev/oprofile/ibs_op/...) and start oprofiled 
> with the appropriate options based on the users input.
> 
> 
> = Driver interface changes =
> 
> Two directories, /dev/oprofile/ibs_fetch and /dev/oprofile/ibs_op are 
> added to the oprofilefs allowing the control of MSRs through oprofile.ko 
> module.
> 
> Both directories contains device file enable and max_count.
> The file "enable" enables and disables the functionalities of the
> directory containing it. The "max_count" file specifies the
> maximum count value of the periodic op/fetch counter (bit 15:0
> of MSR 0xC001_1030 and 0xC001_1033).
> 
> Directory "ibs_fetch" contains "ran_enable" file in addition to the
> files mentioned. It corresponds to bit 57 of MSR 0xC001_1030. When
> enabled, bits 3:0 of the fetch counter are randomized when IBS fetch
> is set to start the fetch counter.
> 
> Directory "ibs_op" contains "dispatched_op" file in addition to the
> files mentioned. It corresponds to bit 19 of MSR 0xC001_1033.
> This bit selects the mode of instruction tagging for IBS-Op, (0: Count Clock
> Cycle, 1:Count dispatched ops)
> 
> 
> = Daemon changes =
> 
> To differentiate IBS events from EBS events and to accommodate the fact
> that IBS events are not uniform in length when read from buffer. Two
> escape codes "IBS_FETCH_SAMPLE" and "IBS_OP_SAMPLE" and their handlers
> are added.
> 
> Each IBS sample contains encapsulates multitudes of data. For example,
> single IBS fetch data contains information of instruction cache L2TLB
> miss, instruction cache L1TLB miss, L1 TLB page size, instruction cache
> miss, linear address, physical address, etc. Howver, only the performance 
> data specified by users (through opcontrol) are logged.
> 
> OProfile Extended-feature Interface is used to hook up IBS handler, which
> translates and logs IBS samples.
> 
> 
> = Reporting tool changes =
> 
> Virtual address associated with IBS fetch may lie in the middle of an
> instruction. opannotate are modified to handle this case when printing out report.
> 
> 
> References
> ================
> 
> "BIOS and Kernel Developer's Guide (BKDG) For AMD Family 10h Processors"
> (http://www.amd.com/us-en/assets/content_type/white_papers_and_tech_docs/31116.pdf)
> 
> Drongowski, Paul. "Instruction-Based Sampling: A New Performance
> Analysis Technique for AMD Family 10h Processors". 2007.
> (http://developer.amd.com/assets/AMD_IBS_paper_EN.pdf)
> 
> 
> 
> 
> 
> 
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