Hi Harald,
You are right, the perf mem tool dosn't support stting the latency
threshold. It should be a very easy first contribution to kernel for
myself ;-)
Regarding the timestamp, I nver need such information, but as you said
you can't tll to the hardware (on Intel I mean) to record it along with
processor state information. I don't know how th kernel part of perf
configure PEBS, but why would the kernel pay the overhead of an
interrupt by using 1 slot buffers ? Only for recording timestamp ?
----
Manu
On 02/04/2015 03:20 PM, Harald Servat wrote:
Hello Manuel,
I'm running Linux 3.11 but I don't see a way to setup the latency
threshold there. My option flags include:
-t, --type=
-D, --dump-raw-samples=
-x, --field-separator
-C, --cpu-list
so I guess that this option is not implemented in perf (at least on
3.11). So I need to capture all the samples and then discard those that
surpass that threshold.
Going back into your example, is it possible to capture / show the
timestamp for the captured samples? I've seen the Intel documentation,
and there aren't timestamps in PEBS entries so that may require
additional work. IIRC, someone of the list told me that perf allocates a
1-entry PEBS buffer so every time PEBS fills it, perf somehow gets an
interrupt indicating that it has to flush it. This way, perf can
attribute a timestamp to that sample also.
Thank you very much!
On 04/02/15 15:00, Manuel Selva wrote:
Hi Harald,
Yes you can with the "perf mem" tool. It has been introduced in kernel
3.10 (correct me if I am wrong, not very sure about that). It's built on
top of perf mem record and perf mem report but hide for you the
complxity of choosing the memory events . See "man perf mem" for th
details.
----------
Manuel
2015-02-04 13:48 GMT+01:00 Harald Servat <[email protected]
<mailto:[email protected]>>:
Hello list,
is there any way to configure perf to sample memory references
through PEBS and enable the Load Latency Performance Monitoring
Facility (section 18.7.1.2 from the Intel 64 and IA-32 Architectures
Software Developer's Manual).
Thank you very much in advance.
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