Currently, we use opcode(Event and Event-Selector) + emask to
look up template in p4_templates.
But cache events (L1-dcache-load-misses, LLC-load-misses, etc)
use the same event(P4_REPLAY_EVENT) to do the counting, ie, they
have the same opcode and emask. So we can not use current lookup
mechanism to find the template for cache events.
This patch introduces a "key", which is the index into
p4_templates. The low 12 bits of CCCR are reserved, so we can
hide the "key" in the low 12 bits of hwc->config.
We extract the key from hwc->config and then quickly find the
template.
Signed-off-by: Lin Ming <ming.m.lin@intel.com>
Reviewed-by: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Peter Zijlstra <peterz@infradead.org>
LKML-Reference: <1268908387.13901.127.camel@minggr.sh.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This should turn on instruction counting on P4s, which was missing in
the first version of the new PMU driver.
It's inaccurate for now, we still need dependant event to tag mops
before we can count them precisely. The result is that the number of
instruction may be lifted up.
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Lin Ming <ming.m.lin@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
LKML-Reference: <1268629102.3355.11.camel@minggr.sh.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
The netburst PMU is way different from the "architectural
perfomance monitoring" specification that current CPUs use.
P4 uses a tuple of ESCR+CCCR+COUNTER MSR registers to handle
perfomance monitoring events.
A few implementational details:
1) We need a separate x86_pmu::hw_config helper in struct
x86_pmu since register bit-fields are quite different from P6,
Core and later cpu series.
2) For the same reason is a x86_pmu::schedule_events helper
introduced.
3) hw_perf_event::config consists of packed ESCR+CCCR values.
It's allowed since in reality both registers only use a half
of their size. Of course before making a real write into a
particular MSR we need to unpack the value and extend it to
a proper size.
4) The tuple of packed ESCR+CCCR in hw_perf_event::config
doesn't describe the memory address of ESCR MSR register
so that we need to keep a mapping between these tuples
used and available ESCR (various P4 events may use same
ESCRs but not simultaneously), for this sake every active
event has a per-cpu map of hw_perf_event::idx <--> ESCR
addresses.
5) Since hw_perf_event::idx is an offset to counter/control register
we need to lift X86_PMC_MAX_GENERIC up, otherwise kernel
strips it down to 8 registers and event armed may never be turned
off (ie the bit in active_mask is set but the loop never reaches
this index to check), thanks to Peter Zijlstra
Restrictions:
- No cascaded counters support (do we ever need them?)
- No dependent events support (so PERF_COUNT_HW_INSTRUCTIONS
doesn't work for now)
- There are events with same counters which can't work simultaneously
(need to use intersected ones due to broken counter 1)
- No PERF_COUNT_HW_CACHE_ events yet
Todo:
- Implement dependent events
- Need proper hashing for event opcodes (no linear search, good for
debugging stage but not in real loads)
- Some events counted during a clock cycle -- need to set threshold
for them and count every clock cycle just to get summary statistics
(ie to behave the same way as other PMUs do)
- Need to swicth to use event_constraints
- To support RAW events we need to encode a global list of P4 events
into p4_templates
- Cache events need to be added
Event support status matrix:
Event status
-----------------------------
cycles works
cache-references works
cache-misses works
branch-misses works
bus-cycles partially (does not work on 64bit cpu with HT enabled)
instruction doesnt work (needs dependent event [mop tagging])
branches doesnt work
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Lin Ming <ming.m.lin@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Robert Richter <robert.richter@amd.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <20100311165439.GB5129@lenovo>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Lin Ming