It is always a good idea. In one case, attempting to allocate N+1 PMCs
from a class with N hardware counters would incorrectly attempt to
allocate from the next class in the list. Without this validation, this
can lead to all kinds of strange behaviour.
Since powerpc_allocate_pmc() is used by both the mpc7xxx and ppc970
classes, add a new global to track which is active (it will never be
both).
Reviewed by: luporl, ray
MFC after: 1 week
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D31387
This change adds support for POWER8 and POWER9 PMCs (bare metal and
pseries).
All PowerISA 2.07B non-random events are supported.
Implementation was based on that of PPC970.
Reviewed by: jhibbits
Sponsored by: Eldorado Research Institute (eldorado.org.br)
Differential Revision: https://reviews.freebsd.org/D26110
And add a _74XX suffix to 74XX SPRs.
This is a preparation for adding support to POWER8/9 PMCs, which have most
SPRs equal to 970 ones.
Reviewed by: jhibbits
Sponsored by: Eldorado Research Institute (eldorado.org.br)
Differential Revision: https://reviews.freebsd.org/D26532
pmc_process_interrupt takes 5 arguments when only 3 are needed.
cpu is always available in curcpu and inuserspace can always be
derived from the passed trapframe.
While facially a reasonable cleanup this change was motivated
by the need to workaround a compiler bug.
core2_intr(cpu, tf) ->
pmc_process_interrupt(cpu, ring, pmc, tf, inuserspace) ->
pmc_add_sample(cpu, ring, pm, tf, inuserspace)
In the process of optimizing the tail call the tf pointer was getting
clobbered:
(kgdb) up
at /storage/mmacy/devel/freebsd/sys/dev/hwpmc/hwpmc_mod.c:4709
4709 pmc_save_kernel_callchain(ps->ps_pc,
(kgdb) up
1205 error = pmc_process_interrupt(cpu, PMC_HR, pm, tf,
resulting in a crash in pmc_save_kernel_callchain.
On non-trivial SMP systems the contention on the pmc_owner mutex leads
to a substantial number of samples captured being from the pmc process
itself. This change a) makes buffers larger to avoid contention on the
global list b) makes the working sample buffer per cpu.
Run pmcstat in the background (default event rate of 64k):
pmcstat -S UNHALTED_CORE_CYCLES -O /dev/null sleep 600 &
Before:
make -j96 buildkernel -s >&/dev/null 3336.68s user 24684.10s system 7442% cpu 6:16.50 total
After:
make -j96 buildkernel -s >&/dev/null 2697.82s user 1347.35s system 6058% cpu 1:06.77 total
For more realistic overhead measurement set the sample rate for ~2khz
on a 2.1Ghz processor:
pmcstat -n 1050000 -S UNHALTED_CORE_CYCLES -O /dev/null sleep 6000 &
Collecting 10 samples of `make -j96 buildkernel` from each:
x before
+ after
real time:
N Min Max Median Avg Stddev
x 10 76.4 127.62 84.845 88.577 15.100031
+ 10 59.71 60.79 60.135 60.179 0.29957192
Difference at 95.0% confidence
-28.398 +/- 10.0344
-32.0602% +/- 7.69825%
(Student's t, pooled s = 10.6794)
system time:
N Min Max Median Avg Stddev
x 10 2277.96 6948.53 2949.47 3341.492 1385.2677
+ 10 1038.7 1081.06 1070.555 1064.017 15.85404
Difference at 95.0% confidence
-2277.47 +/- 920.425
-68.1574% +/- 8.77623%
(Student's t, pooled s = 979.596)
x no pmc
+ pmc running
real time:
HEAD:
N Min Max Median Avg Stddev
x 10 58.38 59.15 58.86 58.847 0.22504567
+ 10 76.4 127.62 84.845 88.577 15.100031
Difference at 95.0% confidence
29.73 +/- 10.0335
50.5208% +/- 17.0525%
(Student's t, pooled s = 10.6785)
patched:
N Min Max Median Avg Stddev
x 10 58.38 59.15 58.86 58.847 0.22504567
+ 10 59.71 60.79 60.135 60.179 0.29957192
Difference at 95.0% confidence
1.332 +/- 0.248939
2.2635% +/- 0.426506%
(Student's t, pooled s = 0.264942)
system time:
HEAD:
N Min Max Median Avg Stddev
x 10 1010.15 1073.31 1025.465 1031.524 18.135705
+ 10 2277.96 6948.53 2949.47 3341.492 1385.2677
Difference at 95.0% confidence
2309.97 +/- 920.443
223.937% +/- 89.3039%
(Student's t, pooled s = 979.616)
patched:
N Min Max Median Avg Stddev
x 10 1010.15 1073.31 1025.465 1031.524 18.135705
+ 10 1038.7 1081.06 1070.555 1064.017 15.85404
Difference at 95.0% confidence
32.493 +/- 16.0042
3.15% +/- 1.5794%
(Student's t, pooled s = 17.0331)
Reviewed by: jeff@
Approved by: sbruno@
Differential Revision: https://reviews.freebsd.org/D15155
Mainly focus on files that use BSD 2-Clause license, however the tool I
was using misidentified many licenses so this was mostly a manual - error
prone - task.
The Software Package Data Exchange (SPDX) group provides a specification
to make it easier for automated tools to detect and summarize well known
opensource licenses. We are gradually adopting the specification, noting
that the tags are considered only advisory and do not, in any way,
superceed or replace the license texts.
This supports e500v1, e500v2, and e500mc. Tested only on e500v2, but the
performance counters are identical across all, with e500mc having some
additional events.
Relnotes: Yes
This also fixes asserts on removal of the module for the mpc74xx.
The PowerPC 970 processors have two different types of events: direct events
and indirect events. Thus far only direct events are supported. I included
some documentation in the driver on how indirect events work, but support is
for the future.
MFC after: 1 month
