When two (or more) contexts output to the same buffer, it is possible
to observe half written output.
Suppose we have CPU0 doing perf_counter_mmap(), CPU1 doing
perf_counter_overflow(). If CPU1 does a wakeup and exposes head to
user-space, then CPU2 can observe the data CPU0 is still writing.
[ Impact: fix occasionally corrupted profiling records ]
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
LKML-Reference: <20090501102533.007821627@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
The type of counter index is sometimes implemented as unsigned
int. This patch changes this to have a consistent usage of int.
[ Impact: cleanup ]
Signed-off-by: Robert Richter <robert.richter@amd.com>
Cc: Paul Mackerras <paulus@samba.org>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1241002046-8832-21-git-send-email-robert.richter@amd.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This patch renames struct hw_perf_counter_ops into struct pmu. It
introduces a structure to describe a cpu specific pmu (performance
monitoring unit). It may contain ops and data. The new name of the
structure fits better, is shorter, and thus better to handle. Where it
was appropriate, names of function and variable have been changed too.
[ Impact: cleanup ]
Signed-off-by: Robert Richter <robert.richter@amd.com>
Cc: Paul Mackerras <paulus@samba.org>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1241002046-8832-7-git-send-email-robert.richter@amd.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This is only needed for CONFIG_PERF_COUNTERS enabled.
[ Impact: cleanup ]
Signed-off-by: Robert Richter <robert.richter@amd.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
LKML-Reference: <1241002046-8832-3-git-send-email-robert.richter@amd.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: add sysctl for paranoid/relaxed perfcounters policy
Allow the use of system wide perf counters to everybody, but provide
a sysctl to disable it for the paranoid security minded.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
LKML-Reference: <20090409085524.514046352@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Paul suggested we allow for data addresses to be recorded along with
the traditional IPs as power can provide these.
For now, only the software pagefault events provide data addresses,
but in the future power might as well for some events.
x86 doesn't seem capable of providing this atm.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
LKML-Reference: <20090408130409.394816925@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Move PERF_RECORD_TIME so that all the fixed length items come before
the variable length ones.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
LKML-Reference: <20090408130409.307926436@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Similar to the mmap data stream, add one that tracks the task COMM field,
so that the userspace reporting knows what to call a task.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
LKML-Reference: <20090408130409.127422406@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Add a few comments because I was forgetting what field what for what
functionality.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
LKML-Reference: <20090408130409.036984214@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Push the PERF_EVENT_COUNTER_OVERFLOW bit into the misc field so that
we can have the full 32bit for PERF_RECORD_ bits.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
LKML-Reference: <20090408130408.891867663@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Limit the size of each record to 64k (or should we count in multiples
of u64 and have a 512K limit?), this gives 16 bits or spare room in the
header, which we can use for misc bits, so as to not have to grow the
record with u64 every time we have a few bits to report.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
LKML-Reference: <20090408130408.769271806@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Since perf_counter_context is switched along with tasks, we can
maintain the context time without using the task runtime clock.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
LKML-Reference: <20090406094518.353552838@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Currently the definition of an event is slightly ambiguous. We have
wakeup events, for poll() and SIGIO, which are either generated
when a record crosses a page boundary (hw_events.wakeup_events == 0),
or every wakeup_events new records.
Now a record can be either a counter overflow record, or a number of
different things, like the mmap PROT_EXEC region notifications.
Then there is the PERF_COUNTER_IOC_REFRESH event limit, which only
considers counter overflows.
This patch changes then wakeup_events and SIGIO notification to only
consider overflow events. Furthermore it changes the SIGIO notification
to report SIGHUP when the event limit is reached and the counter will
be disabled.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
LKML-Reference: <20090406094518.266679874@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Provide means to auto-disable the counter after 'n' overflow events.
Create the counter with hw_event.disabled = 1, and then issue an
ioctl(fd, PREF_COUNTER_IOC_REFRESH, n); to set the limit and enable
the counter.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
LKML-Reference: <20090406094518.083139737@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
By popular request, provide means to log a timestamp along with the
counter overflow event.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
LKML-Reference: <20090406094518.024173282@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Prepare for more generic overflow handling. The new perf_counter_overflow()
method will handle the generic bits of the counter overflow, and can return
a !0 return value, in which case the counter should be (soft) disabled, so
that it won't count until it's properly disabled.
XXX: do powerpc and swcounter
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
LKML-Reference: <20090406094517.812109629@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Prepare the pending infrastructure to do more than wakeups.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
LKML-Reference: <20090406094517.634732847@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Provide support for fcntl() I/O availability signals.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
LKML-Reference: <20090406094517.579788800@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Change the callchain context entries to u16, so as to gain some space.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
LKML-Reference: <20090406094517.457320003@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Update the userspace read method.
Paul noted that:
- userspace cannot observe ->lock & 1 on the same cpu.
- we need a barrier() between reading ->lock and ->index
to ensure we read them in that prticular order.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
LKML-Reference: <20090406094517.368446033@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Paul noted that we don't need SMP barriers for the mmap() counter read
because its always on the same cpu (otherwise you can't access the hw
counter anyway).
So remove the SMP barriers and replace them with regular compiler
barriers.
Further, update the comment to include a race free method of reading
said hardware counter. The primary change is putting the pmc_read
inside the seq-loop, otherwise we can still race and read rubbish.
Noticed-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Orig-LKML-Reference: <20090402091319.577951445@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Put in counts to tell which ips belong to what context.
-----
| | hv
| --
nr | | kernel
| --
| | user
-----
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Orig-LKML-Reference: <20090402091319.493101305@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
By request, provide a way to request a wakeup every 'n' events instead
of every page of output.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Orig-LKML-Reference: <20090402091319.323309784@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Per suggestion from Paul, move the event overflow bits to record_type
and sanitize the enums a bit.
Breaks the ABI -- again ;-)
Suggested-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Orig-LKML-Reference: <20090402091319.151921176@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Provide the generic callchain support bits. If hw_event->callchain is
set the arch specific perf_callchain() function is called upon to
provide a perf_callchain_entry structure filled with the current
callchain.
If it does so, it is added to the overflow output event.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Paul Mackerras <paulus@samba.org>
Orig-LKML-Reference: <20090330171024.254266860@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Breaks ABI yet again :-)
Change the event type so that [0, 2^31-1] are regular event types, but
[2^31, 2^32-1] forms a bitmask for overflow events.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Paul Mackerras <paulus@samba.org>
Orig-LKML-Reference: <20090330171024.047961770@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Currently the profiling information returns userspace IPs but no way
to correlate them to userspace code. Userspace could look into
/proc/$pid/maps but that might not be current or even present anymore
at the time of analyzing the IPs.
Therefore provide means to track the mmap information and provide it
in the output stream.
XXX: only covers mmap()/munmap(), mremap() and mprotect() are missing.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Paul Mackerras <paulus@samba.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Orig-LKML-Reference: <20090330171023.417259499@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
It just occured to me it is possible to have multiple contending
updates of the userpage (mmap information vs overflow vs counter).
This would break the seqlock logic.
It appear the arch code uses this from NMI context, so we cannot
possibly serialize its use, therefore separate the data_head update
from it and let it return to its original use.
The arch code needs to make sure there are no contending callers by
disabling the counter before using it -- powerpc appears to do this
nicely.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Paul Mackerras <paulus@samba.org>
Orig-LKML-Reference: <20090330171023.241410660@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
While going over the wakeup code I noticed delayed wakeups only work
for hardware counters but basically all software counters rely on
them.
This patch unifies and generalizes the delayed wakeup to fix this
issue.
Since we're dealing with NMI context bits here, use a cmpxchg() based
single link list implementation to track counters that have pending
wakeups.
[ This should really be generic code for delayed wakeups, but since we
cannot use cmpxchg()/xchg() in generic code, I've let it live in the
perf_counter code. -- Eric Dumazet could use it to aggregate the
network wakeups. ]
Furthermore, the x86 method of using TIF flags was flawed in that its
quite possible to end up setting the bit on the idle task, loosing the
wakeup.
The powerpc method uses per-cpu storage and does appear to be
sufficient.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Paul Mackerras <paulus@samba.org>
Orig-LKML-Reference: <20090330171023.153932974@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: new functionality
Currently, if there are more counters enabled than can fit on the CPU,
the kernel will multiplex the counters on to the hardware using
round-robin scheduling. That isn't too bad for sampling counters, but
for counting counters it means that the value read from a counter
represents some unknown fraction of the true count of events that
occurred while the counter was enabled.
This remedies the situation by keeping track of how long each counter
is enabled for, and how long it is actually on the cpu and counting
events. These times are recorded in nanoseconds using the task clock
for per-task counters and the cpu clock for per-cpu counters.
These values can be supplied to userspace on a read from the counter.
Userspace requests that they be supplied after the counter value by
setting the PERF_FORMAT_TOTAL_TIME_ENABLED and/or
PERF_FORMAT_TOTAL_TIME_RUNNING bits in the hw_event.read_format field
when creating the counter. (There is no way to change the read format
after the counter is created, though it would be possible to add some
way to do that.)
Using this information it is possible for userspace to scale the count
it reads from the counter to get an estimate of the true count:
true_count_estimate = count * total_time_enabled / total_time_running
This also lets userspace detect the situation where the counter never
got to go on the cpu: total_time_running == 0.
This functionality has been requested by the PAPI developers, and will
be generally needed for interpreting the count values from counting
counters correctly.
In the implementation, this keeps 5 time values (in nanoseconds) for
each counter: total_time_enabled and total_time_running are used when
the counter is in state OFF or ERROR and for reporting back to
userspace. When the counter is in state INACTIVE or ACTIVE, it is the
tstamp_enabled, tstamp_running and tstamp_stopped values that are
relevant, and total_time_enabled and total_time_running are determined
from them. (tstamp_stopped is only used in INACTIVE state.) The
reason for doing it like this is that it means that only counters
being enabled or disabled at sched-in and sched-out time need to be
updated. There are no new loops that iterate over all counters to
update total_time_enabled or total_time_running.
This also keeps separate child_total_time_running and
child_total_time_enabled fields that get added in when reporting the
totals to userspace. They are separate fields so that they can be
atomic. We don't want to use atomics for total_time_running,
total_time_enabled etc., because then we would have to use atomic
sequences to update them, which are slower than regular arithmetic and
memory accesses.
It is possible to measure total_time_running by adding a task_clock
counter to each group of counters, and total_time_enabled can be
measured approximately with a top-level task_clock counter (though
inaccuracies will creep in if you need to disable and enable groups
since it is not possible in general to disable/enable the top-level
task_clock counter simultaneously with another group). However, that
adds extra overhead - I measured around 15% increase in the context
switch latency reported by lat_ctx (from lmbench) when a task_clock
counter was added to each of 2 groups, and around 25% increase when a
task_clock counter was added to each of 4 groups. (In both cases a
top-level task-clock counter was also added.)
In contrast, the code added in this commit gives better information
with no overhead that I could measure (in fact in some cases I
measured lower times with this code, but the differences were all less
than one standard deviation).
[ v2: address review comments by Andrew Morton. ]
Signed-off-by: Paul Mackerras <paulus@samba.org>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Andrew Morton <akpm@linux-foundation.org>
Orig-LKML-Reference: <18890.6578.728637.139402@cargo.ozlabs.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Allow cpu wide counters to profile userspace by providing what process
the sample belongs to.
This raises the first issue with the output type, lots of these
options: group, tid, callchain, etc.. are non-exclusive and could be
combined, suggesting a bitfield.
However, things like the mmap() data stream doesn't fit in that.
How to split the type field...
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Arjan van de Ven <arjan@infradead.org>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Orig-LKML-Reference: <20090325113317.013775235@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Provide a {type,size} header for each output entry.
This should provide extensible output, and the ability to mix multiple streams.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Arjan van de Ven <arjan@infradead.org>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Orig-LKML-Reference: <20090325113316.831607932@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: fix kerneltop 100% CPU usage
Only return a poll event when there's actually been one, poll_wait()
doesn't actually wait for the waitq you pass it, it only enqueues
you on it.
Only once all FDs have been iterated and none of thm returned a
poll-event will it schedule().
Also make it return POLL_HUP when there's not mmap() area to read from.
Further, fix a silly bug in the write code.
Reported-by: Mike Galbraith <efault@gmx.de>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arjan van de Ven <arjan@infradead.org>
Orig-LKML-Reference: <1237897096.24918.181.camel@twins>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: Rework the perfcounter output ABI
use sys_read() only for instant data and provide mmap() output for all
async overflow data.
The first mmap() determines the size of the output buffer. The mmap()
size must be a PAGE_SIZE multiple of 1+pages, where pages must be a
power of 2 or 0. Further mmap()s of the same fd must have the same
size. Once all maps are gone, you can again mmap() with a new size.
In case of 0 extra pages there is no data output and the first page
only contains meta data.
When there are data pages, a poll() event will be generated for each
full page of data. Furthermore, the output is circular. This means
that although 1 page is a valid configuration, its useless, since
we'll start overwriting it the instant we report a full page.
Future work will focus on the output format (currently maintained)
where we'll likey want each entry denoted by a header which includes a
type and length.
Further future work will allow to splice() the fd, also containing the
async overflow data -- splice() would be mutually exclusive with
mmap() of the data.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Orig-LKML-Reference: <20090323172417.470536358@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: new feature giving performance improvement
This adds the ability for userspace to do an mmap on a hardware counter
fd and get access to a read-only page that contains the information
needed to translate a hardware counter value to the full 64-bit
counter value that would be returned by a read on the fd. This is
useful on architectures that allow user programs to read the hardware
counters, such as PowerPC.
The mmap will only succeed if the counter is a hardware counter
monitoring the current process.
On my quad 2.5GHz PowerPC 970MP machine, userspace can read a counter
and translate it to the full 64-bit value in about 30ns using the
mmapped page, compared to about 830ns for the read syscall on the
counter, so this does give a significant performance improvement.
Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Orig-LKML-Reference: <20090323172417.297057964@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Tracepoint events like lock_acquire and software counters like
pagefaults can recurse into the perf counter code again, avoid that.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Orig-LKML-Reference: <20090323172417.152096433@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Since the bitfields turned into a bit of a mess, remove them and rely on
good old masks.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Orig-LKML-Reference: <20090323172417.059499915@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: build fix for powerpc
Commit db3a944aca35ae61 ("perf_counter: revamp syscall input ABI")
expanded the hw_event.type field into a union of structs containing
bitfields. In particular it introduced a type field and a raw_type
field, with the intention that the 1-bit raw_type field should
overlay the most-significant bit of the 8-bit type field, and in fact
perf_counter_alloc() now assumes that (or at least, assumes that
raw_type doesn't overlay any of the bits that are 1 in the values of
PERF_TYPE_{HARDWARE,SOFTWARE,TRACEPOINT}).
Unfortunately this is not true on big-endian systems such as PowerPC,
where bitfields are laid out from left to right, i.e. from most
significant bit to least significant. This means that setting
hw_event.type = PERF_TYPE_SOFTWARE will set hw_event.raw_type to 1.
This fixes it by making the layout depend on whether or not
__BIG_ENDIAN_BITFIELD is defined. It's a bit ugly, but that's what
we get for using bitfields in a user/kernel ABI.
Also, that commit didn't fix up some places in arch/powerpc/kernel/
perf_counter.c where hw_event.raw and hw_event.event_id were used.
This fixes them too.
Signed-off-by: Paul Mackerras <paulus@samba.org>
Impact: cleanup
Having 3 slightly different copies of the same code around does nobody
any good. First step in revamping the output format.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Orig-LKML-Reference: <20090319194233.929962222@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: modify ABI
The hardware/software classification in hw_event->type became a little
strained due to the addition of tracepoint tracing.
Instead split up the field and provide a type field to explicitly specify
the counter type, while using the event_id field to specify which event to
use.
Raw counters still work as before, only the raw config now goes into
raw_event.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Orig-LKML-Reference: <20090319194233.836807573@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: new perfcounters feature
Enable usage of tracepoints as perf counter events.
tracepoint event ids can be found in /debug/tracing/event/*/*/id
and (for now) are represented as -65536+id in the type field.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Orig-LKML-Reference: <20090319194233.744044174@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
I noticed that the counter_list only includes top-level counters, thus
perf_swcounter_event() will miss sw-counters in groups.
Since perf_swcounter_event() also wants an RCU safe list, create a new
event_list that includes all counters and uses RCU list ops and use call_rcu
to free the counter structure.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Use hrtimers to profile timer based sampling for the software time
counters.
This allows platforms without hardware counter support to still
perform sample based profiling.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Provide separate sw counters for major and minor page faults.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Provide generic software counter infrastructure that supports
software events.
This will be used to allow sample based profiling based on software
events such as pagefaults. The current infrastructure can only
provide a count of such events, no place information.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
The sum of bits is 65 currently not 64 - so reduce the # of reserved bits
from 55 to 54.
Cc: Paul Mackerras <paulus@samba.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: ABI change
This expands several fields in the perf_counter_hw_event struct and adds
a "flags" argument to the perf_counter_open system call, in order that
features can be added in future without ABI changes.
In particular the record_type field is expanded to 64 bits, and the
space for flag bits has been expanded from 32 to 64 bits.
This also adds some new fields:
* read_format (64 bits) is intended to provide a way to specify what
userspace wants to get back when it does a read() on a simple
(non-interrupting) counter;
* exclude_idle (1 bit) provides a way for userspace to ask that events
that occur when the cpu is idle be excluded;
* extra_config_len will provide a way for userspace to supply an
arbitrary amount of extra machine-specific PMU configuration data
immediately following the perf_counter_hw_event struct, to allow
sophisticated users to program things such as instruction matching
CAMs and address range registers;
* __reserved_3 and __reserved_4 provide space for future expansion.
Signed-off-by: Paul Mackerras <paulus@samba.org>
This fixes three issues noticed by Arnd Bergmann:
- Add #ifdef __KERNEL__ and move some things around in perf_counter.h
to make sure only the bits that userspace needs are exported to
userspace.
- Use __u64, __s64, __u32 types in the structs exported to userspace
rather than u64, s64, u32.
- Make the sys_perf_counter_open syscall available to the SPUs on
Cell platforms.
And one issue that I noticed in looking at the code again:
- Wrap the perf_counter_open syscall with SYSCALL_DEFINE4 so we get
the proper handling of int arguments on ppc64 (and some other 64-bit
architectures).
Reported-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Paul Mackerras <paulus@samba.org>
Jaswinder Singh Rajput reported that commit 23a185ca8a caused the
context switch and migration software counters to report zero always.
With that commit, the software counters only count events that occur
between sched-in and sched-out for a task. This is necessary for the
counter enable/disable prctls and ioctls to work. However, the
context switch and migration counts are incremented after sched-out
for one task and before sched-in for the next. Since the increment
doesn't occur while a task is scheduled in (as far as the software
counters are concerned) it doesn't count towards any counter.
Thus the context switch and migration counters need to count events
that occur at any time, provided the counter is enabled, not just
those that occur while the task is scheduled in (from the perf_counter
subsystem's point of view). The problem though is that the software
counter code can't tell the difference between being enabled and being
scheduled in, and between being disabled and being scheduled out,
since we use the one pair of enable/disable entry points for both.
That is, the high-level disable operation simply arranges for the
counter to not be scheduled in any more, and the high-level enable
operation arranges for it to be scheduled in again.
One way to solve this would be to have sched_in/out operations in the
hw_perf_counter_ops struct as well as enable/disable. However, this
takes a simpler approach: it adds a 'prev_state' field to the
perf_counter struct that allows a counter's enable method to know
whether the counter was previously disabled or just inactive
(scheduled out), and therefore whether the enable method is being
called as a result of a high-level enable or a schedule-in operation.
This then allows the context switch, migration and page fault counters
to reset their hw.prev_count value in their enable functions only if
they are called as a result of a high-level enable operation.
Although page faults would normally only occur while the counter is
scheduled in, this changes the page fault counter code too in case
there are ever circumstances where page faults get counted against a
task while its counters are not scheduled in.
Reported-by: Jaswinder Singh Rajput <jaswinder@kernel.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
