MFH

Sponsored by: The FreeBSD Foundation

Merge ^/head r295544 through r295600.

Remove tautological cast.

PR: 207068
Submitted by: joss.upton@yahoo.com
MFC after: 2 weeks

Merge ^/head r295351 through r295543.

MFH

Sponsored by: The FreeBSD Foundation

Rename P_KTHREAD struct proc p_flag to P_KPROC.

I left as is an apparent bug in ntoskrnl_var.h:AT_PASSIVE_LEVEL()
definition.

Suggested by: jhb
Sponsored by: The FreeBSD Foundation

MFH

Sponsored by: The FreeBSD Foundation

Do not call vn_fullpath(9) (through the pmc_getfilename() wrapper)
when its result is immediately ignored, i.e. for kernel processes
forked from the user process. Do not test for non-null before fre

Do not call vn_fullpath(9) (through the pmc_getfilename() wrapper)
when its result is immediately ignored, i.e. for kernel processes
forked from the user process. Do not test for non-null before freeing
string.

Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks

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MFH r289384-r293170

Sponsored by: The FreeBSD Foundation

Catch up with head (r291075).

Improve accuracy of PMC sampling frequency

The code tracks a counter which is the number of events until the next
sample. On context switch in, it loads the saved counter. On context
switch out, it

Improve accuracy of PMC sampling frequency

The code tracks a counter which is the number of events until the next
sample. On context switch in, it loads the saved counter. On context
switch out, it tries to calculate a new saved counter.

Problems:

1. The saved counter was shared by all threads in a process. However, this
means that all threads would be initially loaded with the same saved
counter. However, that could result in sampling more often than once every
X number of events.

2. The calculation to determine a new saved counter was backwards. It
added when it should have subtracted, and subtracted when it should have
added. Assume a single-threaded process with a reload count of 1000 events.
Assuming the counter on context switch in was 100 and the counter on context
switch out was 50 (meaning the thread has "consumed" 50 more events), the
code would calculate a new saved counter of 150 (instead of the proper 50).

Fix:

1. As soon as the saved counter is used to initialize a monitor for a
thread on context switch in, set the saved counter to the reload count.
That way, subsequent threads to use the saved counter will get the full
reload count, assuring we sample at least once every X number of events
(across all threads).

2. Change the calculation of the saved counter. Due to the change to the
saved counter in #1, we simply need to add (modulo the reload count) the
remaining counter time we retrieve from the CPU when a thread is context
switched out.

Differential Revision: https://reviews.freebsd.org/D4122
Approved by: gnn (mentor)
MFC after: 1 month
Sponsored by: Juniper Networks

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Optimizations to the way hwpmc gathers user callchains

Changes to the code to gather user stacks:
* Delay setting pmc_cpumask until we actually have the stack.
* When recording user stack traces, on

Optimizations to the way hwpmc gathers user callchains

Changes to the code to gather user stacks:
* Delay setting pmc_cpumask until we actually have the stack.
* When recording user stack traces, only walk the portion of the ring
that should have samples for us.

Sponsored by: Juniper Networks
Approved by: gnn (mentor)
MFC after: 1 month

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Fix hwpmc "stalled" behavior

Currently, there is a single pm_stalled flag that tracks whether a
performance monitor was "stalled" due to insufficent ring buffer
space for samples. However, because t

Fix hwpmc "stalled" behavior

Currently, there is a single pm_stalled flag that tracks whether a
performance monitor was "stalled" due to insufficent ring buffer
space for samples. However, because the same performance monitor
can run on multiple processes or threads at the same time, a single
pm_stalled flag that impacts them all seems insufficient.

In particular, you can hit corner cases where the code fails to stop
performance monitors during a context switch out, because it thinks
the performance monitor is already stopped. However, in reality,
it may be that only the monitor running on a different CPU was stalled.

This patch attempts to fix that behavior by tracking on a per-CPU basis
whether a PM desires to run and whether it is "stalled". This lets the
code make better decisions about when to stop PMs and when to try to
restart them. Ideally, we should avoid the case where the code fails
to stop a PM during a context switch out.

Sponsored by: Juniper Networks
Reviewed by: jhb
Approved by: gnn (mentor)
Differential Revision: https://reviews.freebsd.org/D4124

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Merge from head

Sponsored by: Gandi.net

Finish merging from head, messed up in previous attempt

Merge r286744-r287584 from head.

Merge ^/head r286858 through r287489.

Merge from HEAD

When forking a child process with PMC_F_DESCENDANTS set in pmc_attach()
in the parent, we will inherit the pmcids but cannot execute any operations
on them in the child. The reason for this is that

When forking a child process with PMC_F_DESCENDANTS set in pmc_attach()
in the parent, we will inherit the pmcids but cannot execute any operations
on them in the child. The reason for this is that pmc_find_pmc() only
tries to find the current process on the owners hash list, but given the
child does not own the attachment, we cannot find it.
Thus, in case the initial lookup fails, try to find the pmc_process state
affiliated with the child process, lookup the pmc from there using the
row index, and get the owner process from that pmc.
Then continue as normal and lookup the pmc context of the owner (process).

This allows us to call, e.g., pmc_start() in the child process before we
start the work there, but to collect the accumulated results later in
the parent.

Sponsored by: DARPA,AFRL
Obtained from: L41
Tested by: rwatson, L41
MFC after: 4 weeks
Reviewed by: gnn
Differential Revision: https://reviews.freebsd.org/D2052

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Catch up with HEAD (r280229-r284686).

Merge from head

Merged ^/head r283871 through r284187.

Provide vnode in memory map info for files on tmpfs

When providing memory map information to userland, populate the vnode pointer
for tmpfs files. Set the memory mapping to appear as a vnode type,

Provide vnode in memory map info for files on tmpfs

When providing memory map information to userland, populate the vnode pointer
for tmpfs files. Set the memory mapping to appear as a vnode type, to match
FreeBSD 9 behavior.

This fixes the use of tmpfs files with the dtrace pid provider,
procstat -v, procfs, linprocfs, pmc (pmcstat), and ptrace (PT_VM_ENTRY).

Submitted by: Eric Badger <eric@badgerio.us> (initial revision)
Obtained from: Dell Inc.
PR: 198431
MFC after: 2 weeks
Reviewed by: jhb
Approved by: kib (mentor)

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MFH: r282615-r283655

Sponsored by: The FreeBSD Foundation

Merge sync of head