Fix two bugs that could result in PMC sampling effectively stopping.
In both cases, the the effect of the bug was that a very small positive
number was written to the counter. This means that a large

Fix two bugs that could result in PMC sampling effectively stopping.
In both cases, the the effect of the bug was that a very small positive
number was written to the counter. This means that a large number of
events needed to occur before the next sampling interrupt would trigger.
Even with very frequently occurring events like clock cycles wrapping all
the way around could take a long time. Both bugs occurred when updating
the saved reload count for an outgoing thread on a context switch.

First, the counter-independent code compares the current reload count
against the count set when the thread switched in and generates a delta
to apply to the saved count. If this delta causes the reload counter
to go negative, it would add a full reload interval to wrap it around to
a positive value. The fix is to add the full reload interval if the
resulting counter is zero.

Second, occasionally the raw counter value read during a context switch
has actually wrapped, but an interrupt has not yet triggered. In this
case the existing logic would return a very large reload count (e.g.
2^48 - 2 if the counter had overflowed by a count of 2). This was seen
both for fixed-function and programmable counters on an E5-2643.
Workaround this case by returning a reload count of zero.

PR: 198149
Differential Revision: https://reviews.freebsd.org/D2557
Reviewed by: emaste
MFC after: 1 week
Sponsored by: Norse Corp, Inc.

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Use fixed enum values for PMC_CLASSES().

This removes one of the frequent causes of ABI breakage when new CPU
types are added to hwpmc(4).

Differential Revision: https://reviews.freebsd.org/D2586
R

Use fixed enum values for PMC_CLASSES().

This removes one of the frequent causes of ABI breakage when new CPU
types are added to hwpmc(4).

Differential Revision: https://reviews.freebsd.org/D2586
Reviewed by: davide, emaste, gnn (earlier version)
MFC after: 2 weeks

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Convert hwpmc(4) debug printfs over to KTR.

Differential Revision: https://reviews.freebsd.org/D2487
Reviewed by: davide, emaste
MFC after: 2 weeks
Sponsored by: Norse Corp, Inc.

Move hwpmc(4) debugging code under a new HWPMC_DEBUG option instead of
the broader DEBUG option.

Reviewed by: emaste
MFC after: 2 weeks
Sponsored by: Norse Corp, Inc.

MFhead @ r277403

Reintegrate head: r274132-r277384

Sponsored by: The FreeBSD Foundation

Update the hwpmc driver to have the new type HASWELL_XEON. Also
go back through HASWELL, IVY_BRIDGE, IVY_BRIDGE_XEON and SANDY_BRIDGE
to straighten out all the missing PMCs. We also add a new pmc too

Update the hwpmc driver to have the new type HASWELL_XEON. Also
go back through HASWELL, IVY_BRIDGE, IVY_BRIDGE_XEON and SANDY_BRIDGE
to straighten out all the missing PMCs. We also add a new pmc tool
pmcstudy, this allows one to run the various formulas from
the documents "Using Intel Vtune Amplifier XE on XXX Generation platforms" for
IB/SB and Haswell. The tool also allows one to postulate your own
formulas with any of the various PMC's. At some point I will enahance
this to work with Brendan Gregg's flame-graphs so we can flamegraph
various PMC interactions. Note the manual page also needs some
work (lots of work) but gnn has committed to help me with that ;-)
Reviewed by: gnn
MFC after:1 month
Sponsored by: Netflix Inc.

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Reintegrate head revisions r273096-r277147

Sponsored by: The FreeBSD Foundation

Sync to HEAD@r274766

Clamp too-large hwpmc callchaindepth to the maximum

If the depth requested by the user is too large, it's better to provide
the maximum than the smaller default.

Sponsored by: The FreeBSD Foundation

Merge from head@274682

Sync to HEAD@r274095.

Fix up module unload for syscall_module_handler consumers.

After r273707 it was registering syscalls as static.

This fixes hwpmc module unload.

Reported by: markj

IFC @r273338

Use pmc_destroy_pmc_descriptor() to actually free the pmc, which is
consistent with pmc_destroy_owner_descriptor(). Also be sure to destroy
PMCs if a process exits or execs without explicitly releasi

Use pmc_destroy_pmc_descriptor() to actually free the pmc, which is
consistent with pmc_destroy_owner_descriptor(). Also be sure to destroy
PMCs if a process exits or execs without explicitly releasing them.

Reviewed by: bz, gnn
MFC after: 2 weeks
Sponsored by: EMC / Isilon Storage Division
Differential Revision: https://reviews.freebsd.org/D958

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IFC @r269962

Submitted by: Anish Gupta (akgupt3@gmail.com)

Merge head from 7/28

Sync to HEAD@r269943.

Pull in r267961 and r267973 again. Fix for issues reported will follow.

Revert r267961, r267973:

These changes prevent sysctl(8) from returning proper output,
such as:

1) no output from sysctl(8)
2) erroneously returning ENOMEM with tools like truss(1)
or uname(1

Revert r267961, r267973:

These changes prevent sysctl(8) from returning proper output,
such as:

1) no output from sysctl(8)
2) erroneously returning ENOMEM with tools like truss(1)
or uname(1)
truss: can not get etype: Cannot allocate memory

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Extend the meaning of the CTLFLAG_TUN flag to automatically check if
there is an environment variable which shall initialize the SYSCTL
during early boot. This works for all SYSCTL types both statica

Extend the meaning of the CTLFLAG_TUN flag to automatically check if
there is an environment variable which shall initialize the SYSCTL
during early boot. This works for all SYSCTL types both statically and
dynamically created ones, except for the SYSCTL NODE type and SYSCTLs
which belong to VNETs. A new flag, CTLFLAG_NOFETCH, has been added to
be used in the case a tunable sysctl has a custom initialisation
function allowing the sysctl to still be marked as a tunable. The
kernel SYSCTL API is mostly the same, with a few exceptions for some
special operations like iterating childrens of a static/extern SYSCTL
node. This operation should probably be made into a factored out
common macro, hence some device drivers use this. The reason for
changing the SYSCTL API was the need for a SYSCTL parent OID pointer
and not only the SYSCTL parent OID list pointer in order to quickly
generate the sysctl path. The motivation behind this patch is to avoid
parameter loading cludges inside the OFED driver subsystem. Instead of
adding special code to the OFED driver subsystem to post-load tunables
into dynamically created sysctls, we generalize this in the kernel.

Other changes:
- Corrected a possibly incorrect sysctl name from "hw.cbb.intr_mask"
to "hw.pcic.intr_mask".
- Removed redundant TUNABLE statements throughout the kernel.
- Some minor code rewrites in connection to removing not needed
TUNABLE statements.
- Added a missing SYSCTL_DECL().
- Wrapped two very long lines.
- Avoid malloc()/free() inside sysctl string handling, in case it is
called to initialize a sysctl from a tunable, hence malloc()/free() is
not ready when sysctls from the sysctl dataset are registered.
- Bumped FreeBSD version to indicate SYSCTL API change.

MFC after: 2 weeks
Sponsored by: Mellanox Technologies

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Merge head r233826 through r256722.

IFC @256277

Approved by: ken (mentor)

Remove local change leftover, this should never have been part of
r255745.

Pointy-hat to: davide
Approved by: re (implicit)

Fix lc_lock/lc_unlock() support for rmlocks held in shared mode. With
current lock classes KPI it was really difficult because there was no
way to pass an rmtracker object to the lock/unlock routines

Fix lc_lock/lc_unlock() support for rmlocks held in shared mode. With
current lock classes KPI it was really difficult because there was no
way to pass an rmtracker object to the lock/unlock routines. In order
to accomplish the task, modify the aforementioned functions so that
they can return (or pass as argument) an uinptr_t, which is in the rm
case used to hold a pointer to struct rm_priotracker for current
thread. As an added bonus, this fixes rm_sleep() in the rm shared
case, which right now can communicate priotracker structure between
lc_unlock()/lc_lock().

Suggested by: jhb
Reviewed by: jhb
Approved by: re (delphij)

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