Merge ^/head r295351 through r295543.

MFH

Sponsored by: The FreeBSD Foundation

Minor grammar fix in comment.

MfH @r295202

Expect to see panics in routing code at least now.

MFH

Sponsored by: The FreeBSD Foundation

Merge ^/head r294777 through r294960.

The bread() function was inconsistent about whether it would return
a buffer pointer in the event of an error (for some errors it would
return a buffer pointer and for other errors it would not retur

The bread() function was inconsistent about whether it would return
a buffer pointer in the event of an error (for some errors it would
return a buffer pointer and for other errors it would not return a
buffer pointer). The cluster_read() function was similarly inconsistent.

Clients of these functions were inconsistent in handling errors.
Some would assume that no buffer was returned after an error and
would thus lose buffers under certain error conditions. Others would
assume that brelse() should always be called after an error and
would thus panic the system under certain error conditions.

To correct both of these problems with minimal code churn, bread()
and cluster_write() now always free the buffer when returning an
error thus ensuring that buffers will never be lost. The brelse()
routine checks for being passed a NULL buffer pointer and silently
returns to avoid panics. Thus both approaches to handling error
returns from bread() and cluster_read() will work correctly.

Future code should be written assuming that bread() and cluster_read()
will never return a buffer with an error, so should not attempt to
brelse() the buffer when an error is returned.

Reviewed by: kib

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MFH r289384-r293170

Sponsored by: The FreeBSD Foundation

MFH @r292599

This includes the pluggable TCP framework and other chnages to the
netstack to track for VNET stability.

Security: The FreeBSD Foundation

Don't call wakeup if we're just returning reserved space; just
return the reservation and wait for more space to appear.

Submitted by: jeff
Reviewed by: kib

Don't use 0 for pointer comparison

Use NULL instead of 0 for comparison with panicstr.

MFC after: 1 week
Sponsored by: Multiplay

Catch up with head (r291075).

Merge from head r290483

Add a sched_yield() to work around low memory conditions in the current code.

Things seem to get stuck in low memory conditions where no bufs are available,
the reclamation path is called to wakeup

Add a sched_yield() to work around low memory conditions in the current code.

Things seem to get stuck in low memory conditions where no bufs are available,
the reclamation path is called to wakeup the daemon, but no sleeping is done.
Because of this, we are stuck in a tight loop in the current process and
never run said reclamation path.

This was introduced in r289279 . This is only a temporary workaround
to restore system usefulness until the more permanent solutions can be
found.

Tested:

* Carambola2, 64MB (and 32MB by manual config.)

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Merge from head

The error classification from lower layers is a poor indicator of
whether an error is recoverable. Always re-dirty the buffer on errors
from write requests. The invalidation we used to do for errors

The error classification from lower layers is a poor indicator of
whether an error is recoverable. Always re-dirty the buffer on errors
from write requests. The invalidation we used to do for errors not EIO
doesn't need to be done for a device that's really gone, since that's
done in a different path.

Reviewed by: mckusick@, kib@

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getnewbuf: Initialize bp to avoid uninitialized pointer dereference and brelse().

This came in recently in r289279.

Coverity CID: 1331561

Merge from head

Sponsored by: Gandi.net

Merge from head

MFH to r289370

Sponsored by: The FreeBSD Foundation

Parallelize the buffer cache and rewrite getnewbuf(). This results in a
8x performance improvement in a micro benchmark on a 4 socket machine.

- Get buffer headers from a per-cpu uma cache that si

Parallelize the buffer cache and rewrite getnewbuf(). This results in a
8x performance improvement in a micro benchmark on a 4 socket machine.

- Get buffer headers from a per-cpu uma cache that sits in from of the
free queue.
- Use a per-cpu quantum cache in vmem to eliminate contention for kva.
- Use multiple clean queues according to buffer cache size to eliminate
clean queue lock contention.
- Introduce a bufspace daemon that attempts to prevent getnewbuf() callers
from blocking or doing direct recycling.
- Close some bufspace allocation races that could lead to endless
recycling.
- Further the transition to a more modern style of small functions grouped
by prefix in order to improve growing complexity.

Sponsored by: EMC / Isilon
Reviewed by: kib
Tested by: pho

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Merge from head

Sync up with head up to r289211.

Merge from head

Merge ^/head r288457 through r288830.