It is typical to have one, but no longer true for multi-actuator HDDs
with separate LUN for each actuator.
MFC after: 4 days
Sponsored by: iXsystems, Inc.
ioctl(2) handling. This allows doing the pps_event() work in the polling
routine, instead of using a taskqueue task to do that work.
Also, add PNPINFO, and switch to using make_dev_s() to create the cdev.
Using a spin mutex and calling pps_event() from the polling function works
around the situation which requires more than 2 sets of timecounter
timehands in a single-core system to get reliable PPS capture. That problem
would happen when a single-core system is idle in cpu_idle() then gets woken
up with an event timer event which was scheduled to handle a hardclock tick.
That processing path would end up calling tc_windup 3 or 4 times between
when the tc polling function was called and when the taskqueue task would
eventually run, and with only two sets of timehands, the th_generation count
would always be too old to allow the captured PPS data to be used.
Due to lock ordering issues (bucket lock held, vnode locks wanted) the code
starts with trylocking which in face of contention often fails. Prior to
the change it would loop back with a possible yield.
Instead note we know what locks are needed and can take them in the right
order, avoiding retries. Then we can safely re-lookup and see if the entry
we are looking for is still there.
On a 104-way box poudriere would result in constant retries during an 11h
run as seen in the vfs.cache.zap_and_exit_bucket_fail counter.
before: 408866592
after : 0
However, a new stat reports:
vfs.cache.zap_and_exit_bucket_relock_success: 32638
Note this is only a bandaid over current design issues.
Tested by: pho
Sponsored by: The FreeBSD Foundation
It used to be mp_ncpus * 64, but this gives unnecessarily big values for small
machines and at the same time constraints bigger ones. In particular this helps
on a 104-way box for which the count is now doubled.
While here make cache_purgevfs less likely. Currently it is not efficient in
face of contention due to lock ordering issues. These are fixable but not worth
it at the moment.
Sponsored by: The FreeBSD Foundation
- VM_ALLOC_NOCREAT will grab without creating a page.
- vm_page_grab_valid() will grab and page in if necessary.
- vm_page_busy_acquire() automates some busy acquire loops.
Discussed with: alc, kib, markj
Tested by: pho (part of larger branch)
Sponsored by: Netflix
Differential Revision: https://reviews.freebsd.org/D21546
races with page busy state. The object lock is still used as an interlock
to ensure that the identity stays valid. Most callers should use
vm_page_sleep_if_busy() to handle the locking particulars.
Reviewed by: alc, kib, markj
Sponsored by: Netflix
Differential Revision: https://reviews.freebsd.org/D21255
These commands show the route resolved for a specified destination, or
print out the entire routing table for a given address family (or all
families, if none is explicitly provided).
Discussed with: emaste
Differential Revision: https://reviews.freebsd.org/D21510
There are several mechanisms by which a vm_page reference is held,
preventing the page from being freed back to the page allocator. In
particular, holding the page's object lock is sufficient to prevent the
page from being freed; holding the busy lock or a wiring is sufficent as
well. These references are protected by the page lock, which must
therefore be acquired for many per-page operations. This results in
false sharing since the page locks are external to the vm_page
structures themselves and each lock protects multiple structures.
Transition to using an atomically updated per-page reference counter.
The object's reference is counted using a flag bit in the counter. A
second flag bit is used to atomically block new references via
pmap_extract_and_hold() while removing managed mappings of a page.
Thus, the reference count of a page is guaranteed not to increase if the
page is unbusied, unmapped, and the object's write lock is held. As
a consequence of this, the page lock no longer protects a page's
identity; operations which move pages between objects are now
synchronized solely by the objects' locks.
The vm_page_wire() and vm_page_unwire() KPIs are changed. The former
requires that either the object lock or the busy lock is held. The
latter no longer has a return value and may free the page if it releases
the last reference to that page. vm_page_unwire_noq() behaves the same
as before; the caller is responsible for checking its return value and
freeing or enqueuing the page as appropriate. vm_page_wire_mapped() is
introduced for use in pmap_extract_and_hold(). It fails if the page is
concurrently being unmapped, typically triggering a fallback to the
fault handler. vm_page_wire() no longer requires the page lock and
vm_page_unwire() now internally acquires the page lock when releasing
the last wiring of a page (since the page lock still protects a page's
queue state). In particular, synchronization details are no longer
leaked into the caller.
The change excises the page lock from several frequently executed code
paths. In particular, vm_object_terminate() no longer bounces between
page locks as it releases an object's pages, and direct I/O and
sendfile(SF_NOCACHE) completions no longer require the page lock. In
these latter cases we now get linear scalability in the common scenario
where different threads are operating on different files.
__FreeBSD_version is bumped. The DRM ports have been updated to
accomodate the KPI changes.
Reviewed by: jeff (earlier version)
Tested by: gallatin (earlier version), pho
Sponsored by: Netflix
Differential Revision: https://reviews.freebsd.org/D20486
Allow commands to specify that (hex) numbers may start with A-F, by adding
the DRT_HEX flag for db_read_token_flags(). As before, numbers containing
invalid digits for the current radix are rejected.
Also, lex ':' and '::' tokens as tCOLON and tCOLONCOLON respectively.
There is a mild conflict here with lexed "identifiers" (tIDENT): ddb
identifiers may contain arbitrary colons, and the ddb lexer is greedy. So
the identifier lex will swallow any colons it finds inside identifiers, and
consumers are still unable to expect the token sequence 'tIDENT tCOLON'.
That limitation does not matter for IPv6 addresses, because the lexer always
attempts to lex numbers before identifiers.
Reviewed by: markj
Differential Revision: https://reviews.freebsd.org/D21509
Add a db_read_token_flags() variant of db_read_token() with configurable
parameters.
Allow specifying an explicit radix for tNUMBER lexing. It overrides the
default inference and db_radix setting.
Also provide the option of yielding any lexed whitespace (tWSPACE) (instead
of ignoring it). This is useful for whitespace-sensitive CS_OWN commands.
Reviewed by: markj
Differential Revision: https://reviews.freebsd.org/D21459
This fixes hitting a KASSERT with a valid packet exchange.
Reviewed by: rrs@, Richard Scheffenegger
MFC after: 3 days
Sponsored by: Netflix, Inc.
Differential Revision: https://reviews.freebsd.org/D21567
This makes clearing it (from locore.S) work without misaligned accesses
(which can trap to machine mode, and be slow).
Reviewed by: br
Sponsored by: Axiado
Differential Revision: https://reviews.freebsd.org/D21538
When softdep_fsync() is running, a caller must already started write
for the mount point. Since unmount or remount to ro suspends mount
point, it cannot run in parallel with softdep_fsync(), which makes
vfs_busy() call there not needed.
Doing blocking vfs_busy() there effectively causes lock order reversal
between vn_start_write() and setting MNTK_UNMOUNT, because
vfs_busy(mp, 0) sleeps waiting for MNTK_UNMOUNT becoming clear, while
unmount sets the flag and starts the suspension.
Note that all other uses of vfs_busy() in SU code are non-blocking.
Reported by: chs by mckusick
Reviewed by: mckusick
Tested by: pho
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
The branch from _start to mpentry has to cross a large section of data;
an offset larger than can be specified with a 12-bit branch immediate.
Fix this by converting the branch to an unconditional jump. The gcc
assembler does this conversion silently but it is not done automatically
by clang.
Reported by: Jeremy Bennett <jeremy.bennett@embecosm.com>
Reviewed by: markj
Approved by: markj (mentor)
MFC after: 1 week
Differential Revision: https://reviews.freebsd.org/D21437
Use the -march and -mabi flags for both gcc and clang as they are
compatible. Specify the "medium" code model separately as it goes by the
name "medany" under gcc, although they are equivalent.
Reviewed by: markj
Approved by: markj (mentor)
MFC after: 3 days
Differential Revision: https://reviews.freebsd.org/D21436
Instead of using hardcoded bpp of 24, obtain current/configured value
from VideoCore. This solves certain problems with Xorg/Qt apps that
require bpp of 32 to work properly. The mode can be forced by setting
framebuffer_depth value in config.txt
PR: 235363
Submitted by: Steve Peurifoy <ssw01@mathistry.net>
Otherwise, we might left the boolean set, which would affect cleanup
after an error on interpreter activation.
Reviewed by: markj
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D21560
We track text mappings explicitly, there is no removal of the text
refs on the object deallocate any more, so tmpfs objects should not be
treated specially. Doing so causes excess deref.
Reported and tested by: gallatin
Reviewed by: markj
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D21560
This is a rework of r344701, that noticed that number of bytes passes to
8 bit sector count field gets truncated. First decision was to not pass
anything, since ATA specs define the field as N/A. But it appeared to be a
problem for some SAT devices, that require information about data transfer
to operate properly. Some additional investigation shown that it is quite
a common practice to set unused fields of ATA commands (fortunately ATA
specs formally allow it) to supply the information to SAT layer. I have
found SAS-SATA interposer that does not allow pass-through without it.
As side effect, reduce code duplication by removing ata_do_28bit_cmd()
function, replacing it with more universal ata_do_cmd().
MFC after: 1 week
Sponsored by: iXsystems, Inc.
this to 2k to prevent them from being truncated and ignored. It
appears to be a sanity check only, but bumping it to 2k allows both of
my iic hid devices to be parsed and the second one to work...
CID 1404532 fixes a signed vs unsigned comparison error in fuse_vnop_bmap.
It could potentially have resulted in VOP_BMAP reporting too many
consecutive blocks.
CID 1404364 is much worse. It was an array access by an untrusted,
user-provided variable. It could potentially have resulted in a malicious
file system crashing the kernel or worse.
Reported by: Coverity
Reviewed by: emaste
MFC after: 3 days
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D21466
to add BBR. These changes make it so you can get an
array of timestamps instead of a compressed ack/data segment.
BBR uses this to aid with its delivery estimates. We also
now (via Drew's suggestions) will not go to the expense of
the tcb lookup if no stack registers to want this feature. If
HPTS is not present the feature is not present either and you
just get the compressed behavior.
Sponsored by: Netflix Inc
Differential Revision: https://reviews.freebsd.org/D21127
We only call alloc_pvo_entry() with M_WAITOK from one location. However,
this can be called while holding nonsleepable locks. Rather than passing
M_WAITOK down, use vm_wait() and loop.
