Commit Graph

247 Commits

Author SHA1 Message Date
Mark Johnston
afa5d70339 Release the second critical section in uma_zfree_arg() slightly earlier.
It is only needed when removing a full bucket from the per-CPU cache. The
bucket cache (uz_buckets) is protected by the zone mutex and thus the
critical section can be released before inserting into that list.

MFC after:	1 week
2016-07-20 01:01:50 +00:00
Nathan Whitehorn
96c85efb4b Replace a number of conflations of mp_ncpus and mp_maxid with either
mp_maxid or CPU_FOREACH() as appropriate. This fixes a number of places in
the kernel that assumed CPU IDs are dense in [0, mp_ncpus) and would try,
for example, to run tasks on CPUs that did not exist or to allocate too
few buffers on systems with sparse CPU IDs in which there are holes in the
range and mp_maxid > mp_ncpus. Such circumstances generally occur on
systems with SMT, but on which SMT is disabled. This patch restores system
operation at least on POWER8 systems configured in this way.

There are a number of other places in the kernel with potential problems
in these situations, but where sparse CPU IDs are not currently known
to occur, mostly in the ARM machine-dependent code. These will be fixed
in a follow-up commit after the stable/11 branch.

PR:		kern/210106
Reviewed by:	jhb
Approved by:	re (glebius)
2016-07-06 14:09:49 +00:00
Mark Johnston
bc9d08e1cf Fix memguard(9) in kernels with INVARIANTS enabled.
With r284861, UMA zones use the trash ctor and dtor by default. This is
incompatible with memguard, which frees the backing page when the item
is freed. Modify the UMA debug functions to be no-ops if the item was
allocated from memguard. This also fixes constructors such as
mb_ctor_pack(), which invokes the trash ctor in addition to performing
some initialization.

Reviewed by:	glebius
MFC after:	3 weeks
Differential Revision:	https://reviews.freebsd.org/D6562
2016-06-01 22:31:35 +00:00
Pedro F. Giffuni
763df3ec55 sys/vm: minor spelling fixes in comments.
No functional change.
2016-05-02 20:16:29 +00:00
Gleb Smirnoff
cfcae3f86f Remove UMA_ZONE_REFCNT feature, now unused.
Blessed by:	jeff
2016-03-01 00:33:32 +00:00
Gleb Smirnoff
e60b2fcbeb Redo r292484. Embed task(9) into zone, so that uz_maxaction is called
in a context that can sleep, allowing consumers of the KPI to run their
drain routines without any extra measures.

Discussed with:	jtl
2016-02-03 23:30:17 +00:00
Gleb Smirnoff
9542ea7b80 Move uma_dbg_alloc() and uma_dbg_free() into uma_core.c, which allows
to make uma_dbg.h not depend on uma_int.h, which allows to uninclude
uma_int.h from the mbuf(9) allocator.
2016-02-03 22:02:36 +00:00
Jonathan T. Looney
54503a13d8 Add a safety net to reclaim mbufs when one of the mbuf zones become
exhausted.

It is possible for a bug in the code (or, theoretically, even unusual
network conditions) to exhaust all possible mbufs or mbuf clusters.
When this occurs, things can grind to a halt fairly quickly. However,
we currently do not call mb_reclaim() unless the entire system is
experiencing a low-memory condition.

While it is best to try to prevent exhaustion of one of the mbuf zones,
it would also be useful to have a mechanism to attempt to recover from
these situations by freeing "expendable" mbufs.

This patch makes two changes:

a) The patch adds a generic API to the UMA zone allocator to set a
function that should be called when an allocation fails because the
zone limit has been reached. Because of the way this function can be
called, it really should do minimal work.

b) The patch uses this API to try to free mbufs when an allocation
fails from one of the mbuf zones because the zone limit has been
reached. The function schedules a callout to run mb_reclaim().

Differential Revision:	https://reviews.freebsd.org/D3864
Reviewed by:	gnn
Comments by:	rrs, glebius
MFC after:	2 weeks
Sponsored by:	Juniper Networks
2015-12-20 02:05:33 +00:00
Mark Johnston
d9e2e68d38 Don't make assertions about td_critnest when the scheduler is stopped.
A panicking thread always executes with a critical section held, so any
attempt to allocate or free memory while dumping will otherwise cause a
second panic. This can occur, for example, if xpt_polled_action() completes
non-dump I/O that was pending at the time of the panic. The fact that this
can occur is itself a bug, but asserting in this case does little but
reduce the reliability of kernel dumps.

Suggested by:	kib
Reported by:	pho
2015-12-11 20:05:07 +00:00
Jonathan T. Looney
1067a2ba68 Consistently enforce the restriction against calling malloc/free when in a
critical section.

uma_zalloc_arg()/uma_zalloc_free() may acquire a sleepable lock on the
zone. The malloc() family of functions may call uma_zalloc_arg() or
uma_zalloc_free().

The malloc(9) man page currently claims that free() will never sleep.
It also implies that the malloc() family of functions will not sleep
when called with M_NOWAIT. However, it is more correct to say that
these functions will not sleep indefinitely. Indeed, they may acquire
a sleepable lock. However, a developer may overlook this restriction
because the WITNESS check that catches attempts to call the malloc()
family of functions within a critical section is inconsistenly
applied.

This change clarifies the language of the malloc(9) man page to clarify
the restriction against calling the malloc() family of functions
while in a critical section or holding a spin lock. It also adds
KASSERTs at appropriate points to make the enforcement of this
restriction more consistent.

PR:		204633
Differential Revision:	https://reviews.freebsd.org/D4197
Reviewed by:	markj
Approved by:	gnn (mentor)
Sponsored by:	Juniper Networks
2015-11-19 14:04:53 +00:00
Alan Cox
087a613247 Exploit r288122 to address a cosmetic issue. Since the pages allocated
by noobj_alloc() don't belong to a vm object, they can't be paged out.
Since they can't be paged out, they are never enqueued in a paging queue.
Nonetheless, passing PQ_INACTIVE to vm_page_unwire() creates the appearance
that these pages are being enqueued in the inactive queue.  As of r288122,
we can avoid giving this false impression by passing PQ_NONE.

Submitted by:	kmacy
Differential Revision:	https://reviews.freebsd.org/D1674
2015-09-26 17:45:10 +00:00
Mateusz Guzik
19c591bfe2 Don't trash memory from UMA_ZONE_NOFREE zones.
Objects obtained from such zones are supposed to retain type stability,
which was violated by aforementioned trashing.

This is a follow-up to r284861.

Discussed with:		kib
2015-09-02 23:09:01 +00:00
Mark Murray
e866d8f05b Make the UMA harvesting go away completely if not wanted. Default to "not wanted".
Provide and document the RANDOM_ENABLE_UMA option.

Change RANDOM_FAST to RANDOM_UMA to clarify the harvesting.

Remove RANDOM_DEBUG option, replace with SDT probes. These will be of
use to folks measuring the harvesting effect when deciding whether to
use RANDOM_ENABLE_UMA.

Requested by:	scottl and others.
Approved by:	so (/dev/random blanket)
Differential Revision:    https://reviews.freebsd.org/D3197
2015-08-22 12:59:05 +00:00
Zbigniew Bodek
9ba30bcb42 Avoid sign extension of value passed to kva_alloc from uma_zone_reserve_kva
Fixes "panic: vm_radix_reserve_kva: unable to reserve KVA" caused by sign
extention of "pages * UMA_SLAB_SIZE" value passed to kva_alloc() which
takes unsigned long argument.

In the erroneus case that triggered this bug, the number of pages
to allocate in uma_zone_reserve_kva() was 0x8ebe6, that gave the
total number of bytes to allocate equal to 0x8ebe6000 (int).
This was then sign extended in kva_alloc() to 0xffffffff8ebe6000
(unsigned long).

Reviewed by:   alc, kib
Submitted by:  Zbigniew Bodek <zbb@semihalf.com>
Obtained from: Semihalf
Sponsored by:  The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D3346
2015-08-10 17:16:49 +00:00
Mark Murray
d1b06863fb Huge cleanup of random(4) code.
* GENERAL
- Update copyright.
- Make kernel options for RANDOM_YARROW and RANDOM_DUMMY. Set
  neither to ON, which means we want Fortuna
- If there is no 'device random' in the kernel, there will be NO
  random(4) device in the kernel, and the KERN_ARND sysctl will
  return nothing. With RANDOM_DUMMY there will be a random(4) that
  always blocks.
- Repair kern.arandom (KERN_ARND sysctl). The old version went
  through arc4random(9) and was a bit weird.
- Adjust arc4random stirring a bit - the existing code looks a little
  suspect.
- Fix the nasty pre- and post-read overloading by providing explictit
  functions to do these tasks.
- Redo read_random(9) so as to duplicate random(4)'s read internals.
  This makes it a first-class citizen rather than a hack.
- Move stuff out of locked regions when it does not need to be
  there.
- Trim RANDOM_DEBUG printfs. Some are excess to requirement, some
  behind boot verbose.
- Use SYSINIT to sequence the startup.
- Fix init/deinit sysctl stuff.
- Make relevant sysctls also tunables.
- Add different harvesting "styles" to allow for different requirements
  (direct, queue, fast).
- Add harvesting of FFS atime events. This needs to be checked for
  weighing down the FS code.
- Add harvesting of slab allocator events. This needs to be checked for
  weighing down the allocator code.
- Fix the random(9) manpage.
- Loadable modules are not present for now. These will be re-engineered
  when the dust settles.
- Use macros for locks.
- Fix comments.

* src/share/man/...
- Update the man pages.

* src/etc/...
- The startup/shutdown work is done in D2924.

* src/UPDATING
- Add UPDATING announcement.

* src/sys/dev/random/build.sh
- Add copyright.
- Add libz for unit tests.

* src/sys/dev/random/dummy.c
- Remove; no longer needed. Functionality incorporated into randomdev.*.

* live_entropy_sources.c live_entropy_sources.h
- Remove; content moved.
- move content to randomdev.[ch] and optimise.

* src/sys/dev/random/random_adaptors.c src/sys/dev/random/random_adaptors.h
- Remove; plugability is no longer used. Compile-time algorithm
  selection is the way to go.

* src/sys/dev/random/random_harvestq.c src/sys/dev/random/random_harvestq.h
- Add early (re)boot-time randomness caching.

* src/sys/dev/random/randomdev_soft.c src/sys/dev/random/randomdev_soft.h
- Remove; no longer needed.

* src/sys/dev/random/uint128.h
- Provide a fake uint128_t; if a real one ever arrived, we can use
  that instead. All that is needed here is N=0, N++, N==0, and some
  localised trickery is used to manufacture a 128-bit 0ULLL.

* src/sys/dev/random/unit_test.c src/sys/dev/random/unit_test.h
- Improve unit tests; previously the testing human needed clairvoyance;
  now the test will do a basic check of compressibility. Clairvoyant
  talent is still a good idea.
- This is still a long way off a proper unit test.

* src/sys/dev/random/fortuna.c src/sys/dev/random/fortuna.h
- Improve messy union to just uint128_t.
- Remove unneeded 'static struct fortuna_start_cache'.
- Tighten up up arithmetic.
- Provide a method to allow eternal junk to be introduced; harden
  it against blatant by compress/hashing.
- Assert that locks are held correctly.
- Fix the nasty pre- and post-read overloading by providing explictit
  functions to do these tasks.
- Turn into self-sufficient module (no longer requires randomdev_soft.[ch])

* src/sys/dev/random/yarrow.c src/sys/dev/random/yarrow.h
- Improve messy union to just uint128_t.
- Remove unneeded 'staic struct start_cache'.
- Tighten up up arithmetic.
- Provide a method to allow eternal junk to be introduced; harden
  it against blatant by compress/hashing.
- Assert that locks are held correctly.
- Fix the nasty pre- and post-read overloading by providing explictit
  functions to do these tasks.
- Turn into self-sufficient module (no longer requires randomdev_soft.[ch])
- Fix some magic numbers elsewhere used as FAST and SLOW.

Differential Revision: https://reviews.freebsd.org/D2025
Reviewed by: vsevolod,delphij,rwatson,trasz,jmg
Approved by: so (delphij)
2015-06-30 17:00:45 +00:00
John-Mark Gurney
afc6dc3669 If INVARIANTS is specified, add ctor/dtor to junk memory if they are
unspecified...

Submitted by:	Suresh Gumpula at Netapp
Differential Revision:	https://reviews.freebsd.org/D2725
2015-06-25 20:44:46 +00:00
Jung-uk Kim
fd90e2ed54 CALLOUT_MPSAFE has lost its meaning since r141428, i.e., for more than ten
years for head.  However, it is continuously misused as the mpsafe argument
for callout_init(9).  Deprecate the flag and clean up callout_init() calls
to make them more consistent.

Differential Revision:	https://reviews.freebsd.org/D2613
Reviewed by:	jhb
MFC after:	2 weeks
2015-05-22 17:05:21 +00:00
Konstantin Belousov
44ec2b63c5 The vmem callback to reclaim kmem arena address space on low or
fragmented conditions currently just wakes up the pagedaemon.  The
kmem arena is significantly smaller then the total available physical
memory, which means that there are loads where kmem arena space could
be exhausted, while there is a lot of pages available still.  The
woken up pagedaemon sees vm_pages_needed != 0, verifies the condition
vm_paging_needed() which is false, clears the pass and returns back to
sleep, not calling neither uma_reclaim() nor lowmem handler.

To handle low kmem arena conditions, create additional pagedaemon
thread which calls uma_reclaim() directly.  The thread sleeps on the
dedicated channel and kmem_reclaim() wakes the thread in addition to
the pagedaemon.

Reported and tested by:	pho
Sponsored by:	The FreeBSD Foundation
MFC after:	2 weeks
2015-05-09 20:08:36 +00:00
Alan Cox
d74e6a1d27 Eliminate an unused variable.
MFC after:	1 week
2015-04-20 16:48:21 +00:00
Dmitry Chagin
51cfb0be84 Rework r281162. Indeed, the flexible array member is preferable here.
Suggested by:   Justin T. Gibbs

MFC after:	3 days
2015-04-12 06:21:58 +00:00
Gleb Smirnoff
16be9f54e7 UMA zone limit can be lowered, so remove protection against from
the sysctl_handle_uma_zone_max().

Sponsored by:	Nginx, Inc.
2015-04-10 06:56:49 +00:00
Dmitry Chagin
6723fdfe46 Properly calculate "UMA Zones" per cpu cache size. Avoid allocating
an extra struct uma_cache since the struct uma_zone already has one.

PR:		199169
Submitted by:	luke.tw gmail com
MFC after:	1 week
2015-04-06 18:45:41 +00:00
Dmitry Chagin
1d2c0c460c Fix wrong kassert msg in uma.
PR:		199172
Submitted by:	luke.tw gmail com
MFC after:	1 week
2015-04-05 18:25:23 +00:00
Ryan Stone
f2c2231e0c Fix integer truncation bug in malloc(9)
A couple of internal functions used by malloc(9) and uma truncated
a size_t down to an int.  This could cause any number of issues
(e.g. indefinite sleeps, memory corruption) if any kernel
subsystem tried to allocate 2GB or more through malloc.  zfs would
attempt such an allocation when run on a system with 2TB or more
of RAM.

Note to self: When this is MFCed, sparc64 needs the same fix.

Differential revision:	https://reviews.freebsd.org/D2106
Reviewed by:	kib
Reported by:	Michael Fuckner <michael@fuckner.net>
Tested by:	Michael Fuckner <michael@fuckner.net>
MFC after:	2 weeks
2015-04-01 12:42:26 +00:00
Ian Lepore
1eafc07856 Set the SBUF_INCLUDENUL flag in sbuf_new_for_sysctl() so that sysctl
strings returned to userland include the nulterm byte.

Some uses of sbuf_new_for_sysctl() write binary data rather than strings;
clear the SBUF_INCLUDENUL flag after calling sbuf_new_for_sysctl() in
those cases.  (Note that the sbuf code still automatically adds a nulterm
byte in sbuf_finish(), but since it's not included in the length it won't
get copied to userland along with the binary data.)

Remove explicit adding of a nulterm byte in a couple places now that it
gets done automatically by the sbuf drain code.

PR:		195668
2015-03-14 17:08:28 +00:00
Alan Cox
67c44fa359 Eliminate a stale debug message. The per-CPU cache locks were replaced
by critical sections in r145686.

PR:		193254
Submitted by:	luke.tw@gmail.com
MFC after:	3 days
2014-12-31 17:44:57 +00:00
Konstantin Belousov
95c4bf756a Provide mutual exclusion between zone allocation/destruction and
uma_reclaim().  Reclamation code must not see half-constructed or
destructed zones.  Do this by bracing uma_zcreate() and uma_zdestroy()
into a shared-locked sx, and take the sx exclusively in uma_reclaim().

Usually zones are not created/destroyed during the system operation,
but tmpfs mounts do cause zone operations and exposed the bug.

Another solution could be to only expose a new keg on uma_kegs list
after the corresponding zone is fully constructed, and similar
treatment for the destruction.  But it probably requires more risky
code rearrangement as well.

Reported and tested by:	pho
Discussed with:	avg
Sponsored by:	The FreeBSD Foundation
MFC after:	2 weeks
2014-11-30 20:20:55 +00:00
Mark Murray
10cb24248a This is the much-discussed major upgrade to the random(4) device, known to you all as /dev/random.
This code has had an extensive rewrite and a good series of reviews, both by the author and other parties. This means a lot of code has been simplified. Pluggable structures for high-rate entropy generators are available, and it is most definitely not the case that /dev/random can be driven by only a hardware souce any more. This has been designed out of the device. Hardware sources are stirred into the CSPRNG (Yarrow, Fortuna) like any other entropy source. Pluggable modules may be written by third parties for additional sources.

The harvesting structures and consequently the locking have been simplified. Entropy harvesting is done in a more general way (the documentation for this will follow). There is some GREAT entropy to be had in the UMA allocator, but it is disabled for now as messing with that is likely to annoy many people.

The venerable (but effective) Yarrow algorithm, which is no longer supported by its authors now has an alternative, Fortuna. For now, Yarrow is retained as the default algorithm, but this may be changed using a kernel option. It is intended to make Fortuna the default algorithm for 11.0. Interested parties are encouraged to read ISBN 978-0-470-47424-2 "Cryptography Engineering" By Ferguson, Schneier and Kohno for Fortuna's gory details. Heck, read it anyway.

Many thanks to Arthur Mesh who did early grunt work, and who got caught in the crossfire rather more than he deserved to.

My thanks also to folks who helped me thresh this out on whiteboards and in the odd "Hallway track", or otherwise.

My Nomex pants are on. Let the feedback commence!

Reviewed by:	trasz,des(partial),imp(partial?),rwatson(partial?)
Approved by:	so(des)
2014-10-30 21:21:53 +00:00
Bryan Venteicher
111fbcd5ed Change the UMA mutex into a rwlock
Acquire the lock in read mode when just needed to ensure the stability
of the keg list. The UMA lock may be held for a long time (relatively
speaking) in uma_reclaim() on machines with lots of zones/kegs. If the
uma_timeout() would fire during that period, subsequent callouts on that
CPU may be significantly delayed.

Reviewed by:	jhb
2014-10-05 21:34:56 +00:00
Bryan Venteicher
6e5254e0d7 Remove stray uma_mtx lock/unlock in zone_drain_wait()
Callers of zone_drain_wait(M_WAITOK) do not need to hold (and were not)
the uma_mtx, but we would attempt to unlock and relock the mutex if we
had to sleep because the zone was already draining. The M_NOWAIT callers
may hold the uma_mtx, but we do not sleep in that case.

Reviewed by:	jhb
MFC after:	3 days
2014-10-05 03:18:30 +00:00
Hans Petter Selasky
af3b2549c4 Pull in r267961 and r267973 again. Fix for issues reported will follow. 2014-06-28 03:56:17 +00:00
Glen Barber
37a107a407 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
2014-06-27 22:05:21 +00:00
Hans Petter Selasky
3da1cf1e88 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
2014-06-27 16:33:43 +00:00
Attilio Rao
3ae10f7477 - Modify vm_page_unwire() and vm_page_enqueue() to directly accept
the queue where to enqueue pages that are going to be unwired.
- Add stronger checks to the enqueue/dequeue for the pagequeues when
  adding and removing pages to them.

Of course, for unmanaged pages the queue parameter of vm_page_unwire() will
be ignored, just as the active parameter today.
This makes adding new pagequeues quicker.

This change effectively modifies the KPI.  __FreeBSD_version will be,
however, bumped just when the full cache of free pages will be
evicted.

Sponsored by:	EMC / Isilon storage division
Reviewed by:	alc
Tested by:	pho
2014-06-16 18:15:27 +00:00
Alexander Motin
1aa6c75827 Introduce new "256 Bucket" zone to split requests and reduce congestion
on "128 Bucket" zone lock.

MFC after:	2 weeks
Sponsored by:	iXsystems, Inc.
2014-06-12 11:57:07 +00:00
Alexander Motin
20d3ab87cd Allocating new bucket for bucket zone, never take it from the zone itself,
since it will almost certanly fail.  Take next bigger zone instead.

This situation should not happen with original bucket zones configuration:
"32 Bucket" zone uses "64 Bucket" and vice versa.  But if "64 Bucket" zone
lock is congested, zone may grow its bucket size and start biting itself.

MFC after:	2 weeks
Sponsored by:	iXsystems, Inc.
2014-06-12 11:36:22 +00:00
Dimitry Andric
2367b4ddc4 After r251709, avoid a clang 3.4 warning about an unused static const
variable (uma_max_ipers), when asserts are disabled.

Reviewed by:	glebius
MFC after:	3 days
2014-02-14 17:47:18 +00:00
Gleb Smirnoff
48343a2f34 Make M_ZERO flag work correctly on UMA_ZONE_PCPU zones.
Sponsored by:	Nginx, Inc.
2014-02-10 19:48:26 +00:00
Gleb Smirnoff
0a5a3ccb81 Provide macros that allow easily export uma(9) zone limits and
current usage via sysctl(9):

  SYSCTL_UMA_MAX()
  SYSCTL_ADD_UMA_MAX()
  SYSCTL_UMA_CUR()
  SYSCTL_ADD_UMA_CUR()

Sponsored by:	Nginx, Inc.
2014-02-07 14:29:03 +00:00
Craig Rodrigues
a3845534a0 In keg_dtor(), print out the keg name in the "Freed UMA keg was not empty"
message printed to the console.  This makes it easier to track down
the source of certain memory leaks.

Suggested by: adrian
2013-11-29 08:04:45 +00:00
Alexander Motin
03175483c2 - Add bucket size column to show uma DDB command.
- Add `show umacache` command to show alike stats for cache-only UMA zones.
2013-11-28 19:20:49 +00:00
Alexander Motin
cec48e002a Make UMA to not blindly force offpage slab header allocation for large
(> PAGE_SIZE) zones.  If zone is not multiple to PAGE_SIZE, there may
be enough space for the header at the last page, so we may avoid extra
header memory allocation and hash table update/lookup.

ZFS creates bunch of odd-sized UMA zones (5120, 6144, 7168, 10240, 14336).
This change gives good use to at least some of otherwise lost memory there.

Reviewed by:	avg
2013-11-27 20:56:10 +00:00
Alexander Motin
f7104ccd94 Don't count bucket allocation failures for UMA zones as their own failures.
There are good reasons for this to happen, such as recursion prevention, etc.
and they are not fatal since buckets are just an optimization mechanism.
Real bucket allocation failures are any way counted by the bucket zones
themselves, and we don't need double accounting there.
2013-11-27 20:16:18 +00:00
Alexander Motin
e8a720fe60 Fix bug introduced at r252226, when udata argument passed to bucket_alloc()
was used without making sure first that it was really passed for us.

On some of my systems this bug made user argument passed by ZFS code to
uma_zalloc_arg() unexpectedly block UMA per-CPU caches for those zones.
2013-11-27 19:55:42 +00:00
Alexander Motin
8a8d9d1475 When purging per-CPU UMA caches do not return empty buckets into the global
full bucket cache to not trigger assertion if allocation happen before that
global cache get purged.
2013-11-23 13:42:56 +00:00
Alexander Motin
a2de44abf5 Implement mechanism to safely but slowly purge UMA per-CPU caches.
This is a last resort for very low memory condition in case other measures
to free memory were ineffective.  Sequentially cycle through all CPUs and
extract per-CPU cache buckets into zone cache from where they can be freed.
2013-11-19 10:51:46 +00:00
Alexander Motin
4d104ba024 Grow UMA zone bucket size also on lock congestion during item free.
Lock congestion is the same, whether it happens on alloc or free, so
handle it equally.  Now that we have back pressure, there is no problem
to grow buckets a bit faster.  Any way growth is much slower then in 9.x.
2013-11-19 10:17:10 +00:00
Alexander Motin
f3932e9025 Add two new UMA bucket zones to store 3 and 9 items per bucket.
These new buckets make bucket size self-tuning more soft and precise.
Without them there are buckets for 1, 5, 13, 29, ... items.  While at
bigger sizes difference about 2x is fine, at smallest ones it is 5x and
2.6x respectively.  New buckets make that line look like 1, 3, 5, 9, 13,
29, reducing jumps between steps, making algorithm work softer, allocating
and freeing memory in better fitting chunks.  Otherwise there is quite a
big gap between allocating 128K and 5x128K of RAM at once.
2013-11-19 10:10:44 +00:00
Alexander Motin
ace66b568e Implement soft pressure on UMA cache bucket sizes.
Every time system detects low memory condition decrease bucket sizes for
each zone by one item.  As result, higher memory pressure will push to
smaller bucket sizes and so smaller per-CPU caches and so more efficient
memory use.

Before this change there was no force to oppose buckets growth as result
of practically inevitable zone lock conflicts, and after some run time
per-CPU caches could consume enough RAM to kill the system.
2013-11-19 10:05:53 +00:00
Kirk McKusick
1645995b97 Fix bug introduced in rewrite of keg_free_slab in -r251894.
The consequence of the bug is that fini calls are not done
when a slab is freed by a call-back from the page daemon.
It went unnoticed for two months because fini is little used.

I spotted the bug while reading the code to learn how it works
so I could write it up for the next edition of the Design and
Implementation of FreeBSD book.

No MFC needed as this code exists only in HEAD.

Reviewed by: kib, jeff
Tested by:   pho
2013-08-31 15:40:15 +00:00