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In situations where objects are rapidly allocated from the pool and handed
back, the size of the per CPU pool turns out to be too small.
Double the size of the per CPU pool.
This reduces the kmem cache allocation and free operations during a kernel compile:
alloc free
Baseline: 380k 330k
Double size: 295k 245k
Especially the reduction of allocations is important because that happens
in the hot path when objects are initialized.
The maximum increase in per CPU pool memory consumption is about 2.5K per
online CPU, which is acceptable.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Zhen Lei <thunder.leizhen@huawei.com>
Link: https://lore.kernel.org/all/20241007164914.378676302@linutronix.de
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Keep it along with the pool as that's a hot cache line anyway and it makes
the code more comprehensible.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Zhen Lei <thunder.leizhen@huawei.com>
Link: https://lore.kernel.org/all/20241007164914.318776207@linutronix.de
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Adding and removing single objects in a loop is bad in terms of lock
contention and cache line accesses.
To implement batching, record the last object in a batch in the object
itself. This is trivialy possible as hlists are strictly stacks. At a batch
boundary, when the first object is added to the list the object stores a
pointer to itself in debug_obj::batch_last. When the next object is added
to the list then the batch_last pointer is retrieved from the first object
in the list and stored in the to be added one.
That means for batch processing the first object always has a pointer to
the last object in a batch, which allows to move batches in a cache line
efficient way and reduces the lock held time.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Zhen Lei <thunder.leizhen@huawei.com>
Link: https://lore.kernel.org/all/20241007164914.258995000@linutronix.de
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Allocate a batch and then push it into the pool. Utilize the
debug_obj::last_node pointer for keeping track of the batch boundary.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/20241007164914.198647184@linutronix.de
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Move the debug_obj::object pointer into a union and add a pointer to the
last node in a batch. That allows to implement batch processing efficiently
by utilizing the stack property of hlist:
When the first object of a batch is added to the list, then the batch
pointer is set to the hlist node of the object itself. Any subsequent add
retrieves the pointer to the last node from the first object in the list
and uses that for storing the last node pointer in the newly added object.
Add the pointer to the data structure and ensure that all relevant pool
sizes are strictly batch sized. The actual batching implementation follows
in subsequent changes.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Zhen Lei <thunder.leizhen@huawei.com>
Link: https://lore.kernel.org/all/20241007164914.139204961@linutronix.de
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Get rid of the conditional in the hot path.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Zhen Lei <thunder.leizhen@huawei.com>
Link: https://lore.kernel.org/all/20241007164914.077247071@linutronix.de
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Convert it to batch processing with intermediate helper functions. This
reduces the final changes for batch processing.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Zhen Lei <thunder.leizhen@huawei.com>
Link: https://lore.kernel.org/all/20241007164914.015906394@linutronix.de
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__free_object() is uncomprehensibly complex. The same can be achieved by:
1) Adding the object to the per CPU pool
2) If that pool is full, move a batch of objects into the global pool
or if the global pool is full into the to free pool
This also prepares for batch processing.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Zhen Lei <thunder.leizhen@huawei.com>
Link: https://lore.kernel.org/all/20241007164913.955542307@linutronix.de
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The current allocation scheme tries to allocate from the per CPU pool
first. If that fails it allocates one object from the global pool and then
refills the per CPU pool from the global pool.
That is in the way of switching the pool management to batch mode as the
global pool needs to be a strict stack of batches, which does not allow
to allocate single objects.
Rework the code to refill the per CPU pool first and then allocate the
object from the refilled batch. Also try to allocate from the to free pool
first to avoid freeing and reallocating objects.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Zhen Lei <thunder.leizhen@huawei.com>
Link: https://lore.kernel.org/all/20241007164913.893554162@linutronix.de
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Having the accounting in the datastructure is better in terms of cache
lines and allows more optimizations later on.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Zhen Lei <thunder.leizhen@huawei.com>
Link: https://lore.kernel.org/all/20241007164913.831908427@linutronix.de
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No point in having a separate data structure. Reuse struct obj_pool and
tidy up the code.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Zhen Lei <thunder.leizhen@huawei.com>
Link: https://lore.kernel.org/all/20241007164913.770595795@linutronix.de
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There is no point to handle the statically allocated objects during early
boot in the actual pool list. This phase does not require accounting, so
all of the related complexity can be avoided.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Zhen Lei <thunder.leizhen@huawei.com>
Link: https://lore.kernel.org/all/20241007164913.708939081@linutronix.de
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The contention on the global pool lock can be reduced by strict batch
processing where batches of objects are moved from one list head to another
instead of moving them object by object. This also reduces the cache
footprint because it avoids the list walk and dirties at maximum three
cache lines instead of potentially up to eighteen.
To prepare for that, move the hlist head and related counters into a
struct.
No functional change.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Zhen Lei <thunder.leizhen@huawei.com>
Link: https://lore.kernel.org/all/20241007164913.646171170@linutronix.de
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The contention on the global pool_lock can be massive when the global pool
needs to be refilled and many CPUs try to handle this.
Address this by:
- splitting the refill from free list and allocation.
Refill from free list has no constraints vs. the context on RT, so
it can be tried outside of the RT specific preemptible() guard
- Let only one CPU handle the free list
- Let only one CPU do allocations unless the pool level is below
half of the minimum fill level.
Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/20240911083521.2257-4-thunder.leizhen@huawei.com-
Link: https://lore.kernel.org/all/20241007164913.582118421@linutronix.de
--
lib/debugobjects.c | 84 +++++++++++++++++++++++++++++++++++++----------------
1 file changed, 59 insertions(+), 25 deletions(-)
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Make it what it is.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Zhen Lei <thunder.leizhen@huawei.com>
Link: https://lore.kernel.org/all/20241007164913.518175013@linutronix.de
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Move the loop to free a list of objects into a helper function so it can be
reused later.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/20241007164913.453912357@linutronix.de
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It has zero value.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Zhen Lei <thunder.leizhen@huawei.com>
Link: https://lore.kernel.org/all/20241007164913.390511021@linutronix.de
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Reuse the helper function instead of having a open coded copy.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Zhen Lei <thunder.leizhen@huawei.com>
Link: https://lore.kernel.org/all/20241007164913.326834268@linutronix.de
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Freeing the per CPU pool of the unplugged CPU directly is suboptimal as the
objects can be reused in the real pool if there is room. Aside of that this
gets the accounting wrong.
Use the regular free path, which allows reuse and has the accounting correct.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Zhen Lei <thunder.leizhen@huawei.com>
Link: https://lore.kernel.org/all/20241007164913.263960570@linutronix.de
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It's BSS zero initialized.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Zhen Lei <thunder.leizhen@huawei.com>
Link: https://lore.kernel.org/all/20241007164913.200379308@linutronix.de
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debug_objects_mem_init() is invoked from mm_core_init() before work queues
are available. If debug_objects_mem_init() destroys the kmem cache in the
error path it causes an Oops in __queue_work():
Oops: Oops: 0000 [#1] PREEMPT SMP PTI
RIP: 0010:__queue_work+0x35/0x6a0
queue_work_on+0x66/0x70
flush_all_cpus_locked+0xdf/0x1a0
__kmem_cache_shutdown+0x2f/0x340
kmem_cache_destroy+0x4e/0x150
mm_core_init+0x9e/0x120
start_kernel+0x298/0x800
x86_64_start_reservations+0x18/0x30
x86_64_start_kernel+0xc5/0xe0
common_startup_64+0x12c/0x138
Further the object cache pointer is used in various places to check for
early boot operation. It is exposed before the replacments for the static
boot time objects are allocated and the self test operates on it.
This can be avoided by:
1) Running the self test with the static boot objects
2) Exposing it only after the replacement objects have been added to
the pool.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/20241007164913.137021337@linutronix.de
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Collect the newly allocated debug objects in a list outside the lock, so
that the lock held time and the potential lock contention is reduced.
Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/20240911083521.2257-3-thunder.leizhen@huawei.com
Link: https://lore.kernel.org/all/20241007164913.073653668@linutronix.de
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The statically allocated objects are all located in obj_static_pool[],
the whole memory of obj_static_pool[] will be reclaimed later. Therefore,
there is no need to split the remaining statically nodes in list obj_pool
into isolated ones, no one will use them anymore. Just write
INIT_HLIST_HEAD(&obj_pool) is enough. Since hlist_move_list() directly
discards the old list, even this can be omitted.
Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/20240911083521.2257-2-thunder.leizhen@huawei.com
Link: https://lore.kernel.org/all/20241007164913.009849239@linutronix.de
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The cpu_emergency_register_virt_callback() function is used
unconditionally by the x86 kvm code, but it is declared (and defined)
conditionally:
#if IS_ENABLED(CONFIG_KVM_INTEL) || IS_ENABLED(CONFIG_KVM_AMD)
void cpu_emergency_register_virt_callback(cpu_emergency_virt_cb *callback);
...
leading to a build error when neither KVM_INTEL nor KVM_AMD support is
enabled:
arch/x86/kvm/x86.c: In function ‘kvm_arch_enable_virtualization’:
arch/x86/kvm/x86.c:12517:9: error: implicit declaration of function ‘cpu_emergency_register_virt_callback’ [-Wimplicit-function-declaration]
12517 | cpu_emergency_register_virt_callback(kvm_x86_ops.emergency_disable_virtualization_cpu);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
arch/x86/kvm/x86.c: In function ‘kvm_arch_disable_virtualization’:
arch/x86/kvm/x86.c:12522:9: error: implicit declaration of function ‘cpu_emergency_unregister_virt_callback’ [-Wimplicit-function-declaration]
12522 | cpu_emergency_unregister_virt_callback(kvm_x86_ops.emergency_disable_virtualization_cpu);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Fix the build by defining empty helper functions the same way the old
cpu_emergency_disable_virtualization() function was dealt with for the
same situation.
Maybe we could instead have made the call sites conditional, since the
callers (kvm_arch_{en,dis}able_virtualization()) have an empty weak
fallback. I'll leave that to the kvm people to argue about, this at
least gets the build going for that particular config.
Fixes: 590b09b1d88e ("KVM: x86: Register "emergency disable" callbacks when virt is enabled")
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Sean Christopherson <seanjc@google.com>
Cc: Kai Huang <kai.huang@intel.com>
Cc: Chao Gao <chao.gao@intel.com>
Cc: Farrah Chen <farrah.chen@intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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The isomorphism neg_if_exp negates the test of a ?: conditional,
making it unnecessary to have an explicit case for a negated test
with the branches inverted.
At the same time, we can disable neg_if_exp in cases where a
different API function may be more suitable for a negated test.
Finally, in the non-patch cases, E matches an expression with
parentheses around it, so there is no need to mention ()
explicitly in the pattern. The () are still needed in the patch
cases, because we want to drop them, if they are present.
Signed-off-by: Julia Lawall <Julia.Lawall@inria.fr>
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The parentheses are only needed if there is a disjunction, ie a
set of possible changes. If there is only one pattern, we can
remove these parentheses. Just like the format:
- x
+ y
not:
(
- x
+ y
)
Signed-off-by: Hongbo Li <lihongbo22@huawei.com>
Signed-off-by: Julia Lawall <Julia.Lawall@inria.fr>
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As other rules done, we add rules for str_yes_no()
to check the relative opportunities.
Signed-off-by: Hongbo Li <lihongbo22@huawei.com>
Signed-off-by: Julia Lawall <Julia.Lawall@inria.fr>
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As other rules done, we add rules for str_on_off()
to check the relative opportunities.
Signed-off-by: Hongbo Li <lihongbo22@huawei.com>
Signed-off-by: Julia Lawall <Julia.Lawall@inria.fr>
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As other rules done, we add rules for str_write_read()
to check the relative opportunities.
Signed-off-by: Hongbo Li <lihongbo22@huawei.com>
Signed-off-by: Julia Lawall <Julia.Lawall@inria.fr>
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As other rules done, we add rules for str_read_write()
to check the relative opportunities.
Signed-off-by: Hongbo Li <lihongbo22@huawei.com>
Signed-off-by: Julia Lawall <Julia.Lawall@inria.fr>
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As other rules done, we add rules for str_enable{d}_
disable{d}() to check the relative opportunities.
Signed-off-by: Hongbo Li <lihongbo22@huawei.com>
Signed-off-by: Julia Lawall <Julia.Lawall@inria.fr>
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As other rules done, we add rules for str_lo{w}_hi{gh}()
to check the relative opportunities.
Signed-off-by: Hongbo Li <lihongbo22@huawei.com>
Signed-off-by: Julia Lawall <Julia.Lawall@inria.fr>
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As other rules done, we add rules for str_hi{gh}_lo{w}()
to check the relative opportunities.
Signed-off-by: Hongbo Li <lihongbo22@huawei.com>
Signed-off-by: Julia Lawall <Julia.Lawall@inria.fr>
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As done with str_true_false(), add checks for str_false_true()
opportunities. A simple test can find over 9 cases currently
exist in the tree.
Signed-off-by: Hongbo Li <lihongbo22@huawei.com>
Signed-off-by: Julia Lawall <Julia.Lawall@inria.fr>
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After str_true_false() has been introduced in the tree,
we can add rules for finding places where str_true_false()
can be used. A simple test can find over 10 locations.
Signed-off-by: Hongbo Li <lihongbo22@huawei.com>
Signed-off-by: Julia Lawall <Julia.Lawall@inria.fr>
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Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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if an inode backpointer points to a dirent that doesn't point back,
that's an error we should warn about.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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If the reader acquires the read lock and then the writer enters the slow
path, while the reader proceeds to the unlock path, the following scenario
can occur without the change:
writer: pcpu_read_count(lock) return 1 (so __do_six_trylock will return 0)
reader: this_cpu_dec(*lock->readers)
reader: smp_mb()
reader: state = atomic_read(&lock->state) (there is no waiting flag set)
writer: six_set_bitmask()
then the writer will sleep forever.
Signed-off-by: Alan Huang <mmpgouride@gmail.com>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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If we shut down successfully, there shouldn't be any logged ops to
resume.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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Add a filesystem flag to indicate whether we did a clean recovery -
using c->sb.clean after we've got rw is incorrect, since c->sb is
updated whenever we write the superblock.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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We had a bug where disk accounting keys didn't always have their version
field set in journal replay; change the BUG_ON() to a WARN(), and
exclude this case since it's now checked for elsewhere (in the bkey
validate function).
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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This was added to avoid double-counting accounting keys in journal
replay. But applied incorrectly (easily done since it applies to the
transaction commit, not a particular update), it leads to skipping
in-mem accounting for real accounting updates, and failure to give them
a version number - which leads to journal replay becoming very confused
the next time around.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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give bversions a more distinct name, to aid in grepping
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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Previously, check_inode() would delete unlinked inodes if they weren't
on the deleted list - this code dating from before there was a deleted
list.
But, if we crash during a logged op (truncate or finsert/fcollapse) of
an unlinked file, logged op resume will get confused if the inode has
already been deleted - instead, just add it to the deleted list if it
needs to be there; delete_dead_inodes runs after logged op resume.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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BCH_SB_ERRS() has a field for the actual enum val so that we can reorder
to reorganize, but the way BCH_SB_ERR_MAX was defined didn't allow for
this.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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__bch2_fsck_err() warns if the current task has a btree_trans object and
it wasn't passed in, because if it has to prompt for user input it has
to be able to unlock it.
But plumbing the btree_trans through bkey_validate(), as well as
transaction restarts, is problematic - so instead make bkey fsck errors
FSCK_AUTOFIX, which doesn't need to warn.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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In order to check for accounting keys with version=0, we need to run
validation after they've been assigned version numbers.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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Thomas Gleixner
Zhen Lei
Linus Torvalds
Julia Lawall
Hongbo Li
Kent Overstreet
Alan Huang