class Evictor
Defined at line 36 of file ../../zircon/kernel/vm/include/vm/evictor.h
Implements page evictor logic to free pages belonging to a PmmNode under memory pressure.
Eviction in this context is both direct eviction of pager backed memory and discardable VMO
memory, as well as by performing compression.
This class is thread-safe.
Public Methods
void Evictor ()Defined at line 40 of file ../../zircon/kernel/vm/evictor.cc
void ~Evictor ()Defined at line 47 of file ../../zircon/kernel/vm/evictor.cc
void EnableEviction (bool use_compression)Called from the scanner to enable eviction if required. Creates an eviction thread to process
asynchronous eviction requests.
By default this only enables user pager based eviction and |use_compression| can be used to
also perform compression.
Defined at line 49 of file ../../zircon/kernel/vm/evictor.cc
void DisableEviction ()Called from the scanner to disable all eviction if needed, will shut down any in existing
eviction thread. It is a responsibility of the scanner to not have multiple concurrent calls
to this and EnableEviction.
Defined at line 53 of file ../../zircon/kernel/vm/evictor.cc
EvictionResult EvictFromExternalTarget (EvictionTarget target)Evict from a user specified external |target| which is only used for this eviction attempt and
does not interfere with the |eviction_target_|.
Defined at line 55 of file ../../zircon/kernel/vm/evictor.cc
EvictionResult EvictSynchronous (uint64_tmin_mem_to_free,uint64_tfree_mem_target,EvictionLeveleviction_level,Outputoutput,TriggerReasonreason)
Performs a synchronous request to evict until free memory equals |free_mem_start| (in bytes)
and at least |min_mem_to_free| (in bytes) has been reclaimed. The return value is an
EvictionResult detailing exactly what was evicted and whether the free_mem_target was achieved.
The |eviction_level| is a rough control that maps to how old a page needs to be for being
considered for eviction. This may acquire arbitrary vmo and aspace locks.
Defined at line 61 of file ../../zircon/kernel/vm/evictor.cc
void EvictAsynchronous (uint64_tmin_mem_to_free,uint64_tfree_mem_target,EvictionLeveleviction_level,Outputoutput)
Reclaim memory until free memory equals the |free_mem_target| (in bytes) and at least
|min_mem_to_free| (in bytes) has been reclaimed. Reclamation will happen asynchronously on the
eviction thread and this function returns immediately. Once the target is reached, or there is
no more memory that can be reclaimed, this process will stop and the free memory target will be
cleared. The |eviction_level| is a rough control on how hard to try and evict. Multiple calls
to EvictAsynchronous will cause all the targets to get merged by adding together
|min_mem_to_free|, taking the max of |free_mem_target| and the highest or most aggressive of
any |eviction_level|.
Defined at line 71 of file ../../zircon/kernel/vm/evictor.cc
bool IsEvictionEnabled ()Whether any eviction can occur.
Defined at line 76 of file ../../zircon/kernel/vm/evictor.cc
bool IsCompressionEnabled ()Whether eviction should attempt to use compression.
Defined at line 78 of file ../../zircon/kernel/vm/evictor.cc
EvictorStats GetGlobalStats ()Return global eviction stats from all instantiations of the Evictor.
Defined at line 81 of file ../../zircon/kernel/vm/evictor.cc
Thread * DebugGetEvictorThread ()Debug method to retrieve any current eviction thread. Only to be used for testing / debugging
purposes. It is up to the caller to know if this objects is alive or not.
Defined at line 87 of file ../../zircon/kernel/vm/evictor.cc
void Evictor (void *ctx,TestReclaimFunctionreclaim_function,TestFreePagesFunctionfree_pages_function)
Constructor for test code to specify custom methods to fake the reclamation.
Defined at line 42 of file ../../zircon/kernel/vm/evictor.cc
EvictionTarget DebugGetEvictionTarget ()Helpers for testing.
Defined at line 89 of file ../../zircon/kernel/vm/evictor.cc
void CombineEvictionTarget (EvictionTarget target)Combine the specified |target| with the pre-existing |eviction_target_|.
Defined at line 95 of file ../../zircon/kernel/vm/evictor.cc
EvictedPageCounts EvictFromPreloadedTarget ()Perform eviction based on the current values of |eviction_target_|. The expectation is that the
user will have set the target before calling this function with either SetEvictionTarget() or
CombineEvictionTarget(). This may acquire arbitrary vmo and aspace locks.
Defined at line 99 of file ../../zircon/kernel/vm/evictor.cc
Enumerations
enum class EvictionLevel : uint8_t| Name | Value |
|---|---|
| OnlyOldest | 0 |
| IncludeNewest | 1 |
Defined at line 38 of file ../../zircon/kernel/vm/include/vm/evictor.h
enum class Output : _Bool| Name | Value |
|---|---|
| true | |
| NoPrint | false |
Defined at line 43 of file ../../zircon/kernel/vm/include/vm/evictor.h
enum class TriggerReason : _Bool| Name | Value |
|---|---|
| OOM | true |
| Other | false |
Defined at line 48 of file ../../zircon/kernel/vm/include/vm/evictor.h