diff options
| author | Brian Behlendorf <[email protected]> | 2012-10-29 16:51:59 -0700 |
|---|---|---|
| committer | Brian Behlendorf <[email protected]> | 2012-11-06 14:54:15 -0800 |
| commit | 165f13c33abadc06ccaea1c4f654fddfa316a80f (patch) | |
| tree | 167c1501a7d45df8e879256ffbf2204ba241d83f /include | |
| parent | 65c2fc5a2ed3a60711cc63e53b3ab01e9d5095ae (diff) | |
Improved vmem cached deadlock detection
The entire goal of performing the slab allocations asynchronously
is to be able to detect when a vmalloc() deadlocks. In this case,
and only this case, do we want to start allocating emergency objects.
The trick here is to minimize false positives because the overhead
of tracking emergency objects is far higher than normal slab objects.
With that goal in mind the code was reworked to be less sensitive
to slow allocations by increasing the wait time. Once a cache is
is marked deadlocked all subsequent allocations which can not be
satisfied with existing cache objects will immediately allocate new
emergency objects. This behavior persists until the asynchronous
allocation completes and clears the deadlocked flag.
The result of these tweaks is that far fewer emergency objects
get created which is important because this minimizes the cost of
releasing them latter in kmem_cache_free().
Signed-off-by: Brian Behlendorf <[email protected]>
Diffstat (limited to 'include')
| -rw-r--r-- | include/sys/kmem.h | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/include/sys/kmem.h b/include/sys/kmem.h index e71a443a0..b0f4208bd 100644 --- a/include/sys/kmem.h +++ b/include/sys/kmem.h @@ -340,6 +340,7 @@ enum { KMC_BIT_VMEM = 6, /* Use vmem cache */ KMC_BIT_OFFSLAB = 7, /* Objects not on slab */ KMC_BIT_NOEMERGENCY = 8, /* Disable emergency objects */ + KMC_BIT_DEADLOCKED = 14, /* Deadlock detected */ KMC_BIT_GROWING = 15, /* Growing in progress */ KMC_BIT_REAPING = 16, /* Reaping in progress */ KMC_BIT_DESTROY = 17, /* Destroy in progress */ @@ -366,6 +367,7 @@ typedef enum kmem_cbrc { #define KMC_VMEM (1 << KMC_BIT_VMEM) #define KMC_OFFSLAB (1 << KMC_BIT_OFFSLAB) #define KMC_NOEMERGENCY (1 << KMC_BIT_NOEMERGENCY) +#define KMC_DEADLOCKED (1 << KMC_BIT_DEADLOCKED) #define KMC_GROWING (1 << KMC_BIT_GROWING) #define KMC_REAPING (1 << KMC_BIT_REAPING) #define KMC_DESTROY (1 << KMC_BIT_DESTROY) @@ -473,6 +475,7 @@ typedef struct spl_kmem_cache { uint64_t skc_obj_total; /* Obj total current */ uint64_t skc_obj_alloc; /* Obj alloc current */ uint64_t skc_obj_max; /* Obj max historic */ + uint64_t skc_obj_deadlock; /* Obj emergency deadlocks */ uint64_t skc_obj_emergency; /* Obj emergency current */ uint64_t skc_obj_emergency_max; /* Obj emergency max */ } spl_kmem_cache_t; |