Linux: Reclaim unused spl_kmem_cache_reclaim

It is unused for 3 years since #10576.

Reviewed-by: George Melikov <[email protected]>
Reviewed-by: Brian Behlendorf <[email protected]>
Signed-off-by:	Alexander Motin <[email protected]>
Sponsored by:	iXsystems, Inc.
Closes #15507

Author: amotin

include/os/linux/spl/sys/kmem_cache.h

@@ -70,8 +70,6 @@ typedef enum kmem_cbrc {
 #define	KMC_REAP_CHUNK		INT_MAX
 #define	KMC_DEFAULT_SEEKS	1
 
-#define	KMC_RECLAIM_ONCE	0x1	/* Force a single shrinker pass */
-
 extern struct list_head spl_kmem_cache_list;
 extern struct rw_semaphore spl_kmem_cache_sem;
 

man/man4/spl.4

@@ -31,14 +31,6 @@ for use by the kmem caches.
 For the majority of systems and workloads only a small number of threads are
 required.
 .
-.It Sy spl_kmem_cache_reclaim Ns = Ns Sy 0 Pq uint
-When this is set it prevents Linux from being able to rapidly reclaim all the
-memory held by the kmem caches.
-This may be useful in circumstances where it's preferable that Linux
-reclaim memory from some other subsystem first.
-Setting this will increase the likelihood out of memory events on a memory
-constrained system.
-.
 .It Sy spl_kmem_cache_obj_per_slab Ns = Ns Sy 8 Pq uint
 The preferred number of objects per slab in the cache.
 In general, a larger value will increase the caches memory footprint

module/os/linux/spl/spl-kmem-cache.c

@@ -76,17 +76,6 @@ module_param(spl_kmem_cache_magazine_size, uint, 0444);
 MODULE_PARM_DESC(spl_kmem_cache_magazine_size,
 	"Default magazine size (2-256), set automatically (0)");
 
-/*
- * The default behavior is to report the number of objects remaining in the
- * cache.  This allows the Linux VM to repeatedly reclaim objects from the
- * cache when memory is low satisfy other memory allocations.  Alternately,
- * setting this value to KMC_RECLAIM_ONCE limits how aggressively the cache
- * is reclaimed.  This may increase the likelihood of out of memory events.
- */
-static unsigned int spl_kmem_cache_reclaim = 0 /* KMC_RECLAIM_ONCE */;
-module_param(spl_kmem_cache_reclaim, uint, 0644);
-MODULE_PARM_DESC(spl_kmem_cache_reclaim, "Single reclaim pass (0x1)");
-
 static unsigned int spl_kmem_cache_obj_per_slab = SPL_KMEM_CACHE_OBJ_PER_SLAB;
 module_param(spl_kmem_cache_obj_per_slab, uint, 0644);
 MODULE_PARM_DESC(spl_kmem_cache_obj_per_slab, "Number of objects per slab");