Linux 2.6.29 compat, credentials

[zfs.git] / module / zfs / arc.c

diff --git a/module/zfs/arc.c b/module/zfs/arc.c
index 63b659b..9ca8ad1 100644 (file)
--- a/module/zfs/arc.c
+++ b/module/zfs/arc.c
@@ -282,6 +282,8 @@ typedef struct arc_stats {
        kstat_named_t arcstat_l2_size;
        kstat_named_t arcstat_l2_hdr_size;
        kstat_named_t arcstat_memory_throttle_count;
+       kstat_named_t arcstat_memory_direct_count;
+       kstat_named_t arcstat_memory_indirect_count;
        kstat_named_t arcstat_no_grow;
        kstat_named_t arcstat_tempreserve;
        kstat_named_t arcstat_loaned_bytes;
@@ -344,6 +346,8 @@ static arc_stats_t arc_stats = {
        { "l2_size",                    KSTAT_DATA_UINT64 },
        { "l2_hdr_size",                KSTAT_DATA_UINT64 },
        { "memory_throttle_count",      KSTAT_DATA_UINT64 },
+       { "memory_direct_count",        KSTAT_DATA_UINT64 },
+       { "memory_indirect_count",      KSTAT_DATA_UINT64 },
        { "arc_no_grow",                KSTAT_DATA_UINT64 },
        { "arc_tempreserve",            KSTAT_DATA_UINT64 },
        { "arc_loaned_bytes",           KSTAT_DATA_UINT64 },
@@ -2171,6 +2175,51 @@ arc_reclaim_thread(void)
        thread_exit();
 }
 
+#ifdef _KERNEL
+/*
+ * Under Linux the arc shrinker may be called for synchronous (direct)
+ * reclaim, or asynchronous (indirect) reclaim.  When called by kswapd
+ * for indirect reclaim we take a conservative approach and just reap
+ * free slabs from the ARC caches.  If this proves to be insufficient
+ * direct reclaim will be trigger.  In direct reclaim a more aggressive
+ * strategy is used, data is evicted from the ARC and free slabs reaped.
+ */
+SPL_SHRINKER_CALLBACK_PROTO(arc_shrinker_func, cb, nr_to_scan, gfp_mask)
+{
+       arc_reclaim_strategy_t strategy;
+       int arc_reclaim;
+
+       /* Not allowed to perform filesystem reclaim */
+       if (!(gfp_mask & __GFP_FS))
+               return (-1);
+
+       /* Return number of reclaimable pages based on arc_shrink_shift */
+       arc_reclaim = btop((arc_size - arc_c_min)) >> arc_shrink_shift;
+       if (nr_to_scan == 0)
+               return (arc_reclaim);
+
+       /* Reclaim in progress */
+       if (mutex_tryenter(&arc_reclaim_thr_lock) == 0)
+               return (-1);
+
+       if (current_is_kswapd()) {
+               strategy = ARC_RECLAIM_CONS;
+               ARCSTAT_INCR(arcstat_memory_indirect_count, 1);
+       } else {
+               strategy = ARC_RECLAIM_AGGR;
+               ARCSTAT_INCR(arcstat_memory_direct_count, 1);
+       }
+
+       arc_kmem_reap_now(strategy);
+       arc_reclaim = btop((arc_size - arc_c_min)) >> arc_shrink_shift;
+       mutex_exit(&arc_reclaim_thr_lock);
+
+       return (arc_reclaim);
+}
+
+SPL_SHRINKER_DECLARE(arc_shrinker, arc_shrinker_func, DEFAULT_SEEKS);
+#endif /* _KERNEL */
+
 /*
  * Adapt arc info given the number of bytes we are trying to add and
  * the state that we are comming from.  This function is only called
@@ -3485,6 +3534,12 @@ arc_init(void)
         * need to limit the cache to 1/8 of VM size.
         */
        arc_c = MIN(arc_c, vmem_size(heap_arena, VMEM_ALLOC | VMEM_FREE) / 8);
+       /*
+        * Register a shrinker to support synchronous (direct) memory
+        * reclaim from the arc.  This is done to prevent kswapd from
+        * swapping out pages when it is preferable to shrink the arc.
+        */
+       spl_register_shrinker(&arc_shrinker);
 #endif
 
        /* set min cache to 1/32 of all memory, or 64MB, whichever is more */
@@ -3602,6 +3657,10 @@ void
 arc_fini(void)
 {
        mutex_enter(&arc_reclaim_thr_lock);
+#ifdef _KERNEL
+       spl_unregister_shrinker(&arc_shrinker);
+#endif /* _KERNEL */
+
        arc_thread_exit = 1;
        while (arc_thread_exit != 0)
                cv_wait(&arc_reclaim_thr_cv, &arc_reclaim_thr_lock);