Optimize spl_kmem_cache_free()

Because only virtual slabs may have emergency objects and these
objects are guaranteed to have physical addresses.  It can be
easily determined if the passed object is a virtual slab object
or an emergency object.  This allows us to completely optimize
the emergency object free case out of the common free path.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>

diff --git a/module/spl/spl-kmem.c b/module/spl/spl-kmem.c
index 7e68522ad3ea87370a9ac2146162cbcb77b4b2ee..5627b5590be8eb22f46df4a24610b19946e02d91 100644 (file)
--- a/module/spl/spl-kmem.c
+++ b/module/spl/spl-kmem.c
@@ -2023,11 +2023,12 @@ spl_kmem_cache_free(spl_kmem_cache_t *skc, void *obj)
        atomic_inc(&skc->skc_ref);
 
        /*
-        * Emergency objects are never part of the virtual address space
-        * so if we get a virtual address we can optimize this check out.
+        * Only virtual slabs may have emergency objects and these objects
+        * are guaranteed to have physical addresses.  They must be removed
+        * from the tree of emergency objects and the freed.
         */
-       if (!kmem_virt(obj) && !spl_emergency_free(skc, obj))
-               SGOTO(out, 0);
+       if ((skc->skc_flags & KMC_VMEM) && !kmem_virt(obj))
+               SGOTO(out, spl_emergency_free(skc, obj));
 
        local_irq_save(flags);