svn commit: r367360 - head/sys/contrib/openzfs/module/zfs

[Mateusz Guzik]

Author: mjg
Date: Thu Nov  5 03:25:23 2020
New Revision: 367360
URL: https://svnweb.freebsd.org/changeset/base/367360

Log:
  zfs: lz4: add optional kmem_alloc support
  
  lz4 port from illumos to Linux added a 16KB per-CPU cache to accommodate for
  the missing 16KB malloc. FreeBSD supports this size, making the extra cache
  harmful as it can't share buckets.

Modified:
  head/sys/contrib/openzfs/module/zfs/lz4.c

Modified: head/sys/contrib/openzfs/module/zfs/lz4.c
==============================================================================
--- head/sys/contrib/openzfs/module/zfs/lz4.c	Thu Nov  5 02:57:40 2020	(r367359)
+++ head/sys/contrib/openzfs/module/zfs/lz4.c	Thu Nov  5 03:25:23 2020	(r367360)
@@ -44,7 +44,8 @@ static int LZ4_compressCtx(void *ctx, const char *sour
 static int LZ4_compress64kCtx(void *ctx, const char *source, char *dest,
     int isize, int osize);
 
-static kmem_cache_t *lz4_cache;
+static void *lz4_alloc(int flags);
+static void lz4_free(void *ctx);
 
 /*ARGSUSED*/
 size_t
@@ -838,8 +839,7 @@ real_LZ4_compress(const char *source, char *dest, int 
 	void *ctx;
 	int result;
 
-	ASSERT(lz4_cache != NULL);
-	ctx = kmem_cache_alloc(lz4_cache, KM_SLEEP);
+	ctx = lz4_alloc(KM_SLEEP);
 
 	/*
 	 * out of kernel memory, gently fall through - this will disable
@@ -855,7 +855,7 @@ real_LZ4_compress(const char *source, char *dest, int 
 	else
 		result = LZ4_compressCtx(ctx, source, dest, isize, osize);
 
-	kmem_cache_free(lz4_cache, ctx);
+	lz4_free(ctx);
 	return (result);
 }
 
@@ -1014,6 +1014,23 @@ LZ4_uncompress_unknownOutputSize(const char *source, c
 	return (-1);
 }
 
+#ifdef __FreeBSD__
+/*
+ * FreeBSD has 4, 8 and 16 KB malloc zones which can be used here.
+ * Should struct refTables get resized this may need to be revisited, hence
+ * compiler-time asserts.
+ */
+_Static_assert(sizeof(struct refTables) <= 16384,
+    "refTables too big for malloc");
+_Static_assert((sizeof(struct refTables) % 4096) == 0,
+    "refTables not a multiple of page size");
+#else
+#define ZFS_LZ4_USE_CACHE
+#endif
+
+#ifdef ZFS_LZ4_USE_CACHE
+static kmem_cache_t *lz4_cache;
+
 void
 lz4_init(void)
 {
@@ -1029,3 +1046,39 @@ lz4_fini(void)
 		lz4_cache = NULL;
 	}
 }
+
+static void *
+lz4_alloc(int flags)
+{
+	ASSERT(lz4_cache != NULL);
+	return (kmem_cache_alloc(lz4_cache, flags));
+}
+
+static void
+lz4_free(void *ctx)
+{
+	kmem_cache_free(lz4_cache, ctx);
+}
+#else
+void
+lz4_init(void)
+{
+}
+
+void
+lz4_fini(void)
+{
+}
+
+static void *
+lz4_alloc(int flags)
+{
+	return (kmem_alloc(sizeof (struct refTables), flags));
+}
+
+static void
+lz4_free(void *ctx)
+{
+	kmem_free(ctx, sizeof (struct refTables));
+}
+#endif