svn commit: r325609 - in vendor-sys/illumos/dist/uts/common/fs/zfs: . sys

[Andriy Gapon]

Author: avg
Date: Thu Nov  9 18:21:17 2017
New Revision: 325609
URL: https://svnweb.freebsd.org/changeset/base/325609

Log:
  7531 Assign correct flags to prefetched buffers
  
  illumos/illumos-gate at 272952165423c254ad7708f1b3fe2ff0a6ce408b
  https://github.com/illumos/illumos-gate/commit/272952165423c254ad7708f1b3fe2ff0a6ce408b
  
  https://www.illumos.org/issues/7531
    I found that some buffers that could be L2ARC eligible are not flagged
    such, leading to some performance impact.  As a test I ran the same IO
    workload 10 times in a raw.  It is a metadata only workload (files
    listing).  l2arc_noprefetch=0.
  
  Reviewed by: Matthew Ahrens <mahrens at delphix.com>
  Reviewed by: Prakash Surya <prakash.surya at delphix.com>
  Approved by: Dan McDonald <danmcd at joyent.com>
  Author: benrubson <ben.rubson at gmail.com>
  
  MFC after:	8 days

Modified:
  vendor-sys/illumos/dist/uts/common/fs/zfs/dbuf.c
  vendor-sys/illumos/dist/uts/common/fs/zfs/sys/dbuf.h

Modified: vendor-sys/illumos/dist/uts/common/fs/zfs/dbuf.c
==============================================================================
--- vendor-sys/illumos/dist/uts/common/fs/zfs/dbuf.c	Thu Nov  9 18:14:42 2017	(r325608)
+++ vendor-sys/illumos/dist/uts/common/fs/zfs/dbuf.c	Thu Nov  9 18:21:17 2017	(r325609)
@@ -2374,6 +2374,10 @@ dbuf_prefetch_indirect_done(zio_t *zio, arc_buf_t *abu
 		arc_flags_t iter_aflags = ARC_FLAG_NOWAIT;
 		zbookmark_phys_t zb;
 
+		/* flag if L2ARC eligible, l2arc_noprefetch then decides */
+		if (dpa->dpa_aflags & ARC_FLAG_L2CACHE)
+			iter_aflags |= ARC_FLAG_L2CACHE;
+
 		ASSERT3U(dpa->dpa_curlevel, ==, BP_GET_LEVEL(bp));
 
 		SET_BOOKMARK(&zb, dpa->dpa_zb.zb_objset,
@@ -2483,6 +2487,10 @@ dbuf_prefetch(dnode_t *dn, int64_t level, uint64_t blk
 	dpa->dpa_epbs = epbs;
 	dpa->dpa_zio = pio;
 
+	/* flag if L2ARC eligible, l2arc_noprefetch then decides */
+	if (DNODE_LEVEL_IS_L2CACHEABLE(dn, level))
+		dpa->dpa_aflags |= ARC_FLAG_L2CACHE;
+
 	/*
 	 * If we have the indirect just above us, no need to do the asynchronous
 	 * prefetch chain; we'll just run the last step ourselves.  If we're at
@@ -2497,6 +2505,10 @@ dbuf_prefetch(dnode_t *dn, int64_t level, uint64_t blk
 	} else {
 		arc_flags_t iter_aflags = ARC_FLAG_NOWAIT;
 		zbookmark_phys_t zb;
+
+		/* flag if L2ARC eligible, l2arc_noprefetch then decides */
+		if (DNODE_LEVEL_IS_L2CACHEABLE(dn, level))
+			iter_aflags |= ARC_FLAG_L2CACHE;
 
 		SET_BOOKMARK(&zb, ds != NULL ? ds->ds_object : DMU_META_OBJSET,
 		    dn->dn_object, curlevel, curblkid);

Modified: vendor-sys/illumos/dist/uts/common/fs/zfs/sys/dbuf.h
==============================================================================
--- vendor-sys/illumos/dist/uts/common/fs/zfs/sys/dbuf.h	Thu Nov  9 18:14:42 2017	(r325608)
+++ vendor-sys/illumos/dist/uts/common/fs/zfs/sys/dbuf.h	Thu Nov  9 18:21:17 2017	(r325609)
@@ -347,6 +347,12 @@ boolean_t dbuf_is_metadata(dmu_buf_impl_t *db);
 	(dbuf_is_metadata(_db) &&					\
 	((_db)->db_objset->os_secondary_cache == ZFS_CACHE_METADATA)))
 
+#define	DNODE_LEVEL_IS_L2CACHEABLE(_dn, _level)				\
+	((_dn)->dn_objset->os_secondary_cache == ZFS_CACHE_ALL ||	\
+	(((_level) > 0 ||						\
+	DMU_OT_IS_METADATA((_dn)->dn_handle->dnh_dnode->dn_type)) &&	\
+	((_dn)->dn_objset->os_secondary_cache == ZFS_CACHE_METADATA)))
+
 #ifdef ZFS_DEBUG
 
 /*