From owner-svn-src-all@freebsd.org Fri May 26 11:29:32 2017 Return-Path: Delivered-To: svn-src-all@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id A3225D823FA; Fri, 26 May 2017 11:29:32 +0000 (UTC) (envelope-from avg@FreeBSD.org) Received: from repo.freebsd.org (repo.freebsd.org [IPv6:2610:1c1:1:6068::e6a:0]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 5AACB1483; Fri, 26 May 2017 11:29:32 +0000 (UTC) (envelope-from avg@FreeBSD.org) Received: from repo.freebsd.org ([127.0.1.37]) by repo.freebsd.org (8.15.2/8.15.2) with ESMTP id v4QBTVng076156; Fri, 26 May 2017 11:29:31 GMT (envelope-from avg@FreeBSD.org) Received: (from avg@localhost) by repo.freebsd.org (8.15.2/8.15.2/Submit) id v4QBTVl9076155; Fri, 26 May 2017 11:29:31 GMT (envelope-from avg@FreeBSD.org) Message-Id: <201705261129.v4QBTVl9076155@repo.freebsd.org> X-Authentication-Warning: repo.freebsd.org: avg set sender to avg@FreeBSD.org using -f From: Andriy Gapon Date: Fri, 26 May 2017 11:29:31 +0000 (UTC) To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-vendor@freebsd.org Subject: svn commit: r318927 - vendor-sys/illumos/dist/uts/common/fs/zfs X-SVN-Group: vendor-sys MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-BeenThere: svn-src-all@freebsd.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: "SVN commit messages for the entire src tree \(except for " user" and " projects" \)" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 26 May 2017 11:29:32 -0000 Author: avg Date: Fri May 26 11:29:31 2017 New Revision: 318927 URL: https://svnweb.freebsd.org/changeset/base/318927 Log: 8025 dbuf_read() creates unnecessary zio_root() for bonus buf illumos/illumos-gate@def4fac5882b4ca67bd0f4a53509b6d1fa8ae14e https://github.com/illumos/illumos-gate/commit/def4fac5882b4ca67bd0f4a53509b6d1fa8ae14e https://www.illumos.org/issues/8025 dbuf_read() creates a zio_root() to track and wait for all the zio's that may happen as part of this call. However, if the blkptr_t for this buffer is NULL or a hole, we will not create any more zio's, so this zio_root() is unnecessary. This is always the case when calling dbuf_read() on a bonus buffer, because it has no blkptr (it's part of the containing dnode). For workloads that read a lot of bonus buffers (e.g. file creation and removal), creating and destroying these unnecessary zio's can decrease performance by around 3%. Reviewed by: Dan Kimmel Reviewed by: Pavel Zakharov Reviewed by: Prashanth Sreenivasa Approved by: Robert Mustacchi Author: Matthew Ahrens Modified: vendor-sys/illumos/dist/uts/common/fs/zfs/dbuf.c Modified: vendor-sys/illumos/dist/uts/common/fs/zfs/dbuf.c ============================================================================== --- vendor-sys/illumos/dist/uts/common/fs/zfs/dbuf.c Fri May 26 11:25:44 2017 (r318926) +++ vendor-sys/illumos/dist/uts/common/fs/zfs/dbuf.c Fri May 26 11:29:31 2017 (r318927) @@ -1088,7 +1088,6 @@ int dbuf_read(dmu_buf_impl_t *db, zio_t *zio, uint32_t flags) { int err = 0; - boolean_t havepzio = (zio != NULL); boolean_t prefetch; dnode_t *dn; @@ -1132,9 +1131,13 @@ dbuf_read(dmu_buf_impl_t *db, zio_t *zio DB_DNODE_EXIT(db); } else if (db->db_state == DB_UNCACHED) { spa_t *spa = dn->dn_objset->os_spa; + boolean_t need_wait = B_FALSE; - if (zio == NULL) + if (zio == NULL && + db->db_blkptr != NULL && !BP_IS_HOLE(db->db_blkptr)) { zio = zio_root(spa, NULL, NULL, ZIO_FLAG_CANFAIL); + need_wait = B_TRUE; + } dbuf_read_impl(db, zio, flags); /* dbuf_read_impl has dropped db_mtx for us */ @@ -1146,7 +1149,7 @@ dbuf_read(dmu_buf_impl_t *db, zio_t *zio rw_exit(&dn->dn_struct_rwlock); DB_DNODE_EXIT(db); - if (!havepzio) + if (need_wait) err = zio_wait(zio); } else { /* @@ -1181,7 +1184,6 @@ dbuf_read(dmu_buf_impl_t *db, zio_t *zio mutex_exit(&db->db_mtx); } - ASSERT(err || havepzio || db->db_state == DB_CACHED); return (err); }