From owner-svn-src-all@freebsd.org Mon Oct 19 09:52:53 2020 Return-Path: Delivered-To: svn-src-all@mailman.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.nyi.freebsd.org (Postfix) with ESMTP id 496AF44AE9C; Mon, 19 Oct 2020 09:52:53 +0000 (UTC) (envelope-from mjg@FreeBSD.org) Received: from mxrelay.nyi.freebsd.org (mxrelay.nyi.freebsd.org [IPv6:2610:1c1:1:606c::19:3]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256 client-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "mxrelay.nyi.freebsd.org", Issuer "Let's Encrypt Authority X3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 4CFBrj1Fx7z4N8w; Mon, 19 Oct 2020 09:52:53 +0000 (UTC) (envelope-from mjg@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 mxrelay.nyi.freebsd.org (Postfix) with ESMTPS id 0E79221D19; Mon, 19 Oct 2020 09:52:53 +0000 (UTC) (envelope-from mjg@FreeBSD.org) Received: from repo.freebsd.org ([127.0.1.37]) by repo.freebsd.org (8.15.2/8.15.2) with ESMTP id 09J9qqrD083268; Mon, 19 Oct 2020 09:52:52 GMT (envelope-from mjg@FreeBSD.org) Received: (from mjg@localhost) by repo.freebsd.org (8.15.2/8.15.2/Submit) id 09J9qqFi083267; Mon, 19 Oct 2020 09:52:52 GMT (envelope-from mjg@FreeBSD.org) Message-Id: <202010190952.09J9qqFi083267@repo.freebsd.org> X-Authentication-Warning: repo.freebsd.org: mjg set sender to mjg@FreeBSD.org using -f From: Mateusz Guzik Date: Mon, 19 Oct 2020 09:52:52 +0000 (UTC) To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r366829 - head/sys/kern X-SVN-Group: head X-SVN-Commit-Author: mjg X-SVN-Commit-Paths: head/sys/kern X-SVN-Commit-Revision: 366829 X-SVN-Commit-Repository: base 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: 2.1.33 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: Mon, 19 Oct 2020 09:52:53 -0000 Author: mjg Date: Mon Oct 19 09:52:52 2020 New Revision: 366829 URL: https://svnweb.freebsd.org/changeset/base/366829 Log: cache: refactor negative promotion/demotion handling This will simplify policy changes. Modified: head/sys/kern/vfs_cache.c Modified: head/sys/kern/vfs_cache.c ============================================================================== --- head/sys/kern/vfs_cache.c Mon Oct 19 07:26:42 2020 (r366828) +++ head/sys/kern/vfs_cache.c Mon Oct 19 09:52:52 2020 (r366829) @@ -908,11 +908,37 @@ cache_neg_init(struct namecache *ncp) counter_u64_add(neg_created, 1); } +static bool +cache_neg_hit_prep(struct namecache *ncp) +{ + struct negstate *ns; + + ns = NCP2NEGSTATE(ncp); + if ((ns->neg_flag & NEG_HOT) != 0) + return (true); + return (false); +} + /* + * Nothing to do here but it is provided for completeness as some + * cache_neg_hit_prep callers may end up returning without even + * trying to promote. + */ +#define cache_neg_hit_abort(ncp) do { } while (0) + +static void +cache_neg_hit_finish(struct namecache *ncp) +{ + + SDT_PROBE2(vfs, namecache, lookup, hit__negative, ncp->nc_dvp, ncp->nc_name); + counter_u64_add(numneghits, 1); +} + +/* * Move a negative entry to the hot list. */ static void -cache_neg_promote(struct namecache *ncp) +cache_neg_promote_locked(struct namecache *ncp) { struct neglist *nl; struct negstate *ns; @@ -929,6 +955,25 @@ cache_neg_promote(struct namecache *ncp) } /* + * Move a hot negative entry to the cold list. + */ +static void +cache_neg_demote_locked(struct namecache *ncp) +{ + struct neglist *nl; + struct negstate *ns; + + ns = NCP2NEGSTATE(ncp); + nl = NCP2NEGLIST(ncp); + mtx_assert(&nl->nl_lock, MA_OWNED); + MPASS(ns->neg_flag & NEG_HOT); + TAILQ_REMOVE(&nl->nl_hotlist, ncp, nc_dst); + TAILQ_INSERT_TAIL(&nl->nl_list, ncp, nc_dst); + nl->nl_hotnum--; + ns->neg_flag &= ~NEG_HOT; +} + +/* * Move a negative entry to the hot list if it matches the lookup. * * We have to take locks, but they may be contended and in the worst @@ -996,10 +1041,8 @@ cache_neg_promote_cond(struct vnode *dvp, struct compo goto out_abort; } - cache_neg_promote(ncp); - - SDT_PROBE2(vfs, namecache, lookup, hit__negative, dvp, ncp->nc_name); - counter_u64_add(numneghits, 1); + cache_neg_promote_locked(ncp); + cache_neg_hit_finish(ncp); vfs_smr_exit(); mtx_unlock(&nl->nl_lock); return (true); @@ -1010,17 +1053,13 @@ out_abort: } static void -cache_neg_hit(struct namecache *ncp) +cache_neg_promote(struct namecache *ncp) { struct neglist *nl; - struct negstate *ns; - ns = NCP2NEGSTATE(ncp); - if ((ns->neg_flag & NEG_HOT) != 0) - return; nl = NCP2NEGLIST(ncp); mtx_lock(&nl->nl_lock); - cache_neg_promote(ncp); + cache_neg_promote_locked(ncp); mtx_unlock(&nl->nl_lock); } @@ -1094,11 +1133,7 @@ cache_neg_evict(void) mtx_lock(&nl->nl_lock); ncp = TAILQ_FIRST(&nl->nl_hotlist); if (ncp != NULL) { - ns = NCP2NEGSTATE(ncp); - TAILQ_REMOVE(&nl->nl_hotlist, ncp, nc_dst); - TAILQ_INSERT_TAIL(&nl->nl_list, ncp, nc_dst); - nl->nl_hotnum--; - ns->neg_flag &= ~NEG_HOT; + cache_neg_demote_locked(ncp); } ncp = TAILQ_FIRST(&nl->nl_list); if (ncp == NULL) { @@ -1542,11 +1577,12 @@ negative_success: } } - SDT_PROBE2(vfs, namecache, lookup, hit__negative, dvp, ncp->nc_name); - cache_out_ts(ncp, tsp, ticksp); - counter_u64_add(numneghits, 1); whiteout = (ncp->nc_flag & NCF_WHITE); - cache_neg_hit(ncp); + cache_out_ts(ncp, tsp, ticksp); + if (cache_neg_hit_prep(ncp)) + cache_neg_promote(ncp); + else + cache_neg_hit_finish(ncp); mtx_unlock(dvlp); if (whiteout) cnp->cn_flags |= ISWHITEOUT; @@ -1653,11 +1689,12 @@ negative_success: } } - SDT_PROBE2(vfs, namecache, lookup, hit__negative, dvp, ncp->nc_name); - cache_out_ts(ncp, tsp, ticksp); - counter_u64_add(numneghits, 1); whiteout = (ncp->nc_flag & NCF_WHITE); - cache_neg_hit(ncp); + cache_out_ts(ncp, tsp, ticksp); + if (cache_neg_hit_prep(ncp)) + cache_neg_promote(ncp); + else + cache_neg_hit_finish(ncp); mtx_unlock(blp); if (whiteout) cnp->cn_flags |= ISWHITEOUT; @@ -1669,11 +1706,10 @@ cache_lookup(struct vnode *dvp, struct vnode **vpp, st struct timespec *tsp, int *ticksp) { struct namecache *ncp; - struct negstate *ns; uint32_t hash; enum vgetstate vs; int error; - bool whiteout, neg_hot; + bool whiteout, neg_promote; u_short nc_flag; MPASS((tsp == NULL && ticksp == NULL) || (tsp != NULL && ticksp != NULL)); @@ -1752,19 +1788,18 @@ negative_success: cache_out_ts(ncp, tsp, ticksp); whiteout = (ncp->nc_flag & NCF_WHITE); - ns = NCP2NEGSTATE(ncp); - neg_hot = ((ns->neg_flag & NEG_HOT) != 0); + neg_promote = cache_neg_hit_prep(ncp); if (__predict_false(!cache_ncp_canuse(ncp))) { + cache_neg_hit_abort(ncp); vfs_smr_exit(); goto out_fallback; } - if (!neg_hot) { + if (neg_promote) { vfs_smr_exit(); if (!cache_neg_promote_cond(dvp, cnp, ncp, hash)) goto out_fallback; } else { - SDT_PROBE2(vfs, namecache, lookup, hit__negative, dvp, ncp->nc_name); - counter_u64_add(numneghits, 1); + cache_neg_hit_finish(ncp); vfs_smr_exit(); } if (whiteout) @@ -3917,12 +3952,9 @@ cache_fplookup_dotdot(struct cache_fpl *fpl) static int __noinline cache_fplookup_neg(struct cache_fpl *fpl, struct namecache *ncp, uint32_t hash) { - struct negstate *ns; - struct vnode *dvp; u_char nc_flag; - bool neg_hot; + bool neg_promote; - dvp = fpl->dvp; nc_flag = atomic_load_char(&ncp->nc_flag); MPASS((nc_flag & NCF_NEGATIVE) != 0); /* @@ -3936,19 +3968,19 @@ cache_fplookup_neg(struct cache_fpl *fpl, struct namec */ return (cache_fpl_partial(fpl)); } - ns = NCP2NEGSTATE(ncp); - neg_hot = ((ns->neg_flag & NEG_HOT) != 0); + neg_promote = cache_neg_hit_prep(ncp); if (__predict_false(!cache_ncp_canuse(ncp))) { + cache_neg_hit_abort(ncp); return (cache_fpl_partial(fpl)); } if (__predict_false((nc_flag & NCF_WHITE) != 0)) { + cache_neg_hit_abort(ncp); return (cache_fpl_partial(fpl)); } - if (!neg_hot) { + if (neg_promote) { return (cache_fplookup_negative_promote(fpl, ncp, hash)); } - SDT_PROBE2(vfs, namecache, lookup, hit__negative, dvp, ncp->nc_name); - counter_u64_add(numneghits, 1); + cache_neg_hit_finish(ncp); cache_fpl_smr_exit(fpl); return (cache_fpl_handled(fpl, ENOENT)); }