From 83709dfafba5b8b58670cec4a2e95204ef63e6e2 Mon Sep 17 00:00:00 2001 From: Jarno Rajahalme Date: Thu, 24 Apr 2014 08:21:49 -0700 Subject: [PATCH] ofproto: Reduce taking rule references. Only take reference to a looked up rule when needed. This reduces the total CPU utilization of rule_ref/unref calls by 80%, from 5% of total server CPU capacity to 1% in a netperf TCP_CRR test stressing the userspace. Signed-off-by: Jarno Rajahalme Acked-by: Ethan Jackson --- ofproto/ofproto-dpif-xlate.c | 49 ++++++++++++++++++++---------------- 1 file changed, 27 insertions(+), 22 deletions(-) diff --git a/ofproto/ofproto-dpif-xlate.c b/ofproto/ofproto-dpif-xlate.c index c62424a37..6a56a1556 100644 --- a/ofproto/ofproto-dpif-xlate.c +++ b/ofproto/ofproto-dpif-xlate.c @@ -1996,13 +1996,6 @@ xlate_recursively(struct xlate_ctx *ctx, struct rule_dpif *rule) if (ctx->xin->resubmit_stats) { rule_dpif_credit_stats(rule, ctx->xin->resubmit_stats); } - if (ctx->xin->xcache) { - struct xc_entry *entry; - - entry = xlate_cache_add_entry(ctx->xin->xcache, XC_RULE); - entry->u.rule = rule; - rule_dpif_ref(rule); - } ctx->resubmits++; ctx->recurse++; @@ -2057,7 +2050,8 @@ xlate_table_action(struct xlate_ctx *ctx, ofp_port_t in_port, uint8_t table_id, !skip_wildcards ? &ctx->xout->wc : NULL, honor_table_miss, - &ctx->table_id, &rule, true); + &ctx->table_id, &rule, + ctx->xin->xcache != NULL); ctx->xin->flow.in_port.ofp_port = old_in_port; if (ctx->xin->resubmit_hook) { @@ -2090,12 +2084,22 @@ xlate_table_action(struct xlate_ctx *ctx, ofp_port_t in_port, uint8_t table_id, } choose_miss_rule(config, ctx->xbridge->miss_rule, - ctx->xbridge->no_packet_in_rule, &rule, true); + ctx->xbridge->no_packet_in_rule, &rule, + ctx->xin->xcache != NULL); match: if (rule) { + /* Fill in the cache entry here instead of xlate_recursively + * to make the reference counting more explicit. We take a + * reference in the lookups above if we are going to cache the + * rule. */ + if (ctx->xin->xcache) { + struct xc_entry *entry; + + entry = xlate_cache_add_entry(ctx->xin->xcache, XC_RULE); + entry->u.rule = rule; + } xlate_recursively(ctx, rule); - rule_dpif_unref(rule); } ctx->table_id = old_table_id; @@ -2653,6 +2657,8 @@ xlate_learn_action(struct xlate_ctx *ctx, entry = xlate_cache_add_entry(ctx->xin->xcache, XC_LEARN); entry->u.learn.ofproto = ctx->xin->ofproto; + /* Lookup the learned rule, taking a reference on it. The reference + * is released when this cache entry is deleted. */ rule_dpif_lookup(ctx->xbridge->ofproto, &ctx->xin->flow, NULL, &entry->u.learn.rule, true); } @@ -2678,10 +2684,11 @@ xlate_fin_timeout(struct xlate_ctx *ctx, struct xc_entry *entry; entry = xlate_cache_add_entry(ctx->xin->xcache, XC_FIN_TIMEOUT); + /* XC_RULE already holds a reference on the rule, none is taken + * here. */ entry->u.fin.rule = ctx->rule; entry->u.fin.idle = oft->fin_idle_timeout; entry->u.fin.hard = oft->fin_hard_timeout; - rule_dpif_ref(ctx->rule); } } } @@ -3230,7 +3237,7 @@ xlate_actions__(struct xlate_in *xin, struct xlate_out *xout) ctx.xbridge = xbridge_lookup(xin->ofproto); if (!ctx.xbridge) { - goto out; + return; } ctx.rule = xin->rule; @@ -3263,7 +3270,7 @@ xlate_actions__(struct xlate_in *xin, struct xlate_out *xout) if (!xin->ofpacts && !ctx.rule) { ctx.table_id = rule_dpif_lookup(ctx.xbridge->ofproto, flow, !xin->skip_wildcards ? wc : NULL, - &rule, true); + &rule, ctx.xin->xcache != NULL); if (ctx.xin->resubmit_stats) { rule_dpif_credit_stats(rule, ctx.xin->resubmit_stats); } @@ -3271,7 +3278,6 @@ xlate_actions__(struct xlate_in *xin, struct xlate_out *xout) struct xc_entry *entry; entry = xlate_cache_add_entry(ctx.xin->xcache, XC_RULE); - rule_dpif_ref(rule); entry->u.rule = rule; } ctx.rule = rule; @@ -3309,7 +3315,7 @@ xlate_actions__(struct xlate_in *xin, struct xlate_out *xout) break; case OFPC_FRAG_DROP: - goto out; + return; case OFPC_FRAG_REASM: OVS_NOT_REACHED(); @@ -3456,9 +3462,6 @@ xlate_actions__(struct xlate_in *xin, struct xlate_out *xout) wc->masks.tp_src &= htons(UINT8_MAX); wc->masks.tp_dst &= htons(UINT8_MAX); } - -out: - rule_dpif_unref(rule); } /* Sends 'packet' out 'ofport'. @@ -3580,9 +3583,9 @@ xlate_push_stats(struct xlate_cache *xcache, bool may_learn, struct rule_dpif *rule = entry->u.learn.rule; /* Reset the modified time for a rule that is equivalent to - * the currently cached rule. If the rule is not the exact - * rule wehave cached, update the reference that we have. */ - entry->u.learn.rule = ofproto_dpif_refresh_rule(rule); + * the currently cached rule. If the rule is not the exact + * rule we have cached, update the reference that we have. */ + entry->u.learn.rule = ofproto_dpif_refresh_rule(rule); } break; case XC_NORMAL: @@ -3651,13 +3654,15 @@ xlate_cache_clear(struct xlate_cache *xcache) mbridge_unref(entry->u.mirror.mbridge); break; case XC_LEARN: + /* 'u.learn.rule' is the learned rule. */ rule_dpif_unref(entry->u.learn.rule); break; case XC_NORMAL: free(entry->u.normal.flow); break; case XC_FIN_TIMEOUT: - rule_dpif_unref(entry->u.fin.rule); + /* 'u.fin.rule' is always already held as a XC_RULE, which + * has already released it's reference above. */ break; default: OVS_NOT_REACHED(); -- 2.43.0