From 51de4d90852ba4cfa5743594ec4a7f158b52dc43 Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Wed, 6 Dec 2006 20:36:54 -0800 Subject: [PATCH] [PATCH] taskstats: use nla_reserve() for reply assembling Currently taskstats_user_cmd()/taskstats_exit() do: 1) allocate stats 2) fill stats 3) make a temporary copy on stack (236 bytes) 4) copy that copy to skb 5) free stats With the help of nla_reserve() we can operate on skb->data directly, thus avoiding all these steps except 2). So, before this patch: // copy *stats to skb->data int mk_reply(skb, ..., struct taskstats *stats); fill_pid(stats); mk_reply(skb, ..., stats); After: // return a pointer to skb->data struct taskstats *mk_reply(skb, ...); stat = mk_reply(skb, ...); fill_pid(stats); Shrinks taskatsks.o by 162 bytes. A stupid benchmark (send one million TASKSTATS_CMD_ATTR_PID) shows the real user sys before: 4.02 0.06 3.96 4.02 0.04 3.98 4.02 0.04 3.97 after: 3.86 0.08 3.78 3.88 0.10 3.77 3.89 0.09 3.80 but this looks suspiciously good. Signed-off-by: Oleg Nesterov Acked-by: Shailabh Nagar Cc: Balbir Singh Cc: Jay Lan Cc: Thomas Graf Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/taskstats.c | 86 ++++++++++++++++++++++++---------------------- 1 file changed, 44 insertions(+), 42 deletions(-) diff --git a/kernel/taskstats.c b/kernel/taskstats.c index d2a41339f37b..b0aad99c4f8d 100644 --- a/kernel/taskstats.c +++ b/kernel/taskstats.c @@ -185,6 +185,7 @@ static int fill_pid(pid_t pid, struct task_struct *tsk, } else get_task_struct(tsk); + memset(stats, 0, sizeof(*stats)); /* * Each accounting subsystem adds calls to its functions to * fill in relevant parts of struct taskstsats as follows @@ -227,6 +228,8 @@ static int fill_tgid(pid_t tgid, struct task_struct *first, if (first->signal->stats) memcpy(stats, first->signal->stats, sizeof(*stats)); + else + memset(stats, 0, sizeof(*stats)); tsk = first; do { @@ -343,9 +346,9 @@ static int parse(struct nlattr *na, cpumask_t *mask) return ret; } -static int mk_reply(struct sk_buff *skb, int type, u32 pid, struct taskstats *stats) +static struct taskstats *mk_reply(struct sk_buff *skb, int type, u32 pid) { - struct nlattr *na; + struct nlattr *na, *ret; int aggr; aggr = TASKSTATS_TYPE_AGGR_TGID; @@ -353,20 +356,23 @@ static int mk_reply(struct sk_buff *skb, int type, u32 pid, struct taskstats *st aggr = TASKSTATS_TYPE_AGGR_PID; na = nla_nest_start(skb, aggr); - NLA_PUT_U32(skb, type, pid); - NLA_PUT_TYPE(skb, struct taskstats, TASKSTATS_TYPE_STATS, *stats); + if (nla_put(skb, type, sizeof(pid), &pid) < 0) + goto err; + ret = nla_reserve(skb, TASKSTATS_TYPE_STATS, sizeof(struct taskstats)); + if (!ret) + goto err; nla_nest_end(skb, na); - return 0; -nla_put_failure: - return -1; + return nla_data(ret); +err: + return NULL; } static int taskstats_user_cmd(struct sk_buff *skb, struct genl_info *info) { int rc = 0; struct sk_buff *rep_skb; - struct taskstats stats; + struct taskstats *stats; void *reply; size_t size; cpumask_t mask; @@ -389,36 +395,36 @@ static int taskstats_user_cmd(struct sk_buff *skb, struct genl_info *info) size = nla_total_size(sizeof(u32)) + nla_total_size(sizeof(struct taskstats)) + nla_total_size(0); - memset(&stats, 0, sizeof(stats)); rc = prepare_reply(info, TASKSTATS_CMD_NEW, &rep_skb, &reply, size); if (rc < 0) return rc; + rc = -EINVAL; if (info->attrs[TASKSTATS_CMD_ATTR_PID]) { u32 pid = nla_get_u32(info->attrs[TASKSTATS_CMD_ATTR_PID]); - rc = fill_pid(pid, NULL, &stats); - if (rc < 0) - goto err; + stats = mk_reply(rep_skb, TASKSTATS_TYPE_PID, pid); + if (!stats) + goto nla_err; - if (mk_reply(rep_skb, TASKSTATS_TYPE_PID, pid, &stats)) - goto nla_put_failure; + rc = fill_pid(pid, NULL, stats); + if (rc < 0) + goto nla_err; } else if (info->attrs[TASKSTATS_CMD_ATTR_TGID]) { u32 tgid = nla_get_u32(info->attrs[TASKSTATS_CMD_ATTR_TGID]); - rc = fill_tgid(tgid, NULL, &stats); - if (rc < 0) - goto err; + stats = mk_reply(rep_skb, TASKSTATS_TYPE_TGID, tgid); + if (!stats) + goto nla_err; - if (mk_reply(rep_skb, TASKSTATS_TYPE_TGID, tgid, &stats)) - goto nla_put_failure; - } else { - rc = -EINVAL; + rc = fill_tgid(tgid, NULL, stats); + if (rc < 0) + goto nla_err; + } else goto err; - } return send_reply(rep_skb, info->snd_pid); -nla_put_failure: - rc = genlmsg_cancel(rep_skb, reply); +nla_err: + genlmsg_cancel(rep_skb, reply); err: nlmsg_free(rep_skb); return rc; @@ -453,7 +459,7 @@ void taskstats_exit(struct task_struct *tsk, int group_dead) { int rc; struct listener_list *listeners; - struct taskstats *tidstats; + struct taskstats *stats; struct sk_buff *rep_skb; void *reply; size_t size; @@ -480,20 +486,17 @@ void taskstats_exit(struct task_struct *tsk, int group_dead) if (list_empty(&listeners->list)) return; - tidstats = kmem_cache_zalloc(taskstats_cache, GFP_KERNEL); - if (!tidstats) - return; - rc = prepare_reply(NULL, TASKSTATS_CMD_NEW, &rep_skb, &reply, size); if (rc < 0) - goto free_stats; + return; - rc = fill_pid(tsk->pid, tsk, tidstats); + stats = mk_reply(rep_skb, TASKSTATS_TYPE_PID, tsk->pid); + if (!stats) + goto nla_err; + + rc = fill_pid(tsk->pid, tsk, stats); if (rc < 0) - goto err_skb; - - if (mk_reply(rep_skb, TASKSTATS_TYPE_PID, tsk->pid, tidstats)) - goto nla_put_failure; + goto nla_err; /* * Doesn't matter if tsk is the leader or the last group member leaving @@ -501,20 +504,19 @@ void taskstats_exit(struct task_struct *tsk, int group_dead) if (!is_thread_group || !group_dead) goto send; - if (mk_reply(rep_skb, TASKSTATS_TYPE_TGID, tsk->tgid, tsk->signal->stats)) - goto nla_put_failure; + stats = mk_reply(rep_skb, TASKSTATS_TYPE_TGID, tsk->tgid); + if (!stats) + goto nla_err; + + memcpy(stats, tsk->signal->stats, sizeof(*stats)); send: send_cpu_listeners(rep_skb, listeners); -free_stats: - kmem_cache_free(taskstats_cache, tidstats); return; -nla_put_failure: +nla_err: genlmsg_cancel(rep_skb, reply); -err_skb: nlmsg_free(rep_skb); - goto free_stats; } static struct genl_ops taskstats_ops = {