[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 <oleg@tv-sign.ru> Acked-by: Shailabh Nagar <nagar@watson.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Jay Lan <jlan@sgi.com> Cc: Thomas Graf <tgraf@suug.ch> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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68062b86fc
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51de4d9085
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@ -185,6 +185,7 @@ static int fill_pid(pid_t pid, struct task_struct *tsk,
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} else
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get_task_struct(tsk);
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memset(stats, 0, sizeof(*stats));
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/*
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* Each accounting subsystem adds calls to its functions to
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* fill in relevant parts of struct taskstsats as follows
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@ -227,6 +228,8 @@ static int fill_tgid(pid_t tgid, struct task_struct *first,
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if (first->signal->stats)
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memcpy(stats, first->signal->stats, sizeof(*stats));
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else
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memset(stats, 0, sizeof(*stats));
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tsk = first;
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do {
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@ -343,9 +346,9 @@ static int parse(struct nlattr *na, cpumask_t *mask)
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return ret;
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}
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static int mk_reply(struct sk_buff *skb, int type, u32 pid, struct taskstats *stats)
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static struct taskstats *mk_reply(struct sk_buff *skb, int type, u32 pid)
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{
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struct nlattr *na;
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struct nlattr *na, *ret;
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int aggr;
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aggr = TASKSTATS_TYPE_AGGR_TGID;
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@ -353,20 +356,23 @@ static int mk_reply(struct sk_buff *skb, int type, u32 pid, struct taskstats *st
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aggr = TASKSTATS_TYPE_AGGR_PID;
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na = nla_nest_start(skb, aggr);
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NLA_PUT_U32(skb, type, pid);
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NLA_PUT_TYPE(skb, struct taskstats, TASKSTATS_TYPE_STATS, *stats);
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if (nla_put(skb, type, sizeof(pid), &pid) < 0)
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goto err;
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ret = nla_reserve(skb, TASKSTATS_TYPE_STATS, sizeof(struct taskstats));
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if (!ret)
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goto err;
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nla_nest_end(skb, na);
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return 0;
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nla_put_failure:
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return -1;
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return nla_data(ret);
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err:
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return NULL;
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}
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static int taskstats_user_cmd(struct sk_buff *skb, struct genl_info *info)
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{
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int rc = 0;
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struct sk_buff *rep_skb;
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struct taskstats stats;
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struct taskstats *stats;
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void *reply;
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size_t size;
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cpumask_t mask;
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@ -389,36 +395,36 @@ static int taskstats_user_cmd(struct sk_buff *skb, struct genl_info *info)
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size = nla_total_size(sizeof(u32)) +
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nla_total_size(sizeof(struct taskstats)) + nla_total_size(0);
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memset(&stats, 0, sizeof(stats));
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rc = prepare_reply(info, TASKSTATS_CMD_NEW, &rep_skb, &reply, size);
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if (rc < 0)
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return rc;
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rc = -EINVAL;
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if (info->attrs[TASKSTATS_CMD_ATTR_PID]) {
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u32 pid = nla_get_u32(info->attrs[TASKSTATS_CMD_ATTR_PID]);
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rc = fill_pid(pid, NULL, &stats);
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if (rc < 0)
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goto err;
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stats = mk_reply(rep_skb, TASKSTATS_TYPE_PID, pid);
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if (!stats)
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goto nla_err;
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if (mk_reply(rep_skb, TASKSTATS_TYPE_PID, pid, &stats))
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goto nla_put_failure;
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rc = fill_pid(pid, NULL, stats);
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if (rc < 0)
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goto nla_err;
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} else if (info->attrs[TASKSTATS_CMD_ATTR_TGID]) {
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u32 tgid = nla_get_u32(info->attrs[TASKSTATS_CMD_ATTR_TGID]);
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rc = fill_tgid(tgid, NULL, &stats);
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if (rc < 0)
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goto err;
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stats = mk_reply(rep_skb, TASKSTATS_TYPE_TGID, tgid);
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if (!stats)
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goto nla_err;
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if (mk_reply(rep_skb, TASKSTATS_TYPE_TGID, tgid, &stats))
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goto nla_put_failure;
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} else {
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rc = -EINVAL;
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rc = fill_tgid(tgid, NULL, stats);
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if (rc < 0)
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goto nla_err;
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} else
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goto err;
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}
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return send_reply(rep_skb, info->snd_pid);
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nla_put_failure:
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rc = genlmsg_cancel(rep_skb, reply);
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nla_err:
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genlmsg_cancel(rep_skb, reply);
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err:
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nlmsg_free(rep_skb);
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return rc;
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@ -453,7 +459,7 @@ void taskstats_exit(struct task_struct *tsk, int group_dead)
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{
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int rc;
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struct listener_list *listeners;
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struct taskstats *tidstats;
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struct taskstats *stats;
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struct sk_buff *rep_skb;
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void *reply;
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size_t size;
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@ -480,20 +486,17 @@ void taskstats_exit(struct task_struct *tsk, int group_dead)
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if (list_empty(&listeners->list))
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return;
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tidstats = kmem_cache_zalloc(taskstats_cache, GFP_KERNEL);
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if (!tidstats)
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return;
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rc = prepare_reply(NULL, TASKSTATS_CMD_NEW, &rep_skb, &reply, size);
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if (rc < 0)
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goto free_stats;
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return;
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rc = fill_pid(tsk->pid, tsk, tidstats);
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stats = mk_reply(rep_skb, TASKSTATS_TYPE_PID, tsk->pid);
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if (!stats)
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goto nla_err;
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rc = fill_pid(tsk->pid, tsk, stats);
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if (rc < 0)
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goto err_skb;
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if (mk_reply(rep_skb, TASKSTATS_TYPE_PID, tsk->pid, tidstats))
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goto nla_put_failure;
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goto nla_err;
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/*
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* Doesn't matter if tsk is the leader or the last group member leaving
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@ -501,20 +504,19 @@ void taskstats_exit(struct task_struct *tsk, int group_dead)
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if (!is_thread_group || !group_dead)
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goto send;
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if (mk_reply(rep_skb, TASKSTATS_TYPE_TGID, tsk->tgid, tsk->signal->stats))
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goto nla_put_failure;
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stats = mk_reply(rep_skb, TASKSTATS_TYPE_TGID, tsk->tgid);
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if (!stats)
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goto nla_err;
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memcpy(stats, tsk->signal->stats, sizeof(*stats));
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send:
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send_cpu_listeners(rep_skb, listeners);
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free_stats:
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kmem_cache_free(taskstats_cache, tidstats);
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return;
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nla_put_failure:
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nla_err:
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genlmsg_cancel(rep_skb, reply);
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err_skb:
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nlmsg_free(rep_skb);
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goto free_stats;
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}
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static struct genl_ops taskstats_ops = {
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