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[PATCH] taskstats: use nla_reserve() for reply assembling

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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>
This commit is contained in:
Oleg Nesterov 2006-12-06 20:36:54 -08:00 committed by Linus Torvalds
parent 68062b86fc
commit 51de4d9085
1 changed files with 44 additions and 42 deletions
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86
kernel/taskstats.c
View file

@ -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 = {