On Sat, 2016-08-06 at 15:56 +0300, Alexey Dobriyan wrote:
> top(1) opens the following files for every PID:
>
> /proc/*/stat
> /proc/*/statm
> /proc/*/status
>
> This patch switches /proc/*/status away from seq_printf().
> The result is 13.5% speedup.
If this is really an important consideration, perhaps
seq_put_decimal_ull (_ll too) should be changed from
void seq_put_decimal_ull(seq_file *, char, unsigned long long)
to
void seq_put_decimal_ull(seq_file *, const char *, unsigned long)
> fs/proc/array.c | 87
> ++++++++++++++++++++++++++++++--------------------------
[]
> @@ -186,51 +186,52 @@ static inline void task_state(struct seq_file *m,
> struct pid_namespace *ns,
> task_unlock(p);
> rcu_read_unlock();
>
> - seq_printf(m,
> - "State:\t%s\n"
> - "Tgid:\t%d\n"
> - "Ngid:\t%d\n"
> - "Pid:\t%d\n"
> - "PPid:\t%d\n"
> - "TracerPid:\t%d\n"
> - "Uid:\t%d\t%d\t%d\t%d\n"
> - "Gid:\t%d\t%d\t%d\t%d\n"
> - "FDSize:\t%d\nGroups:\t",
> - get_task_state(p),
> - tgid, ngid, pid_nr_ns(pid, ns), ppid, tpid,
> - from_kuid_munged(user_ns, cred->uid),
> - from_kuid_munged(user_ns, cred->euid),
> - from_kuid_munged(user_ns, cred->suid),
> - from_kuid_munged(user_ns, cred->fsuid),
> - from_kgid_munged(user_ns, cred->gid),
> - from_kgid_munged(user_ns, cred->egid),
> - from_kgid_munged(user_ns, cred->sgid),
> - from_kgid_munged(user_ns, cred->fsgid),
> - max_fds);
> -
> + seq_printf(m, "State:\t%s", get_task_state(p));
> +
> + seq_puts(m, "\nTgid:\t");
> + seq_put_decimal_ull(m, 0, tgid);
[etc...]
Perhaps too the conversions from %d to %llu are inappropriate
and seq_put_decimal and seq_put_decimal_u should be added.
