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Message-ID: <20160806125608.GB1187@p183.telecom.by>
Date: Sat, 6 Aug 2016 15:56:11 +0300
From: Alexey Dobriyan <adobriyan@...il.com>
To: akpm@...ux-foundation.org
Cc: linux-kernel@...r.kernel.org
Subject: [PATCH] proc: faster /proc/*/status
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.
Benchmark is open("/proc/self/status")+read+close 1.000.000 million times.
BEFORE
$ perf stat -r 10 taskset -c 3 ./proc-self-status
Performance counter stats for 'taskset -c 3 ./proc-self-status' (10 runs):
10748.474301 task-clock (msec) # 0.954 CPUs utilized ( +- 0.91% )
12 context-switches # 0.001 K/sec ( +- 1.09% )
1 cpu-migrations # 0.000 K/sec
104 page-faults # 0.010 K/sec ( +- 0.45% )
37,424,127,876 cycles # 3.482 GHz ( +- 0.04% )
8,453,010,029 stalled-cycles-frontend # 22.59% frontend cycles idle ( +- 0.12% )
3,747,609,427 stalled-cycles-backend # 10.01% backend cycles idle ( +- 0.68% )
65,632,764,147 instructions # 1.75 insn per cycle
# 0.13 stalled cycles per insn ( +- 0.00% )
13,981,324,775 branches # 1300.773 M/sec ( +- 0.00% )
138,967,110 branch-misses # 0.99% of all branches ( +- 0.18% )
11.263885428 seconds time elapsed ( +- 0.04% )
^^^^^^^^^^^^
AFTER
$ perf stat -r 10 taskset -c 3 ./proc-self-status
Performance counter stats for 'taskset -c 3 ./proc-self-status' (10 runs):
9010.521776 task-clock (msec) # 0.925 CPUs utilized ( +- 1.54% )
11 context-switches # 0.001 K/sec ( +- 1.54% )
1 cpu-migrations # 0.000 K/sec ( +- 11.11% )
103 page-faults # 0.011 K/sec ( +- 0.60% )
32,352,310,603 cycles # 3.591 GHz ( +- 0.07% )
7,849,199,578 stalled-cycles-frontend # 24.26% frontend cycles idle ( +- 0.27% )
3,269,738,842 stalled-cycles-backend # 10.11% backend cycles idle ( +- 0.73% )
56,012,163,567 instructions # 1.73 insn per cycle
# 0.14 stalled cycles per insn ( +- 0.00% )
11,735,778,795 branches # 1302.453 M/sec ( +- 0.00% )
98,084,459 branch-misses # 0.84% of all branches ( +- 0.28% )
9.741247736 seconds time elapsed ( +- 0.07% )
^^^^^^^^^^^
Signed-off-by: Alexey Dobriyan <adobriyan@...il.com>
---
fs/proc/array.c | 87 ++++++++++++++++++++++++++++++--------------------------
1 file changed, 47 insertions(+), 40 deletions(-)
--- a/fs/proc/array.c
+++ b/fs/proc/array.c
@@ -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);
+ seq_puts(m, "\nNgid:\t");
+ seq_put_decimal_ull(m, 0, ngid);
+ seq_puts(m, "\nPid:\t");
+ seq_put_decimal_ull(m, 0, pid_nr_ns(pid, ns));
+ seq_puts(m, "\nPPid:\t");
+ seq_put_decimal_ull(m, 0, ppid);
+ seq_puts(m, "\nTracerPid:\t");
+ seq_put_decimal_ull(m, 0, tpid);
+ seq_puts(m, "\nUid:");
+ seq_put_decimal_ull(m, '\t', from_kuid_munged(user_ns, cred->uid));
+ seq_put_decimal_ull(m, '\t', from_kuid_munged(user_ns, cred->euid));
+ seq_put_decimal_ull(m, '\t', from_kuid_munged(user_ns, cred->suid));
+ seq_put_decimal_ull(m, '\t', from_kuid_munged(user_ns, cred->fsuid));
+ seq_puts(m, "\nGid:");
+ seq_put_decimal_ull(m, '\t', from_kgid_munged(user_ns, cred->gid));
+ seq_put_decimal_ull(m, '\t', from_kgid_munged(user_ns, cred->egid));
+ seq_put_decimal_ull(m, '\t', from_kgid_munged(user_ns, cred->sgid));
+ seq_put_decimal_ull(m, '\t', from_kgid_munged(user_ns, cred->fsgid));
+ seq_puts(m, "\nFDSize:\t");
+ seq_put_decimal_ull(m, 0, max_fds);
+
+ seq_puts(m, "\nGroups:\t");
group_info = cred->group_info;
for (g = 0; g < group_info->ngroups; g++)
- seq_printf(m, "%d ",
- from_kgid_munged(user_ns, GROUP_AT(group_info, g)));
+ seq_put_decimal_ull(m, g ? ' ' : 0, from_kgid_munged(user_ns, GROUP_AT(group_info, g)));
put_cred(cred);
+ /* Trailing space shouldn't have been added in the first place. */
+ seq_putc(m, ' ');
#ifdef CONFIG_PID_NS
seq_puts(m, "\nNStgid:");
for (g = ns->level; g <= pid->level; g++)
- seq_printf(m, "\t%d",
- task_tgid_nr_ns(p, pid->numbers[g].ns));
+ seq_put_decimal_ull(m, '\t', task_tgid_nr_ns(p, pid->numbers[g].ns));
seq_puts(m, "\nNSpid:");
for (g = ns->level; g <= pid->level; g++)
- seq_printf(m, "\t%d",
- task_pid_nr_ns(p, pid->numbers[g].ns));
+ seq_put_decimal_ull(m, '\t', task_pid_nr_ns(p, pid->numbers[g].ns));
seq_puts(m, "\nNSpgid:");
for (g = ns->level; g <= pid->level; g++)
- seq_printf(m, "\t%d",
- task_pgrp_nr_ns(p, pid->numbers[g].ns));
+ seq_put_decimal_ull(m, '\t', task_pgrp_nr_ns(p, pid->numbers[g].ns));
seq_puts(m, "\nNSsid:");
for (g = ns->level; g <= pid->level; g++)
- seq_printf(m, "\t%d",
- task_session_nr_ns(p, pid->numbers[g].ns));
+ seq_put_decimal_ull(m, '\t', task_session_nr_ns(p, pid->numbers[g].ns));
#endif
seq_putc(m, '\n');
}
@@ -299,11 +300,14 @@ static inline void task_sig(struct seq_file *m, struct task_struct *p)
unlock_task_sighand(p, &flags);
}
- seq_printf(m, "Threads:\t%d\n", num_threads);
- seq_printf(m, "SigQ:\t%lu/%lu\n", qsize, qlim);
+ seq_puts(m, "Threads:\t");
+ seq_put_decimal_ull(m, 0, num_threads);
+ seq_puts(m, "\nSigQ:\t");
+ seq_put_decimal_ull(m, 0, qsize);
+ seq_put_decimal_ull(m, '/', qlim);
/* render them all */
- render_sigset_t(m, "SigPnd:\t", &pending);
+ render_sigset_t(m, "\nSigPnd:\t", &pending);
render_sigset_t(m, "ShdPnd:\t", &shpending);
render_sigset_t(m, "SigBlk:\t", &blocked);
render_sigset_t(m, "SigIgn:\t", &ignored);
@@ -348,17 +352,20 @@ static inline void task_cap(struct seq_file *m, struct task_struct *p)
static inline void task_seccomp(struct seq_file *m, struct task_struct *p)
{
#ifdef CONFIG_SECCOMP
- seq_printf(m, "Seccomp:\t%d\n", p->seccomp.mode);
+ seq_puts(m, "Seccomp:\t");
+ seq_put_decimal_ull(m, 0, p->seccomp.mode);
+ seq_putc(m, '\n');
#endif
}
static inline void task_context_switch_counts(struct seq_file *m,
struct task_struct *p)
{
- seq_printf(m, "voluntary_ctxt_switches:\t%lu\n"
- "nonvoluntary_ctxt_switches:\t%lu\n",
- p->nvcsw,
- p->nivcsw);
+ seq_puts(m, "voluntary_ctxt_switches:\t");
+ seq_put_decimal_ull(m, 0, p->nvcsw);
+ seq_puts(m, "\nnonvoluntary_ctxt_switches:\t");
+ seq_put_decimal_ull(m, 0, p->nivcsw);
+ seq_putc(m, '\n');
}
static void task_cpus_allowed(struct seq_file *m, struct task_struct *task)
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