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authorDave Young <hidave.darkstar@gmail.com>2009-09-22 16:43:33 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2009-09-23 07:39:28 -0700
commitaf91322ef3f29ae4114e736e2a72e28b4d619cf9 (patch)
treedebba08531c7dd78b90b5d8f2c03f6bf7c9e7877 /kernel/sysctl.c
parent3a3b6ed2235f2f619889dd6096e24b6d93bf3339 (diff)
downloadlwn-af91322ef3f29ae4114e736e2a72e28b4d619cf9.tar.gz
lwn-af91322ef3f29ae4114e736e2a72e28b4d619cf9.zip
printk: add printk_delay to make messages readable for some scenarios
When syslog is not possible, at the same time there's no serial/net console available, it will be hard to read the printk messages. For example oops/panic/warning messages in shutdown phase. Add a printk delay feature, we can make each printk message delay some milliseconds. Setting the delay by proc/sysctl interface: /proc/sys/kernel/printk_delay The value range from 0 - 10000, default value is 0 [akpm@linux-foundation.org: fix a few things] Signed-off-by: Dave Young <hidave.darkstar@gmail.com> Acked-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel/sysctl.c')
-rw-r--r--kernel/sysctl.c14
1 files changed, 14 insertions, 0 deletions
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 6ba49c7cb128..0dfaa47d7cb6 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -106,6 +106,9 @@ static int __maybe_unused one = 1;
static int __maybe_unused two = 2;
static unsigned long one_ul = 1;
static int one_hundred = 100;
+#ifdef CONFIG_PRINTK
+static int ten_thousand = 10000;
+#endif
/* this is needed for the proc_doulongvec_minmax of vm_dirty_bytes */
static unsigned long dirty_bytes_min = 2 * PAGE_SIZE;
@@ -722,6 +725,17 @@ static struct ctl_table kern_table[] = {
.mode = 0644,
.proc_handler = &proc_dointvec,
},
+ {
+ .ctl_name = CTL_UNNUMBERED,
+ .procname = "printk_delay",
+ .data = &printk_delay_msec,
+ .maxlen = sizeof(int),
+ .mode = 0644,
+ .proc_handler = &proc_dointvec_minmax,
+ .strategy = &sysctl_intvec,
+ .extra1 = &zero,
+ .extra2 = &ten_thousand,
+ },
#endif
{
.ctl_name = KERN_NGROUPS_MAX,