Messages in this thread Patch in this message | | | From | Joe Perches <> | Subject | [RFC PATCH 1/3] printk: Use a non-printable ASCII KERN_<LEVEL> initiator | Date | Thu, 24 May 2012 15:49:31 -0700 |
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printk uses <.> to denote the message level. There are thousands of messages in default kernel.
Use ASCII SOH (hex: 01) with no terminator to save 1 byte per message.
This also means that KERN_CONT could be completely removed (#defined to "") as it is no longer serves any real purpose.
Signed-off-by: Joe Perches <joe@perches.com> --- include/linux/printk.h | 23 +++++++++++++---------- kernel/printk.c | 6 +++--- 2 files changed, 16 insertions(+), 13 deletions(-)
diff --git a/include/linux/printk.h b/include/linux/printk.h index 1bec2f7..ad76855 100644 --- a/include/linux/printk.h +++ b/include/linux/printk.h @@ -6,23 +6,26 @@ extern const char linux_banner[]; extern const char linux_proc_banner[]; -#define KERN_EMERG "<0>" /* system is unusable */ -#define KERN_ALERT "<1>" /* action must be taken immediately */ -#define KERN_CRIT "<2>" /* critical conditions */ -#define KERN_ERR "<3>" /* error conditions */ -#define KERN_WARNING "<4>" /* warning conditions */ -#define KERN_NOTICE "<5>" /* normal but significant condition */ -#define KERN_INFO "<6>" /* informational */ -#define KERN_DEBUG "<7>" /* debug-level messages */ +#define KERN_SOH "\001" /* ASCII Start Of Header */ +#define KERN_SOH_ASCII '\001' + +#define KERN_EMERG KERN_SOH "0" /* system is unusable */ +#define KERN_ALERT KERN_SOH "1" /* action must be taken immediately */ +#define KERN_CRIT KERN_SOH "2" /* critical conditions */ +#define KERN_ERR KERN_SOH "3" /* error conditions */ +#define KERN_WARNING KERN_SOH "4" /* warning conditions */ +#define KERN_NOTICE KERN_SOH "5" /* normal but significant condition */ +#define KERN_INFO KERN_SOH "6" /* informational */ +#define KERN_DEBUG KERN_SOH "7" /* debug-level messages */ /* Use the default kernel loglevel */ -#define KERN_DEFAULT "<d>" +#define KERN_DEFAULT KERN_SOH "d" /* * Annotation for a "continued" line of log printout (only done after a * line that had no enclosing \n). Only to be used by core/arch code * during early bootup (a continued line is not SMP-safe otherwise). */ -#define KERN_CONT "<c>" +#define KERN_CONT KERN_SOH "c" extern int console_printk[]; diff --git a/kernel/printk.c b/kernel/printk.c index 32462d2..e96e733 100644 --- a/kernel/printk.c +++ b/kernel/printk.c @@ -1329,7 +1329,7 @@ asmlinkage int vprintk_emit(int facility, int level, } /* strip syslog prefix and extract log level or control flags */ - if (text[0] == '<' && text[1] && text[2] == '>') { + if (text[0] == KERN_SOH_ASCII && text[1]) { switch (text[1]) { case '0' ... '7': if (level == -1) @@ -1337,8 +1337,8 @@ asmlinkage int vprintk_emit(int facility, int level, case 'd': /* KERN_DEFAULT */ prefix = true; case 'c': /* KERN_CONT */ - text += 3; - text_len -= 3; + text += 2; + text_len -= 2; } } -- 1.7.8.111.gad25c.dirty
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