[PATCH-2.4] make log buffer length selectable

[Willy Tarreau <willy@w.ods.org>]

On Mon, Aug 25, 2003 at 04:48:30AM -0700, Marcelo Tosatti wrote:
> final:
> 
> - 2.4.22-rc4 was released as 2.4.22 with no changes.

Hi Marcelo,

as you requested, here is the log_buf_len patch for inclusion in 23-pre.

Cheers,
Willy


diff -urN wt10-pre3/Documentation/Configure.help wt10-pre3-log-buf-len/Documentation/Configure.help
--- wt10-pre3/Documentation/Configure.help	Wed Mar 19 09:58:25 2003
+++ wt10-pre3-log-buf-len/Documentation/Configure.help	Tue Mar 25 08:20:35 2003
@@ -25231,6 +25231,19 @@
   output to the second serial port on these devices.  Saying N will
   cause the debug messages to appear on the first serial port.
 
+Kernel log buffer length shift
+CONFIG_LOG_BUF_SHIFT
+  The kernel log buffer has a fixed size of :
+      64 kB (2^16) on MULTIQUAD and IA64,
+     128 kB (2^17) on S390
+      32 kB (2^15) on SMP systems
+      16 kB (2^14) on UP systems
+
+  You have the ability to change this size with this paramter which
+  fixes the bit shift of to get the buffer length (which must be a
+  power of 2). Eg: a value of 16 sets the buffer to 64 kB (2^16).
+  The default value of 0 uses standard values above.
+
 Disable pgtable cache
 CONFIG_NO_PGT_CACHE
   Normally the kernel maintains a `quicklist' of preallocated
diff -urN wt10-pre3/arch/i386/config.in wt10-pre3-log-buf-len/arch/i386/config.in
--- wt10-pre3/arch/i386/config.in	Wed Mar 19 09:58:25 2003
+++ wt10-pre3-log-buf-len/arch/i386/config.in	Tue Mar 25 08:25:12 2003
@@ -508,6 +508,8 @@
     string '   Initial kernel command line' CONFIG_CMDLINE "root=301 ro"
 fi
 
+int 'Kernel messages buffer length shift (0 = default)' CONFIG_LOG_BUF_SHIFT 0
+
 endmenu
 
 source lib/Config.in
diff -urN wt10-pre3/kernel/printk.c wt10-pre3-log-buf-len/kernel/printk.c
--- wt10-pre3/kernel/printk.c	Wed Mar 19 09:58:20 2003
+++ wt10-pre3-log-buf-len/kernel/printk.c	Tue Mar 25 08:14:55 2003
@@ -29,6 +29,7 @@
 
 #include <asm/uaccess.h>
 
+#if !defined(CONFIG_LOG_BUF_SHIFT) || (CONFIG_LOG_BUF_SHIFT - 0 == 0)
 #if defined(CONFIG_MULTIQUAD) || defined(CONFIG_IA64)
 #define LOG_BUF_LEN	(65536)
 #elif defined(CONFIG_ARCH_S390)
@@ -37,6 +38,9 @@
 #define LOG_BUF_LEN	(32768)
 #else	
 #define LOG_BUF_LEN	(16384)			/* This must be a power of two */
+#endif
+#else /* CONFIG_LOG_BUF_SHIFT */
+#define LOG_BUF_LEN (1 << CONFIG_LOG_BUF_SHIFT)
 #endif
 
 #define LOG_BUF_MASK	(LOG_BUF_LEN-1)