linux-kernel - [PATCH 1/1] boot: Enhance performance by eliminating unnecessary calls to printf()

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Date:	Sun, 5 Jun 2011 18:40:38 -0600
From:	Jean Sacren <sakiwit@...il.com>
To:	hpa@...ux.intel.com
Cc:	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: [PATCH 1/1] boot: Enhance performance by eliminating unnecessary
 calls to printf()

Hi,

Repeated calling to printf() for 13 times is a dire waste of CPU cycles.
For performance, combine all those calls into one while source code
formatting is preserved for readability.

Compile tested only.

Signed-off-by: Jean Sacren <sakiwit@...il.com>
---
 arch/x86/boot/compressed/mkpiggy.c |   30 ++++++++++++++++--------------
 1 files changed, 16 insertions(+), 14 deletions(-)

diff --git a/arch/x86/boot/compressed/mkpiggy.c b/arch/x86/boot/compressed/mkpiggy.c
index 46a8238..0b6d82c 100644
--- a/arch/x86/boot/compressed/mkpiggy.c
+++ b/arch/x86/boot/compressed/mkpiggy.c
@@ -44,6 +44,7 @@ int main(int argc, char *argv[])
 	long ilen;
 	unsigned long offs;
 	FILE *f;
+	char *msg;
 
 	if (argc < 2) {
 		fprintf(stderr, "Usage: %s compressed_file\n", argv[0]);
@@ -82,21 +83,22 @@ int main(int argc, char *argv[])
 	offs += 64*1024 + 128;	/* Add 64K + 128 bytes slack */
 	offs = (offs+4095) & ~4095; /* Round to a 4K boundary */
 
-	printf(".section \".rodata..compressed\",\"a\",@progbits\n");
-	printf(".globl z_input_len\n");
-	printf("z_input_len = %lu\n", ilen);
-	printf(".globl z_output_len\n");
-	printf("z_output_len = %lu\n", (unsigned long)olen);
-	printf(".globl z_extract_offset\n");
-	printf("z_extract_offset = 0x%lx\n", offs);
 	/* z_extract_offset_negative allows simplification of head_32.S */
-	printf(".globl z_extract_offset_negative\n");
-	printf("z_extract_offset_negative = -0x%lx\n", offs);
-
-	printf(".globl input_data, input_data_end\n");
-	printf("input_data:\n");
-	printf(".incbin \"%s\"\n", argv[1]);
-	printf("input_data_end:\n");
+	msg = ".section \".rodata..compressed\",\"a\",@progbits\n"
+		".globl z_input_len\n"
+		"z_input_len = %lu\n"
+		".globl z_output_len\n"
+		"z_output_len = %lu\n"
+		".globl z_extract_offset\n"
+		"z_extract_offset = 0x%lx\n"
+		".globl z_extract_offset_negative\n"
+		"z_extract_offset_negative = -0x%lx\n"
+		".globl input_data, input_data_end\n"
+		"input_data:\n"
+		".incbin \"%s\"\n"
+		"input_data_end:\n";
+
+	printf(msg, ilen, (unsigned long)olen, offs, offs, argv[1]);
 
 	return 0;
 }
-- 
1.7.2.2


-- 
Jean Sacren
--
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