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zlib: optimize inffast when copying direct from output 

JFFS2 uses lesser compression ratio and inflate always ends up in "copy
direct from output" case.

This patch tries to optimize the direct copy procedure.  Uses
get_unaligned() but only in one place.

The copy loop just above this one can also use this optimization, but I
havn't done so as I have not tested if it is a win there too.

On my MPC8321 this is about 17% faster on my JFFS2 root FS than the
original.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Joakim Tjernlund <Joakim.Tjernlund@transmode.se>
Cc: Roel Kluin <roel.kluin@gmail.com>
Cc: Richard Purdie <rpurdie@rpsys.net>
Cc: David Woodhouse <dwmw2@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
hifive-unleashed-5.1
Joakim Tjernlund 2010-01-08 14:42:40 -08:00 committed by Linus Torvalds
parent 129182e562
commit ac4c2a3bbe
2 changed files with 47 additions and 12 deletions
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4
arch/powerpc/boot/Makefile
View File

@ -20,7 +20,7 @@
all: $(obj)/zImage
BOOTCFLAGS := -Wall -Wundef -Wstrict-prototypes -Wno-trigraphs \
-fno-strict-aliasing -Os -msoft-float -pipe \
-fno-strict-aliasing -Os -msoft-float -pipe -D__KERNEL__\
-fomit-frame-pointer -fno-builtin -fPIC -nostdinc \
-isystem $(shell $(CROSS32CC) -print-file-name=include)
BOOTAFLAGS := -D__ASSEMBLY__ $(BOOTCFLAGS) -traditional -nostdinc
@ -34,6 +34,8 @@ BOOTCFLAGS += -fno-stack-protector
endif
BOOTCFLAGS += -I$(obj) -I$(srctree)/$(obj)
BOOTCFLAGS += -include include/linux/autoconf.h -Iarch/powerpc/include
BOOTCFLAGS += -Iinclude
DTS_FLAGS ?= -p 1024

55
lib/zlib_inflate/inffast.c
View File

@ -4,6 +4,8 @@
*/
#include <linux/zutil.h>
#include <asm/unaligned.h>
#include <asm/byteorder.h>
#include "inftrees.h"
#include "inflate.h"
#include "inffast.h"
@ -24,9 +26,11 @@
#ifdef POSTINC
# define OFF 0
# define PUP(a) *(a)++
# define UP_UNALIGNED(a) get_unaligned((a)++)
#else
# define OFF 1
# define PUP(a) *++(a)
# define UP_UNALIGNED(a) get_unaligned(++(a))
#endif
/*
@ -239,18 +243,47 @@ void inflate_fast(z_streamp strm, unsigned start)
}
}
else {
unsigned short *sout;
unsigned long loops;
from = out - dist; /* copy direct from output */
do { /* minimum length is three */
PUP(out) = PUP(from);
PUP(out) = PUP(from);
PUP(out) = PUP(from);
len -= 3;
} while (len > 2);
if (len) {
PUP(out) = PUP(from);
if (len > 1)
PUP(out) = PUP(from);
}
/* minimum length is three */
/* Align out addr */
if (!((long)(out - 1 + OFF) & 1)) {
PUP(out) = PUP(from);
len--;
}
sout = (unsigned short *)(out - OFF);
if (dist > 2) {
unsigned short *sfrom;
sfrom = (unsigned short *)(from - OFF);
loops = len >> 1;
do
PUP(sout) = UP_UNALIGNED(sfrom);
while (--loops);
out = (unsigned char *)sout + OFF;
from = (unsigned char *)sfrom + OFF;
} else { /* dist == 1 or dist == 2 */
unsigned short pat16;
pat16 = *(sout-2+2*OFF);
if (dist == 1)
#if defined(__BIG_ENDIAN)
pat16 = (pat16 & 0xff) | ((pat16 & 0xff) << 8);
#elif defined(__LITTLE_ENDIAN)
pat16 = (pat16 & 0xff00) | ((pat16 & 0xff00) >> 8);
#else
#error __BIG_ENDIAN nor __LITTLE_ENDIAN is defined
#endif
loops = len >> 1;
do
PUP(sout) = pat16;
while (--loops);
out = (unsigned char *)sout + OFF;
}
if (len & 1)
PUP(out) = PUP(from);
}
}
else if ((op & 64) == 0) { /* 2nd level distance code */