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zlib: optimize inffast when copying direct from output

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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>
This commit is contained in:
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 */