On Tue, 2009-11-10 at 10:00 +0100, Joakim Tjernlund wrote:
> 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.
> ---
>
> Would like some testing of the PowerPC boot wrapper and
> a LE target before sending it upstream.
Well, you should probably submit that patch to lkml then :-)
I'm not sure its going to work to use get_unaligned() like that on all
archs .. it might be definitely something to discuss on some more
appropriate mailing list.
Cheers,
Ben.
> arch/powerpc/boot/Makefile | 4 ++-
> lib/zlib_inflate/inffast.c | 48 +++++++++++++++++++++++++++++++++----------
> 2 files changed, 40 insertions(+), 12 deletions(-)
>
> diff --git a/arch/powerpc/boot/Makefile b/arch/powerpc/boot/Makefile
> index 9ae7b7e..98e4c4f 100644
> --- a/arch/powerpc/boot/Makefile
> +++ b/arch/powerpc/boot/Makefile
> @@ -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
>
> diff --git a/lib/zlib_inflate/inffast.c b/lib/zlib_inflate/inffast.c
> index 8550b0c..0c7fa3d 100644
> --- a/lib/zlib_inflate/inffast.c
> +++ b/lib/zlib_inflate/inffast.c
> @@ -4,6 +4,7 @@
> */
>
> #include <linux/zutil.h>
> +#include <asm/unaligned.h>
> #include "inftrees.h"
> #include "inflate.h"
> #include "inffast.h"
> @@ -24,9 +25,11 @@
> #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 +242,41 @@ 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)
> + pat16 = (pat16 & 0xff) | ((pat16 & 0xff ) << 8);
> + 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 */
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