The patch titled
zlib: optimize inffast when copying direct from output
has been added to the -mm tree. Its filename is
zlib-optimize-inffast-when-copying-direct-from-output.patch
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------------------------------------------------------
Subject: zlib: optimize inffast when copying direct from output
From: Joakim Tjernlund <Joakim.Tjernlund@xxxxxxxxxxxx>
JFFS2 uses lesser compression ratio and inflate always ends up in "copy
direct from output" case.
This patch tries to optimize the copy procedure for arch's that have
CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS defined. On my MPC8321 this is
about 14% faster on my JFFS2 root FS than the original.
Signed-off-by: Joakim Tjernlund <Joakim.Tjernlund@xxxxxxxxxxxx>
Cc: Alain Knaff <alain@xxxxxxxx>
Cc: H. Peter Anvin <hpa@xxxxxxxxx>
Cc: Richard Purdie <rpurdie@xxxxxxxxx>
Cc: David Woodhouse <dwmw2@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
diff -puN lib/zlib_inflate/inffast.c~zlib-optimize-inffast-when-copying-direct-from-output lib/zlib_inflate/inffast.c
--- a/lib/zlib_inflate/inffast.c~zlib-optimize-inffast-when-copying-direct-from-output
+++ a/lib/zlib_inflate/inffast.c
@@ -240,6 +240,40 @@ void inflate_fast(z_streamp strm, unsign
}
else {
from = out - dist; /* copy direct from output */
+#ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
+ /* minimum length is three */
+ if (dist > 2 ) {
+ unsigned short *sout = (unsigned short *)(out - OFF);
+ unsigned short *sfrom = (unsigned short *)(from - OFF);
+ unsigned long loops = len >> 1;
+
+ do
+ PUP(sout) = PUP(sfrom);
+ while (--loops);
+ out = (unsigned char *)sout + OFF;
+ from = (unsigned char *)sfrom + OFF;
+ if (len & 1)
+ PUP(out) = PUP(from);
+ } else if (dist == 2) {
+ unsigned short *sout = (unsigned short *)(out - OFF);
+ unsigned short pat16;
+ unsigned long loops = len >> 1;
+
+ pat16 = *(sout-2+2*OFF);
+ do
+ PUP(sout) = pat16;
+ while (--loops);
+ out = (unsigned char *)sout + OFF;
+ if (len & 1)
+ PUP(out) = PUP(from);
+ } else {
+ unsigned char pat8 = *(out - 1 + OFF);
+
+ do {
+ PUP(out) = pat8;
+ } while (--len);
+ }
+#else
do { /* minimum length is three */
PUP(out) = PUP(from);
PUP(out) = PUP(from);
@@ -251,6 +285,7 @@ void inflate_fast(z_streamp strm, unsign
if (len > 1)
PUP(out) = PUP(from);
}
+#endif
}
}
else if ((op & 64) == 0) { /* 2nd level distance code */
_
Patches currently in -mm which might be from Joakim.Tjernlund@xxxxxxxxxxxx are
zlib-optimize-inffast-when-copying-direct-from-output.patch
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