+ zlib-optimize-inffast-when-copying-direct-from-output.patch added to -mm tree

* + zlib-optimize-inffast-when-copying-direct-from-output.patch added to -mm tree
@ 2009-11-11  0:43 akpm
  0 siblings, 0 replies; 2+ messages in thread
From: akpm @ 2009-11-11  0:43 UTC (permalink / raw)
  To: mm-commits; +Cc: Joakim.Tjernlund, alain, dwmw2, hpa, rpurdie


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@transmode.se>

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@transmode.se>
Cc: Alain Knaff <alain@knaff.lu>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Richard Purdie <rpurdie@rpsys.net>
Cc: David Woodhouse <dwmw2@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---


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@transmode.se are

zlib-optimize-inffast-when-copying-direct-from-output.patch


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