Attachment 306127 Details for Bug 446085 – Upstream version of the proposed patch

[patch] Upstream version of the proposed patch

446085.upstream.patch (text/plain), 4.34 KB, created by Robert Peterson on 2008-05-20 14:27:55 UTC

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Creator: Robert Peterson

Created: 2008-05-20 14:27:55 UTC

Size: 4.34 KB

patch

obsolete

> gfs-kernel/src/gfs/bits.c |   85 +++++++++++++++++++++++++++++++-------------
> gfs-kernel/src/gfs/bits.h |    3 +-
> gfs-kernel/src/gfs/rgrp.c |    3 +-
> 3 files changed, 62 insertions(+), 29 deletions(-)
>
>diff --git a/gfs-kernel/src/gfs/bits.c b/gfs-kernel/src/gfs/bits.c
>index da08a23..55427bb 100644
>--- a/gfs-kernel/src/gfs/bits.c
>+++ b/gfs-kernel/src/gfs/bits.c
>@@ -31,6 +31,16 @@
> #include "gfs.h"
> #include "bits.h"
> 
>+#if BITS_PER_LONG == 32
>+#define LBITMASK   (0x55555555UL)
>+#define LBITSKIP55 (0x55555555UL)
>+#define LBITSKIP00 (0x00000000UL)
>+#else
>+#define LBITMASK   (0x5555555555555555UL)
>+#define LBITSKIP55 (0x5555555555555555UL)
>+#define LBITSKIP00 (0x0000000000000000UL)
>+#endif
>+
> static const char valid_change[16] = {
> 	        /* current */
> 	/* n */ 0, 1, 1, 1,
>@@ -115,41 +125,66 @@ gfs_testbit(struct gfs_rgrpd *rgd,
>  */
> 
> uint32_t
>-gfs_bitfit(struct gfs_rgrpd *rgd,
>-	   unsigned char *buffer, unsigned int buflen,
>+gfs_bitfit(unsigned char *buffer, unsigned int buflen,
> 	   uint32_t goal, unsigned char old_state)
> {
>-	unsigned char *byte, *end, alloc;
>-	uint32_t blk = goal;
>-	unsigned int bit;
>-
>-	byte = buffer + (goal / GFS_NBBY);
>-	bit = (goal % GFS_NBBY) * GFS_BIT_SIZE;
>-	end = buffer + buflen;
>-	alloc = (old_state & 1) ? 0 : 0x55;
>-
>+	const u8 *byte, *start, *end;
>+	int bit, startbit;
>+	u32 g1, g2, misaligned;
>+	unsigned long *plong;
>+	unsigned long lskipval;
>+
>+	lskipval = (old_state & GFS_BLKST_USED) ? LBITSKIP00 : LBITSKIP55;
>+	g1 = (goal / GFS_NBBY);
>+	start = buffer + g1;
>+	byte = start;
>+        end = buffer + buflen;
>+	g2 = ALIGN(g1, sizeof(unsigned long));
>+	plong = (unsigned long *)(buffer + g2);
>+	startbit = bit = (goal % GFS_NBBY) * GFS_BIT_SIZE;
>+	misaligned = g2 - g1;
>+	if (!misaligned)
>+		goto ulong_aligned;
>+/* parse the bitmap a byte at a time */
>+misaligned:
> 	while (byte < end) {
>-		if ((*byte & 0x55) == alloc) {
>-			blk += (8 - bit) >> 1;
>-
>-			bit = 0;
>-			byte++;
>-
>-			continue;
>+		if (((*byte >> bit) & GFS_BIT_MASK) == old_state) {
>+			return goal +
>+				(((byte - start) * GFS_NBBY) +
>+				 ((bit - startbit) >> 1));
> 		}
>-
>-		if (((*byte >> bit) & GFS_BIT_MASK) == old_state)
>-			return blk;
>-
> 		bit += GFS_BIT_SIZE;
>-		if (bit >= 8) {
>+		if (bit >= GFS_NBBY * GFS_BIT_SIZE) {
> 			bit = 0;
> 			byte++;
>+			misaligned--;
>+			if (!misaligned) {
>+				plong = (unsigned long *)byte;
>+				goto ulong_aligned;
>+			}
> 		}
>-
>-		blk++;
> 	}
>+	return BFITNOENT;
> 
>+/* parse the bitmap a unsigned long at a time */
>+ulong_aligned:
>+	/* Stop at "end - 1" or else prefetch can go past the end and segfault.
>+	   We could "if" it but we'd lose some of the performance gained.
>+	   This way will only slow down searching the very last 4/8 bytes
>+	   depending on architecture.  I've experimented with several ways
>+	   of writing this section such as using an else before the goto
>+	   but this one seems to be the fastest. */
>+	while ((unsigned char *)plong < end - 1) {
>+		prefetch(plong + 1);
>+		if (((*plong) & LBITMASK) != lskipval)
>+			break;
>+		plong++;
>+	}
>+	if ((unsigned char *)plong < end) {
>+		byte = (const u8 *)plong;
>+		misaligned += sizeof(unsigned long) - 1;
>+		goto misaligned;
>+	}
> 	return BFITNOENT;
> }
> 
>diff --git a/gfs-kernel/src/gfs/bits.h b/gfs-kernel/src/gfs/bits.h
>index ed38102..9990bae 100644
>--- a/gfs-kernel/src/gfs/bits.h
>+++ b/gfs-kernel/src/gfs/bits.h
>@@ -22,8 +22,7 @@ void gfs_setbit(struct gfs_rgrpd *rgd,
> unsigned char gfs_testbit(struct gfs_rgrpd *rgd,
> 			  unsigned char *buffer, unsigned int buflen,
> 			  uint32_t block);
>-uint32_t gfs_bitfit(struct gfs_rgrpd *rgd,
>-		    unsigned char *buffer, unsigned int buflen,
>+uint32_t gfs_bitfit(unsigned char *buffer, unsigned int buflen,
> 		    uint32_t goal, unsigned char old_state);
> uint32_t gfs_bitcount(struct gfs_rgrpd *rgd,
> 		      unsigned char *buffer, unsigned int buflen,
>diff --git a/gfs-kernel/src/gfs/rgrp.c b/gfs-kernel/src/gfs/rgrp.c
>index dd7fdcb..f0a4e3f 100644
>--- a/gfs-kernel/src/gfs/rgrp.c
>+++ b/gfs-kernel/src/gfs/rgrp.c
>@@ -1444,8 +1444,7 @@ blkalloc_internal(struct gfs_rgrpd *rgd,
> 	   allocatable block anywhere else, we want to be able wrap around and
> 	   search in the first part of our first-searched bit block.  */
> 	for (x = 0; x <= length; x++) {
>-		blk = gfs_bitfit(rgd,
>-				 rgd->rd_bh[buf]->b_data + bits->bi_offset,
>+		blk = gfs_bitfit(rgd->rd_bh[buf]->b_data + bits->bi_offset,
> 				 bits->bi_len, goal, old_state);
> 		if (blk != BFITNOENT)
> 			break;

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Attachments on bug 446085: 306122 | 306123 | 306127