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authorJim Keniston <jkenisto@linux.vnet.ibm.com>2011-03-22 16:35:12 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2011-03-22 17:44:17 -0700
commit565d76cb7d5fd7cb010fd690602280a69ab116ef (patch)
treebeff4279da00976e10145820c22e699192056973 /lib/zlib_deflate
parentb12d12596992f608f5506a8dabe4d1299594bd1e (diff)
downloadlinux-565d76cb7d5fd7cb010fd690602280a69ab116ef.tar.gz
zlib: slim down zlib_deflate() workspace when possible
Instead of always creating a huge (268K) deflate_workspace with the maximum compression parameters (windowBits=15, memLevel=8), allow the caller to obtain a smaller workspace by specifying smaller parameter values. For example, when capturing oops and panic reports to a medium with limited capacity, such as NVRAM, compression may be the only way to capture the whole report. In this case, a small workspace (24K works fine) is a win, whether you allocate the workspace when you need it (i.e., during an oops or panic) or at boot time. I've verified that this patch works with all accepted values of windowBits (positive and negative), memLevel, and compression level. Signed-off-by: Jim Keniston <jkenisto@us.ibm.com> Cc: Herbert Xu <herbert@gondor.apana.org.au> Cc: David Miller <davem@davemloft.net> Cc: Chris Mason <chris.mason@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'lib/zlib_deflate')
-rw-r--r--lib/zlib_deflate/deflate.c31
-rw-r--r--lib/zlib_deflate/defutil.h17
2 files changed, 42 insertions, 6 deletions
diff --git a/lib/zlib_deflate/deflate.c b/lib/zlib_deflate/deflate.c
index 46a31e5f49c..d63381e8e33 100644
--- a/lib/zlib_deflate/deflate.c
+++ b/lib/zlib_deflate/deflate.c
@@ -176,6 +176,7 @@ int zlib_deflateInit2(
deflate_state *s;
int noheader = 0;
deflate_workspace *mem;
+ char *next;
ush *overlay;
/* We overlay pending_buf and d_buf+l_buf. This works since the average
@@ -199,6 +200,21 @@ int zlib_deflateInit2(
strategy < 0 || strategy > Z_HUFFMAN_ONLY) {
return Z_STREAM_ERROR;
}
+
+ /*
+ * Direct the workspace's pointers to the chunks that were allocated
+ * along with the deflate_workspace struct.
+ */
+ next = (char *) mem;
+ next += sizeof(*mem);
+ mem->window_memory = (Byte *) next;
+ next += zlib_deflate_window_memsize(windowBits);
+ mem->prev_memory = (Pos *) next;
+ next += zlib_deflate_prev_memsize(windowBits);
+ mem->head_memory = (Pos *) next;
+ next += zlib_deflate_head_memsize(memLevel);
+ mem->overlay_memory = next;
+
s = (deflate_state *) &(mem->deflate_memory);
strm->state = (struct internal_state *)s;
s->strm = strm;
@@ -1247,7 +1263,18 @@ static block_state deflate_slow(
return flush == Z_FINISH ? finish_done : block_done;
}
-int zlib_deflate_workspacesize(void)
+int zlib_deflate_workspacesize(int windowBits, int memLevel)
{
- return sizeof(deflate_workspace);
+ if (windowBits < 0) /* undocumented feature: suppress zlib header */
+ windowBits = -windowBits;
+
+ /* Since the return value is typically passed to vmalloc() unchecked... */
+ BUG_ON(memLevel < 1 || memLevel > MAX_MEM_LEVEL || windowBits < 9 ||
+ windowBits > 15);
+
+ return sizeof(deflate_workspace)
+ + zlib_deflate_window_memsize(windowBits)
+ + zlib_deflate_prev_memsize(windowBits)
+ + zlib_deflate_head_memsize(memLevel)
+ + zlib_deflate_overlay_memsize(memLevel);
}
diff --git a/lib/zlib_deflate/defutil.h b/lib/zlib_deflate/defutil.h
index 6b15a909ca3..b640b6402e9 100644
--- a/lib/zlib_deflate/defutil.h
+++ b/lib/zlib_deflate/defutil.h
@@ -241,12 +241,21 @@ typedef struct deflate_state {
typedef struct deflate_workspace {
/* State memory for the deflator */
deflate_state deflate_memory;
- Byte window_memory[2 * (1 << MAX_WBITS)];
- Pos prev_memory[1 << MAX_WBITS];
- Pos head_memory[1 << (MAX_MEM_LEVEL + 7)];
- char overlay_memory[(1 << (MAX_MEM_LEVEL + 6)) * (sizeof(ush)+2)];
+ Byte *window_memory;
+ Pos *prev_memory;
+ Pos *head_memory;
+ char *overlay_memory;
} deflate_workspace;
+#define zlib_deflate_window_memsize(windowBits) \
+ (2 * (1 << (windowBits)) * sizeof(Byte))
+#define zlib_deflate_prev_memsize(windowBits) \
+ ((1 << (windowBits)) * sizeof(Pos))
+#define zlib_deflate_head_memsize(memLevel) \
+ ((1 << ((memLevel)+7)) * sizeof(Pos))
+#define zlib_deflate_overlay_memsize(memLevel) \
+ ((1 << ((memLevel)+6)) * (sizeof(ush)+2))
+
/* Output a byte on the stream.
* IN assertion: there is enough room in pending_buf.
*/