On 5/28/07, Nitin Gupta <[email protected]> wrote:
Hi,
This is kernel port of LZO1X-1 compressor and LZO1X decompressor (safe
version only).
* Changes since 'take 5' (Full Changelog after this):
- Added compressor and decomrpesssor as separate and hidden config
options (default: n)
- Cleanups: removed LZO_CHECK_MPOS_NON_DET macro
- removed PTR* macros.
* Benchmarks: (system: P4 3GHz, 1G RAM)
(Using tester program from Daniel)
Following compares this kernel port ('take 6') vs original miniLZO code:
'TinyLZO' refers to this kernel port.
10000 run averages:
'Tiny LZO':
Combined: 61.2223 usec
Compression: 41.8412 usec
Decompression: 19.3811 usec
'miniLZO':
Combined: 66.0444 usec
Compression: 46.6323 usec
Decompression: 19.4121 usec
Result:
Overall: TinyLZO is 7.3% faster
Compressor: TinyLZO is 10.2% faster
Decompressor: TinyLZO is 0.15% faster
TODO: test 'take 6' port on archs other than x86(_32)
* Changelog vs. original LZO:
1) Used standard/kernel defined data types: (this eliminated _huge_
#ifdef chunks)
lzo_bytep -> unsigned char *
lzo_uint -> size_t
lzo_xint -> size_t
lzo_uint32p -> u32 *
lzo_uintptr_t -> unsigned long
2) Removed everything #ifdef'ed under COPY_DICT (this is not set for
LZO1X, so removed corres. parts).
3) Removed code #ifdef'ed for LZO1Y, LZO1Z, other variants.
4) Reformatted the code to match general kernel style.
5) The only code change: (as suggested by Andrey)
-#if defined(__LITTLE_ENDIAN)
- m_pos = op - 1;
- m_pos -= (*(const unsigned short *)ip) >> 2;
-#else
- m_pos = op - 1;
- m_pos -= (ip[0] >> 2) + (ip[1] << 6);
-#endif
+ m_pos = op - 1 - (cpu_to_le16(*(const u16 *)ip) >> 2);
(Andrey suggested le16_to_cpu for above but I think it should be cpu_to_le16).
*** Need testing on big endian machine ***
Similarly:
-#if defined(__LITTLE_ENDIAN)
- m_pos -= (*(const unsigned short *)ip) >> 2;
-#else
- m_pos -= (ip[0] >> 2) + (ip[1] << 6);
-#endif
+ m_pos -= cpu_to_le16(*(const u16 *)ip) >> 2;
6) Get rid of LZO_CHECK_MPOS_NON_DET macro and PTR* macros.
I think it's now ready for mainline inclusion.
include/linux/lzo1x.h | 66 +++++++++++
lib/Kconfig | 6 +
lib/Makefile | 2 +
lib/lzo1x/Makefile | 2 +
lib/lzo1x/lzo1x_compress.c | 259
tested this on ppc and its still good
is there any reason to bother with a test on amd64?
if there is I might be able to get to it tonight
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